Experiments show dramatic increase in solar cell output

Method for collecting two electrons from each photon could break through theoretical solar-cell efficiency limit

Massachusetts Institute of Technology

CAMBRIDGE, MA — In any conventional silicon-based solar cell, there is an absolute limit on overall efficiency, based partly on the fact that each photon of light can only knock loose a single electron, even if that photon carried twice the energy needed to do so. But now, researchers have demonstrated a method for getting high-energy photons striking silicon to kick out two electrons instead of one, opening the door for a new kind of solar cell with greater efficiency than was thought possible.

While conventional silicon cells have an absolute theoretical maximum efficiency of about 29.1 percent conversion of solar energy, the new approach, developed over the last several years by researchers at MIT and elsewhere, could bust through that limit, potentially adding several percentage points to that maximum output. The results are described today in the journal Nature, in a paper by graduate student Markus Einzinger, professor of chemistry Moungi Bawendi, professor of electrical engineering and computer science Marc Baldo, and eight others at MIT and at Princeton University.

The basic concept behind this new technology has been known for decades, and the first demonstration that the principle could work was carried out by some members of this team six years ago. But actually translating the method into a full, operational silicon solar cell took years of hard work, Baldo says.

That initial demonstration “was a good test platform” to show that the idea could work, explains Daniel Congreve PhD ’15, an alumnus now at the Rowland Institute at Harvard, who was the lead author in that prior report and is a co-author of the new paper. Now, with the new results, “we’ve done what we set out to do” in that project, he says.

The original study demonstrated the production of two electrons from one photon, but it did so in an organic photovoltaic cell, which is less efficient than a silicon solar cell. It turned out that transferring the two electrons from a top collecting layer made of tetracene into the silicon cell “was not straightforward,” Baldo says. Troy Van Voorhis, a professor of chemistry at MIT who was part of that original team, points out that the concept was first proposed back in the 1970s, and says wryly that turning that idea into a practical device “only took 40 years.”

The key to splitting the energy of one photon into two electrons lies in a class of materials that possess “excited states” called excitons, Baldo says: In these excitonic materials, “these packets of energy propagate around like the electrons in a circuit,” but with quite different properties than electrons. “You can use them to change energy — you can cut them in half, you can combine them.” In this case, they were going through a process called singlet exciton fission, which is how the light’s energy gets split into two separate, independently moving packets of energy. The material first absorbs a photon, forming an exciton that rapidly undergoes fission into two excited states, each with half the energy of the original state.

But the tricky part was then coupling that energy over into the silicon, a material that is not excitonic. This coupling had never been accomplished before.

As an intermediate step, the team tried coupling the energy from the excitonic layer into a material called quantum dots. “They’re still excitonic, but they’re inorganic,” Baldo says. “That worked; it worked like a charm,” he says. By understanding the mechanism taking place in that material, he says, “we had no reason to think that silicon wouldn’t work.”

What that work showed, Van Voorhis says, is that the key to these energy transfers lies in the very surface of the material, not in its bulk. “So it was clear that the surface chemistry on silicon was going to be important. That was what was going to determine what kinds of surface states there were.” That focus on the surface chemistry may have been what allowed this team to succeed where others had not, he suggests.

The key was in a thin intermediate layer. “It turns out this tiny, tiny strip of material at the interface between these two systems [the silicon solar cell and the tetracene layer with its excitonic properties] ended up defining everything. It’s why other researchers couldn’t get this process to work, and why we finally did.” It was Einzinger “who finally cracked that nut,” he says, by using a layer of a material called hafnium oxynitride.

The layer is only a few atoms thick, or just 8 angstroms (ten-billionths of a meter), but it acted as a “nice bridge” for the excited states, Baldo says. That finally made it possible for the single high-energy photons to trigger the release of two electrons inside the silicon cell. That produces a doubling of the amount of energy produced by a given amount of sunlight in the blue and green part of the spectrum. Overall, that could produce an increase in the power produced by the solar cell — from a theoretical maximum of 29.1 percent, up to a maximum of about 35 percent.

Actual silicon cells are not yet at their maximum, and neither is the new material, so more development needs to be done, but the crucial step of coupling the two materials efficiently has now been proven. “We still need to optimize the silicon cells for this process,” Baldo says. For one thing, with the new system those cells can be thinner than current versions. Work also needs to be done on stabilizing the materials for durability. Overall, commercial applications are probably still a few years off, the team says.

Other approaches to improving the efficiency of solar cells tend to involve adding another kind of cell, such as a perovskite layer, over the silicon. Baldo says “they’re building one cell on top of another. Fundamentally, we’re making one cell — we’re kind of turbocharging the silicon cell. We’re adding more current into the silicon, as opposed to making two cells.”

The researchers have measured one special property of hafnium oxynitride that helps it transfer the excitonic energy. “We know that hafnium oxynitride generates additional charge at the interface, which reduces losses by a process called electric field passivation. If we can establish better control over this phenomenon, efficiencies may climb even higher.” Einzinger says. So far, no other material they’ve tested can match its properties.


The research was supported as part of the MIT Center for Excitonics, funded by the U.S. Department of Energy.

From EurekAlert!

183 thoughts on “Experiments show dramatic increase in solar cell output

  1. “could bust through that limit, potentially adding several percentage points to that maximum
    output. ” Such an insignificant increase doesn’t even rate a mention in the media.

      • The increase is a whopping 100% of the increase!
        Rose is a rose is a rose is a rose!
        Pigeons in the grass, alas!

    • Why the dismissive tone in many of these comments? This work is part of the incremental scientific process and we should celebrate the potential of the achievement. It may not pan out, may never be commercially viable, may be something that isn’t available for years and it certainly doesn’t justify the current subsidies for solar being supplied to the grid. But it is an interesting approach and is worth being reported here.

        • …And the problem is that the source of solar energy lacks sufficient density to offer any real practicality as a supplier of the world’s present needs, just as desperately as does the wind, so the technology cannot produce a “silk purse from a sow’s ear”. It really is futile for anything except small loads in “off grid” locations until battery technology achieves a quantum breakthrough which enables us to store 10x the power within the present size/weight parameters.

      • The tone is dismissive mostly because most of us have a disdain for this style of “science via press release”, it’s been used too many times in the past to sell questionable results.

      • Hafnium is a rare metal byproduct of zirconium production. Prices of high analysis Hf is ~$1500 – $2000/kg. The high price may not be the the most serious problem. It’s byproduct nature with Zirconium means a huge demand for the tiny percentage of Hf in Zr. I would also have tried yttrium and the lanthanides (rare earths). They are much more abundant than Hf and the cheaper ones (La and Ce under $100/kg).

        The surface chemistry is apparently important and the valency of Hf is 4. The Rare earths are 3, but Cerium has an oxidation state of 4 also.

        • Gold Price is ~ $45,000/kg and gold has constituted the metalization in certain semiconductors (GaAs FETs and GaAs MIMICs for example) for quite awhile now …

      • “This work is part of the incremental scientific process and we should celebrate the potential of the achievement.”

        I do not think that anyone has any problem with progress. The problem is the use of minor incremental advances to justify capital-destroying policies on the part of regulators.

    • As an ex-satellite systems engineer, I find this extremely exciting. We drove and bought the most efficient cells available, as it lengthened lifetime and reduced weight. It’s not just the weight of the cells themselves, but the structures used to unfurl and dampen panel oscillations.

      As a retired engineer, I find it interesting because I live way too far away for the electric company to reach me without paying half a million dollars to get power to the property. I have to use solar with battery storage – and a generator for the few occasions during the winter when the sun just doesn’t come through the clouds for weeks at a time. This might generate some power in reduced light, but definitely help during the shorter daylight hours in winter.

      IF it really works. Boeing and Lockheed can afford to pay those prices. I’ll be dead before they are cheap enough for Earth-bound generation.

      • I find that fascinating that you are off-grid because of the expense of the hook-up. Do you own a huge tract of land? Are you in an inaccessible location? What is it that keeps you from a normal grid connection?

        • Imagine 1-2 large bucket truck(s), a large auger (drilling) truck, a 4-5 man union linemen crew and one union lineman foreman for an above ground sub-transmission/distribution electrical line installation, no matter how small the job. You will need a high-capacity switch to connect to the existing line, maybe the more expensive automatic re-closing design, depending on your local utility’s requirements. Wood poles, cross-arms, aluminum conductors, insulators, a service transformer, and other various expensive hardware will be needed. Why don’t we add in a little engineering design, land survey and costly right-of-way acquisition while we’re at it. You might save some money by “direct-bury” of the underground electrical cables, with an integrated flexible conduit, using a specialized tractor-type piece of equipment if terrain, foliage and soils allow.

          See where we are going here, Pop?

          This little example of real-world electrical system installation should serve as a precautionary tale for those AOC-types that think everything is easy.

          • “a precautionary tale for those AOC-types that think everything is easy” I’ve always said; The less you know about something, the easier it seems to do.

      • K-Kook,
        I’m a current satellite systems and power engineer. We buy our solar cells from a company that has a host of triple-junction and 4-junction cells that are already over the supposed/reported 29.1% theoretical limit (ranging from 29.5% to 32% depending on what orbit you are going to). Yes these are expensive and prohibitive for earth-based applications, but the 29.1% theoretical limit is incorrect. A science writer who presents incorrect facts–say it ain’t so {sarc}!!!

  2. “….While conventional silicon cells have an absolute theoretical maximum efficiency of about 29.1 percent conversion of solar energy, the new approach, developed over the last several years by researchers at MIT and elsewhere, could bust through that limit, potentially adding several percentage points to that maximum output….”

    So…we’re talking about moving from a theoretical maximum of 29.1% up to a theoretical maximum of , perhaps, 34%?

    And how much did that cost us?

    • “And how much did that cost us?”

      Probably a lot less than the costs involved in creating the latest “must have” gadget that you are all expected to buy to replace the previous “must have” that is only a couple of years old and still in perfect working order but is now slower due to the latest software update.

      • Two wrongs do not make a right. Showing that the human race does one stupid thing does not excuse us doing another.

        • Big difference is the fact that if the research is successful and a more efficient solar panel is developed and goes into mass production. This would result in greater electricity generation per square metre than today, such a move would be beneficial.
          Unlike the production of a newer model gadget that simply condemns the previous device to landfill, a process that is repeated time and time again.

          • “such a move would be beneficial”

            Not to me. Won’t do a dang thing for me.

            Whereas my Samsung smarty phone does a lot.

          • And it will make the sun shine 24/7, right Phil? Or does it come with built-in batteries?

            It is highly unlikely that they can even match conventional PV cost per kW-hr, but the propaganda machine has a new talking point about solar power just got twice as efficient, dishonestly implying half the cost.

            I’m calling EurekAlert! on this BS.

          • You leave out the new device does a lot, it produces huge economic demand and jobs unlike the solar panel.

            lets compare the size of what you are talking about
            Mobile phone sales market …. $522 billion in 2018
            Solar Panel sales market …. $32 billion in 2018

            The entire renewable energy market is only estimated at $1500 billion which isn’t even in the same playing field as the total communication market. The US communication sector alone is near $1000 billion.

          • It would only be beneficial if it means that the cost of solar energy goes down.
            That’s why cost matters.

          • “Phil July 7, 2019 at 5:09 am
            Big difference is the fact that if the research is successful and a more efficient solar panel is developed and goes into mass production. This would result in greater electricity generation per square metre than today, such a move would be beneficial.
            Unlike the production of a newer model gadget that simply condemns the previous device to landfill, a process that is repeated time and time again.”

            Bafflegab insinuations that ignore reality.
            Replacing less efficient solar cells accomplishes your claim of >”condemns the previous device to landfill”

            “result in greater electricity generation per square metre than today”; The proper response to specious claims like this one is ‘Big Whup”.
            Your claim is an attempt to distract from the fact; solar farms and solar arrays are inefficient energy collection mechanisms forcing humans to trade massive acreage for small energy return.
            Where LNG, coal or nuclear facilities produce much greater energy returns for miniscule land usage.
            This is before solar cell uses are subsidized and operate under political price support mechanisms.

          • –Gamecock July 7, 2019 at 6:14 am
            “such a move would be beneficial”

            Not to me. Won’t do a dang thing for me.

            Whereas my Samsung smarty phone does a lot.*–

            It could make different solar energy in regards to satellites in space.
            Satellites in space use solar panels because that is viable way to get electrical power.
            They basically get constant sunlight and need very little in terms battery power.
            And your smart phone or the internet, does not work without the satellites

          • gbaikie July 7, 2019 at 2:24 pm
            re: “And your smart phone or the internet, does not work without the satellites

            What support do satellites provide? – I want to check if you really have any idea at all OR are simply repeating what you’ve heard from elsewhere …

        • Equally showing that the human race does one stupid thing does not mean everything it does is stupid.

          Science is about pushing boundaries. This pushes a very important boundary. The possibility of increasing solar cell efficiency by ~17% with possible further increases has potential in a lot of areas.

          I’d rather see taxpayers’ money spent on this than on funding Mann and others to sit on their backsides and pontificate!

          • Most important benefit is where space and weight are premium. Obvious use is space tech, however, lots of your toys and must have gadgets could be powered by sun or ambient light. Think of not needing a wall wart and outlet. Better solar power on all those satellites means your toys work better. We live off the grid on a sailboat. We use all solar flashlights on our boat. No batteries to buy or discard. This means also the packaging waste stream is gone. Waste is a huge problem in the Caribbean and in many places remote from adequate handling. We have 660 watts of 18% efficient solar for our batteries. Double that in a couple years and I won’t run the generator again. That means not dealing with diesel and fuel docks. It was only a few years ago that 6% was the best you could get. I am all for subsidized research but strongly opposed to subsidizing the retail products.

          • @Cube: Yours is the wrong calculation. The right calculation (which you might remember from grade school) for %improvement is (New – Old)/Old. In this case, (35-29)/29 ~= 21% (actually better than Newminster’s #, which I think was (New – Old)/ New–the negative of that would be the percentage decrease from the New back to the Old). What you calculated was the percentage points improvement. While percentage points can be relevant in certain contexts, if we’re talking the increase in efficiency, the (N-O)/O is the relevant formula.

        • It is actually a fairly significant amount. You are poopooing a 20% increase in output and efficiency?

          • That’s a **THEORETICAL** 20% increase. It’s not a bad thing, but let’s don’t count our electrons before they hatch (or whatever verb applies to electron generation). FWIW, current solar cells typically yield about 15-20% efficiency, not the theoretical 29%. There’s probably a bit of development work to be done before this becomes significant. If it ever does.

          • If it means the cost of the cells go up by more than 20%, then yes, we are poopooing it.

        • And where in that article do you get the idea that someone did something stupid? I guess you want to end all research.

          I think there’s someone stupid here, but it’s not the researchers.

          • Nope. We are a bunch of science nuts (and quite a few actual scientists) who don’t believe everything we’re told. Until other scientists can reproduce the results it is little more than an hypothesis. But that doesn’t mean we don’t care. We are just skeptical, as all scientists should be.

    • well it was given as 35% not 34, so that is a 6% increase over 29% in efficiency. That’s over 20% improvement. Well worth having. If you could increase the efficiency of any other system by that much it would be BIG news anywhere.

      “And how much did that cost us?”

      The cost of the research will be immeasurably small compared to what has been thrown at solar so far. If you are out to criticise something, then at least think long enough to make a valid remark.

      I don’t see solar PV as means to save the planet but as a means of going off grid and not having to depend on central govt. controlled distribution and industrial scale plant, it seems like a very valuable option to have.

      • If it ever gets to the point that solar can replace central government controlled distribution, it will be banned or taxed to unaffordability.

      • The main point; Solar will never be of use except for off grid power. Wind turbines will never be of any use..

        • Nonsense. My step-daughter’s electric bill last year was negative $200, because of the solar panels on her roof. Sure they don’t work at night, but it means she puts more back into the grid in the daytime than she takes at night.

          BTW, one place to put solar panels with virtually no downside is parking lots. Shaded cars in the summer, so when you come out they’re not steaming hot; and keeps rain snow off (assuming they’re provided with gutters). Wouldn’t mind them on my driveway, either; less snow to shovel in the winter.

          • You do realize solar panels don’t work with snow on them, right? Oh, btw, you do know your daughters neighbors subsidized her “-200 dollar” power bill, don’t you?

          • It depends on what you mean by “work.” If there is an inch or two of snow on them, a lot of light goes right through the snow and produces power. Not rated power, but some.

          • @Leghorn: She should be so lucky to get snow. (She lives in Phoenix, where they’ve gotten measurable snow seven times in recorded history, only once over 1/2 inch.)

            And where I live (Maryland), it does snow, but the roofs are steep enough that the snow doesn’t stay for long on roofs, much less slippery solar panels (I’ve seen it come off neighbors’ solar panels). In general, if you get significant snow, the roofs are fairly steep.

            And btw, once the solar panels lose their snow, if there’s still snow on the ground, it apparently enhances the output of the panels, because the snow reflects light. (Which is why you can get sunburned skiing.)

      • “If you could increase the efficiency of any other system by that much it would be BIG news anywhere.”

        We’re not talking about any other system.

        • Every system out there can be made more efficient. That’s a given. It doesn’t matter what system you are talking about.
          What matters is how much does that extra efficiency cost.
          In the real world you have to make decisions regarding cost vs. benefit.
          This article tells us the theoretical benefits, there is no mention of cost.

      • It doesn’t matter how much money has been wasted on solar in the past.
        What matters is how much does it cost to manufacture a cell in the here and now. If the increase in cost is greater than the increase in output, then this development while interesting is an economic loser. It would be great news for NASA, but it would be a big nothing burger for the rest of us.

        • This is a Science site, not a global warming denialist site. As such, one should maintain an open mind.
          There are many, many places that a 20 mile extension cord is trumped by a solar panel and batteries all the time.
          Please be a little more reasonable. Being dogmatic should be left to Alarmist sites.

          • Speaking of needing a life, George you should see if a friend will lend you theirs.
            There are many places? Name them. What percentage of total power generation are you talking about.
            This site is about many things, science, economics, politics, you name it.
            The question in front of us is both science and economics, heavily polluted by politics.

            If the cell touted here is 20% more efficient, but twice as expensive, then just about everyone of those places that are off the grid, are going to stay with the existing cells.

            Only places with limited space or where weight is absolutely critical will pay more for the same amount of power.

            That’s economics, something you should spend some time studying.

      • If solar panels could be made 90% efficient they would become really useful. At that level, most of the supporting fossil fuel generators and nuclear plants would only need to run just hard enough to support a sudden grid breakdown. That efficiency would also greatly reduce the amount of space an materials demanded.

        Of course, nothing will really solve the intermittency problem of solar and wind power. They are at best a minor stopgap for transition to nuclear power for electricity.

        The next big breakthrough will be CO2-> Hydrocarbon conversion, powered by nuclear power. It should be clear now to all that any kind of electric distribution system for really widespread use(transportation, aircraft) is extremely difficult and inefficient. There is no method even on the horizon that matches hydrocarbons for energy density, portability, cost, and safety. Making them from CO2 will at some point make economic sense.

        • The cost of concentrating and purifying a very diffuse gas from its very low concentration up to the purity needed to convert it back to a hydrocarbon and oxygen is prohibitive. Besides, we already have some highly efficient natural processes for this. From phytoplankton to trees, we can use any plant to do this job for us, and most of them will do it for free. In about 100 years, when we get most of our energy from fission (fusion will still be just around the corner) we will mine coal for the hydrocarbons to provided the feedstock for all our petrochemicals. We will recycle more plastic because it will pay to do so.

      • The objection is not the cost of the research. The objection is the potential cost of the manufacturing.

        If these new solar cells are 20% more effective but cost 40% more to produce, they’re not much of a win, are they? However, they haven’t discussed manufacturing costs, so we just don’t know.

        It will undoubtedly be a boon for the one place where solar panels are massively effective: providing power for cruising sailboats.

      • Greg,
        If you could increase the fuel efficiency of your $25,000 car by 20%, but the car will now cost $250,000 and have the same useful life as before, would that be “well worth having”? What if it costs $2.5 million and has a three year useful life?

        There is no hint about how much the new hybrid cell might be expected to cost, or whether it can be expected to last as long as conventional cells. Obviously a 20% efficiency improvement at less than 120% of the cost is worth having (assuming that you think that unreliable energy is worth having in the first place). There would also be niche applications where there is a strictly limited space available, and no option to just connect to the grid, so that some consumers would think it worthwhile to pay a premium for the kW capacity. But for the vast majority of applications, this would only be relevant if it makes solar power (implemented as a 24/7 dispatchable system with batteries or other storage) cheaper than natural gas, taking into account all of the system costs, cradle-to-grave.

      • We have astonishingly few weather stations, considering. We could do with a *lot* of cheap automatic stations periodically transmitting their records. Even if not up to the standard of well sited properly installed “real” weather stations, it would be nice to fill in some of that white space on the map. Solar cells plus batteries are just the ticket for powering the automatic stations we can make these days, and intermittent data is better than *no* data. This level of improvement in the PV cells would mean you could charge the batteries more and stay operational more often. The report is very clear that this technique is not yet commercially ready, but when it is, there ARE real applications waiting for it. Powering cities? No. Powering sensor networks in rural areas? Yes.

        • What’s cheaper, increasing the size of the solar panel on your weather station by 20%, or keeping it the same size and buying these new solar cells instead?
          There is no technical reason for not installing all the weather stations we might need. The issue stopping us is cost, something these new cells probably won’t help with.

    • Didn’t cost you a dime.

      Cost some researchers very little.

      The cost of PV (installed cost, without government subsidies) has plummeted by more than 2/3 in just the last decade.

      • Gee, Duane. Now if only you could make the sun shine at night, you might have something there.

        • Solar may not be a baseline technology – but this improvement should be lauded. Many applications exist where this could help. Remote cell towers could be such an application.

          Not sure why everyone is being so reflexively negative.

          • Because wind and solar are being pushed as a practical alternative for conventional power. Grid electricity is a service, not a commodity, and the degree to which wind or solar can replace thermal or hydro electric capacity is somewhere about bupkis.

          • This improvement is meaningless.

            When the sun shines most solar adopters already have massively more power than can be used.

            But solars capacity factor -the ahh it can produce grid scale power – is less than 19% on an annual basis – varying slightly depending on latitude andlocal weather (clouds) conditions.

            Increasing panel efficiency does zero to address the problem of capacity factor – and the only way to change that is to make the sun shine longer and stop clouds.

          • Mostly I see healthy skepticism over a way too optimistic press release.
            Most of the negativism is being directed towards those who are attempting to over sell this small advance.
            PS: Anyone who declares that costs don’t matter, deserves all the negativism thrown his way.

        • The cost is the cost. Nobody claims that PV works at night. But energy produced and used with PV is energy that does not release air and water pollutants, and does not require the ongoing cost of fuel, and the maintenance cost of PV is drastically less than that of any central mechanical power plant.

          The energy produced by PV can easily be stored too, for use when the sun doesn’t shine. Whether via banks of batteries, or by converting electricity and water to make hydrogen gas.

          Indeed, energy storage has for centuries been the basis of virtually all hydroelectric power. Dams store water in reservoirs, then releases the water to make electrical power as required.

          I don’t recall the luddites who oppose PV going to the mattresses to crusade against hydroelectric reservoirs going back to the late 1900s.

          • “But energy produced and used with PV is energy that does not release air and water pollutants”
            Lot’s of pollutants are released during the manufacture. How do you account for that?

            “maintenance cost of PV is drastically less than that of any central mechanical power plant.”

            You’ve never maintained a large base of solar cells or wind turbines I’m guessing.

            “Whether via banks of batteries, or by converting electricity and water to make hydrogen gas.”

            Banks of batteries require *lots* of maintenance. And exactly who is creating hydrogen gas for use as fuel for electricity generation?

            “Indeed, energy storage has for centuries been the basis of virtually all hydroelectric power. Dams store water in reservoirs, then releases the water to make electrical power as required.”

            Lot’s of inefficiencies in such an operation, especially if the PV generation is used to pump water into the reservoir for later use.

      • So spending tax money doesn’t cost anything. Really?
        As to the claim that the cost of PV’s has been plummeting, I’ve often seen that claimed, but I’ve never seen it proven.

      • Uh, Duane – “… funded by the U.S. Department of Energy.” It cost me a “dime”. And probably a very inefficiently spent dime. TANSTAFL

      • Keep in mind that research done at Universities often is a major first step in a career for a budding Scientist. I can tell you, working on a project with potential future application is much more valuable to the students of a forward-thinking professor than listing to the ramblings of a old timer with no original thoughts.

      • Some of the cost reduction is from dumping by Chinese solar manufacturers. When the Chinese government cut solar installation subsidies, the manufacturers had to get rid of their excess capacity.

    • Not only that, but how rapidly does it degrade and how much does the efficiency drop off as it degrades.

      • Indeed… I recall reading that every electron generated in a solar cell results in permanent degradation of that solar cell, and therefore a solar cell has a finite lifespan dependent on (among other things) the amount of electricity it generates. Unless the more efficient cells are significantly cheaper to manufacture, it seems to me that you are engaging in the robbing of Peter to pay Paul with systems such as the one proposed.

    • “While conventional silicon cells have an absolute theoretical maximum efficiency of about 29.1 percent conversion of solar energy, the new approach, developed over the last several years by researchers at MIT and elsewhere, could bust through that limit, potentially adding several percentage points to that maximum output.”

      Theoretical research under ideal and pristine laboratory conditions.

      “That produces a doubling of the amount of energy produced by a given amount of sunlight in the blue and green part of the spectrum.”

      So,instead of carpeting vast acreage with low power producing solar cells, do they intend to put acres of solar cells above the ozone layer that blocks high energy light frequencies?

      It’s still a theoretical, unproven under real world conditions, claim. Where, even if researchers achieve their maximum results, it is an incremental increase; not a breakthrough.

  3. Yawn. Wake me when this new process can produce solar power that is way cheaper than now.

    • You do realize that the installed cost of solar power (excluding any government subsidies) has decreased in cost by more than 2/3 in the last decade, right? And that any process that leads to a 20% increase in efficiency is going to be much cheaper to buy once the manufacturing learning curve is complete.

      What else you you buy that has dropped in cost by 2/3 over the last decade. Not food, not housing, not consumer goods, not transportation.

      • There are all kinds of goods that have dropped in price and are better today. Take televisions for example, a 55″ screen wasn’t available or affordable that long ago and can now be had for $500 or less. The same is the case for all kinds of consumer electronics. Even automobiles on an inflation basis are more affordable today and are more reliable.

        Fundamentally, miniaturization of electronic processing and memory makes all electronics goods potentially less expensive. What’s a good Terabyte drive cost today vs its cost a decade ago?

      • You can’t fairly compare technology pricing to things like food, housing, and transportation lol.

        And if you are basing the price drop on a per watt basis or something…well, there’s RAM on a per byte basis. PC CPUs on any number of benchmarking bases. 4k TVs within the same size ranges. On and on.

      • The fact that something was egregiously unenvironmentally friendly and uneconomically viable, and now in the latter respect is only very uneconomically viable, is not a success story is it!

        Solar puts up power costs. End of. There are associated costs to the grid, as well as the manufacturing/installation/subsidy costs.

        In the UK the capacity factor is 8%, yes EIGHT PERCENT.

        With a reasonable life assumed, it’s still debatable if solar panels actually provide as much energy as it takes to manufacture them.

        They only exist because of insane distorted energy policies and politics.

      • Puhleeze. The fact that it may have dropped in cost somewhat has nothing to do with how it compares to conventional power, and solar is still way more expensive. Indeed, without government subsidies and “carbon” punishments of fossil fuels, it would not exist as a supply of grid electricity, requiring backup power as it does. It doesn’t come close to competing on a level playing field, and likely never will.

      • I wouldn’t have PV on my house for free. What do you do for the night or an overcast day? Pack a small building w/a battery rack? PVs aren’t much use w/o a connection to a standard utility connection, and if you have that, why bother?

        • “PVs aren’t much use w/o a connection to a standard utility connection, and if you have that, why bother?” This is a trick question, right? Let me see… reduce your electric bill to more or less zero?

          • I have solar PV on my roof because the other electric consumers pay for it in their increased bill.

            CA’s PV mandate for new rooftops is insane. They already have too much industrial-scale PV for the system to handle during low load levels. CA pays other states and Mexico to take the excess. Uncontrollable rooftop PV will exacerbate the problem.

          • mcswell, not an economist, are you. Teachable moment — look up payback period for solar installations supplementing a standard utility connection (with & without subsidies). Consider cost of panels, installation, maintenance, replacements, etc, etc, etc.

            PS –my electric bill avg/month is ~ $60 US a month, more in winter, less in summer. Hardly much of an item to save on.

      • Duane, factual statements like “… installed costs of solar power … decreased in cost by more than 2/3 in the last decade …” require some solid sourcing.

        A solid estimate of the true cost impacts of solar on operating bulk power supply systems would help. Standby reserves, operating reserves, spinning reserves, frequency support, voltage support, etc. provided by conventional generation must be considered. Additional transmission costs from remote solar installations is also a cost concern.

        Watch what happens in California over the next few years. If the surrounding states raise purchased power costs, all hell will break loose. CA cannot rely on the Federal government to keep Pacific Northwest hydropower cheap forever. And coal-fired generation has been a mainstay of CA imports for decades.

      • “And that any process that leads to a 20% increase in efficiency is going to be much cheaper to buy once the manufacturing learning curve is complete.”

        Ummm… no.

        Very broad and sweeping statement there. If you re-read the quoted article they mention the need to product ultra thin layers of material in order to get this process to work. This manufacturing learning curve MAY eventually become complete, or we may get fusion power (remember, just around the corner.)

        It might happen. It also might not. You can’t assume it as a given.

      • Comparing mature products with emerging products is not a valid test.
        But then you already knew that.

        From the description, these cells are more difficult to manufacture than existing cells. That’s going to mean they cost more.

  4. In terms of the science and engineering this is good. However, this will not affect the night time performance of PV systems!

    • Night time performance seems to be mostly irrelevent to the herd, its the virtue signaling that is he primary motivator for the multi-thousand dollar investment.

      In my region, many schools and government buildings have large solar installations on them, almost none of which actually face south toward the Sun. My neighbor has them on the north facing side of his roof so they can be clearly seen by people driving by, I would not be surprised if they’re fake. I love it!

  5. I will never bad mouth hafnium oxynitride again…:)
    One thing to ponder does keeping the 8 angstrom layer clean matter?

    • They are talking about a very thin layer of hafnium between the organic layer and the silicon layer. They describe energy transfer in the device as using excitons. That’s what’s in the press release. Past that, you have to read the original paper.

      It’s not clear to me whether they have constructed an actual photovoltaic cell with dimensions measured in centimeters or just a test cell with dimensions measured in micrometers. In the full size cell, the instrumentation is straightforward. With the tiny test cell, they end up using some kind of proxy to impute the device’s performance. As we all know from climate science, the use of proxies is unreliable.

  6. All theoretically interesting, and it should permit a smaller area of cells for a given output. But for practical purposes the questions are, what do the new cells cost, weigh and what is their life?

    For ground applications cost is much more important than area.

    For space applications weight is much more important than area.

    Life is extreamly important in both applications.

    • All true. If they are light enough, these could be used on auto bodies to enhance EV/hybrid range. Toyota and a company in the Netherlands are working on this.

      • Not just weight, but thickness as well. Making your car half an inch taller will impact the aerodynamics of your car.

  7. Ok so its a small improvement in output, but its still intermittent current flow. One obvious part solution. Make the owners f these solar panels farms , and also the windmills each have battery, at their expense, then we can draw on the steady supply of real energy.

    But no way, they will say that its up to the government to supply the batteries.


  8. It still fails when it’s dark. So, to be blunt, who cares?????

    (We’ve had solar light forever, but that didn’t stop the sale of light bulbs.)

  9. One of the things that puzzles me is the idea of fighting AGW by using solar panels. The primary cited problem in AGW is CO2 capturing energy from the sun and keeping it. How is a solar cell doing anything different? The energy captured by a solar panel will be used to perform work and inefficiencies mean that all work eventually turns into heat. Is their use just illiteracy of the laws of thermodynamics? Solar panel are far more efficient than CO2 so is using them worse than releasing CO2?

  10. First this appears to be the original paper’s catchy title:
    “Sensitization of silicon by singlet exciton fission in tetracene”
    available online: (paid) https://www.nature.com/articles/s41586-019-1339-4
    Free: https://www.researchgate.net/publication/334209900_Sensitization_of_silicon_by_singlet_exciton_fission_in_tetracene

    I’m a listing rusty but …

    To start, an exciton is just a name for an electron hole pair which are held together by attraction. I’m not familiar with exciton materials, but it sounds as if the term is just a way of describing materials with odd energy levels.

    What appears to happen, is that an electron hole pair is created by the absorption of high energy UV light at 2.4ev. This is then rapidly changed into two separate energy states of 1.25ev each. That is nothing new, but the trick has been translating the electron-hole energy of 1.25ev into electric charge. By putting a layer of Hafnium Oxide with an intermediate energy bands (and an SIO2 layer), it seems possible to connect the light sensitive material to that producing charge and current or …. to use an analogy suitable for Anthony — a whitworth screw to a metric nut.

    • When these things die, they should be treated as hazardous waste for disposal as they contain heavy metals, polycyclic aromatic hydrocarbons and who knows what else.

      • “… contains chemicals known to the State of California to cause cancer, birth defects or other reproductive harm.” OMG! };>)

  11. No need to run it down. This is good work. It may be a small gain but who knows where it will lead?

    • re: ” but who knows where it will lead?”

      Maybe as the CPVC (concentrated photo-voltaic cells) in a Hydrino-based Suncell ™ generator?

    • Not sure how you go from a company providing solar cells to the space industry at huge cost to something about the domestic market. These sorts of companies can also grind lenses so orbiting satellites have resolution of 1m but it doesn’t really change the lenses in domestic products much.

      • The article starts with: “Method for collecting two electrons from each photon could break through theoretical solar-cell efficiency limit” and goes on to say that the maximum theoretical efficiency of a conventional cell is 29.1% without mentioning other kinds of cells already beat this. I think the article is misleading in this respect. . That’s my opinion.

    • I haven’t read your article but agree more efficiemt systems are already out there. The reason this is news is that it is an improvement on a silicon substrate which is easy to manufacture. The gallium arsenide types are more efficient but much more expensive to make.

  12. I’ve read about many dramatic improvements in solar panels over the years. Just like dramatic improvements in batteries. Wake me up when this is not in the lab and actually in mass production.

    • Yes that is the problem and dramatic up until now is a few percent which often gets degraded because the new improved version has a sharper decline with age.

    • I was thinking the same thing. I guess this could help the little solar-charged battery lights in people’s yards last alittle longer into the night. Woo-hoo!

  13. re: “The original study demonstrated the production of two electrons from one photon”

    Maybe, just maybe if physicists stopped pussy-footing around with the idea that light is a particle and applied some sound wave theory to the problem they MIGHT make some progress on getting the efficiency up! Demonstrating transverse EM wave propagation is child’s play with polarizers/gratings at radio and light wavelengths, and I’ve yet to see ANY convincing argument that demonstrates a longitudinal ‘particle’ propagation of light theory.

    We have a pretty good grasp on efficient, wide-band antenna design, maybe some MEMS (Microelectromechanical systems) technology is required to fabricate the proper structures to accomplish this for ‘light’ wavelengths …

      • tty July 8, 2019 at 2:49 pm
        Photoelectric effect.

        Science takes a step backward again. Thanks for playing. (You don’t think some of us ALREADY know about the ‘effect’ Einstein received a Nobel prize for 100 years ago? This is the ’cause’ of the rut we are in; a field that needs re-invigorating with new/modified QED theory. Doubt me? Why does Steven Weinberg take stand he does? Link below.)

        “Steven Weinberg on What’s the matter with quantum mechanics?”

  14. How much electricity does the most efficient solar cell produce at midnight?


    How much electricity does the least efficient solar cell produce at midnight?


    The real problem is that sun sets every day. That means you must have two generation systems. One of which will always be idle and producing no energy even though the capital cost continues to accrue.

  15. So they added an extra layer that was only 8 angstroms thick.
    Sounds expensive.
    Also, how durable is it.

    • The cost of an energy source that does not produce useful energy is really irrelavent.
      Electrical energy eqipment which cannot reliably serve demand is really just a toy. It has no real market value.
      A cost of zero is too high.

  16. Rather than a bottoms up perspictive, I prefer a top down analysis.

    I have read somewhere that if solar panels could capture 100% of the sun’s energy that falls on the ground, providing enough power for Singapore would require a solar panel field three times the size of the city.

    That, alone, tells me improvements in efficiency will not result in solar replacing whatever currently powers the grid anywhere. And when you consider battery requirements to get you through the night, and the additional panels needed to keep those batteries charged, then anyone planning on solar making a significant impact on the grid is just tilting at windmills (and that segues us into a discussion on wind turbines).

  17. Energy research is welcomed. Positive results are welcomed more. 20% increase is significant. This is better money spent than all the climate models combined.

    • Not accounting for “manufacturing costs” a 10 micrometer layer would be only about $0.02 worth of Hafnium per square meter.

      Of course my math might be off a little.

  18. It’s a good basic research project, and the engineering is a notably achievement, but is it economical? Sustainable? Does it become economical and sustainable in a frame where we assume… nay, assert, catastrophic anthropogenic global warming?

    • CAGW is always at least 30 years out. Unless you are AOC.

      CliSci alarmists are like Popeye’s Wimpy: Give me your society, economy and energy systems today and I will give you a payback (sometime) in the future.

  19. “The material first absorbs a photon, forming an exciton that rapidly undergoes fission into two excited states, each with half the energy of the original state.”

    “That finally made it possible for the single high-energy photons to trigger the release of two electrons inside the silicon cell. That produces a doubling of the amount of energy produced by a given amount of sunlight in the blue and green part of the spectrum.”

    How does cresting two electrons each with an energy that is half the original state equate to a doubling of the amount of energy produced?

    If I remember my physics and chemistry correctly the voltage output of a process is directly related to the energy level produced. If the electrons being produced have half the energy level then they will produce half the voltage output. It’s why an alkaline battery and a nickel-hydride battery have different output voltages.

    I’ll admit I haven’t read the actual article yet but the abstract certainly leaves a hole big enough to drive a truck through. Power is voltage times current. If you double the potential current but halve the voltage I don’t see how you can get any effective increase in the power available!

    Someone tell me where I have gone astray!

  20. Every kilowatt of power from solar means less reliance on Saudi Arabia, Iraq, Iran, Venezuela or Russia for energy, and potentially less money spent on the military having to patrol the oil routes.

    BTW, Univ. of Michigan is looking into direct conversion of solar energy into electricity; collect photons of light into an optical cable, switch it on/off, the collapsing field should produce a current in a surrounding coil.

    • If you actually study the subject, you find out that solar doesn’t reduce the usage of other power sources at all. The reason for that is simple. The other power sources have to be kept running in order for them to step in on a moments notice whenever a cloud covers a field of solar cells.

      Solar cells are a direct conversion of solar energy into electricity. Pulsing light does not create a magnetic field. No magnetic field, no electricity. I don’t know where you are getting your information from, but you should demand a refund.

  21. Weighing in belatedly, but with a lot of hard earned solar cell knowledge as a former independent director of an Argonne Labs spinout ‘revolutionary’ solar cell startup. We blew about $5 million.

    The single layer P/N junction limit is called the Shockley Quiessner limit. Depending on how calculated, it is 31-32%, not 29.1. So a theoretical improvement to ~35% is neither as great or as valuable as MIT PRs.

    The SQ theoretical limit can never be reached because of system overheads like current collector lines. The best single cell (monocrystalline) silicon, using every trick in the book like antireflective coatings, diffraction grating surface…) is about 26%. The panels made from those cells run about 22%. These are the most expensive solar cells until you get to space only multilayer P/N GaAs stuff, which Boeing makes only for deep space probes where cost is no object.

    And, a halfnium oxynitride layer only a few atoms thick can only be laid down with present technology using super controlled CVD, which means vacuum processing on small experimental cell scales. Unfortunately, as we found at MOT for FED displays, CVD does not easily scale areally. (We had the worlds largest CVD throw radius machine, custom built, 25 feet, to do 6 inch by 9 inch prototype FED moly spint tip panels (metallic cones inside 1 micron holes). Machine cost $30 million and had to be installed in a custom built wafer fab.) So there is no large volume manufacturing commercial process known.

    So this is a great matsci near quantum physics (all quantum dot few atom phenomena are quantum related) PhD thesis, but nothing for the real world of renewable energy stuff. Reminds me of the organic electrolyte ‘rhubarb’ flow cell battery Harvard reported a few years ago. Essay California Dreaming in ebook Blowing Smoke, foreword from Judith Curry. Of course, nothing since.

  22. Here’s a link to a site that briefly discusses the various types of cells (Triple Junction GaAs, single junction, mono- and polycrystalline silicon, amorphous cells, organic, etc). There is a nice chart by NREL showing efficiency of the various types of cells since 1975. It’s a good primer, but doesn’t show price or extent of commercial development. https://www.costofsolar.com/most-efficient-solar-panels-which-ones/

    • Another damned solar hype piece, Mr. Mosher. What is the cost of the lack of nighttime solar generation? Per MWh costs are meaningless unless the energy is constantly available.

      • “Per MWh costs are meaningless unless the energy is constantly available.”

        Huh, not meaningless to my customers. they love cheap solar.

        This is really simple. the cost of solar is coming down and will continue to come down.
        20% per doubling of production capacity.

        in the USA coal is dead. nobody is building new plants. old plants cant get re licenced.

        • “Huh, not meaningless to my customers. they love cheap solar.” Mr. Mosher, have you gone from hustling cheap Chinese Bitcoin-mining machines to hustling solar power? Are you now praising solar power now the way you praised Bitcoins in the past for pecuniary reasons? That causes me to suspect your motives when you opine on controversial subjects and reference particular analyses (actually sales jobs).

          As I have pointed out in the past, I installed solar on my rooftop because the other Nevada Energy customers in particular and taxpayers in general are paying for it. Is your customers’ love of cheap solar due to taxpayer and utility ratepayer subsidies? [Note: My rooftop solar is also a hedge against anticipated large Nevada Energy rate increases due to insane “renewables” mandate-laws and subsidies.]

          Your customers’ cheap solar is only available because they don’t have to directly pay for the other energy production sources in the electrical system at night; without that support subsidy your customers wouldn’t be so happy. Ultimately, your customers don’t pay for the added electric transmission costs to integrate their far-flung solar power production sites. [That is, unless you are now hustling rooftop solar and not the laughable “pay for solar in your power bill” while receiving electrical energy produced from a myriad of sources.]

          Please source your “20% per doubling of production capacity” cost decreases for FUTURE industrial solar installations. We know that in the past taxpayer and ratepayer subsidies for that unnecessary and immature technology engendered economies of scale. Are similar future economies of scale reasonably anticipated in what is now a mature technology? Or are you just blowing smoke to get more of your “customers” to buy your product.

          Mr. Mosher, I didn’t say anything about your praising Bitcoins while making a profit off them because I believe it is up to individuals whether to make speculative investments. Now, however, you are hustling a product that actually harms others that are not part of the transaction. The harm to such others comes from the requirement that they must pay to support the transaction without their knowledge or acceptance. Socialism at its best.

    • There are hundreds of new coal plants being built in Asia. US plants are closing and/or switching to NatGas, because it is Cheaper! Mosh, as usual, you leave out The Rest Of The Story…

    • Once again Steve is assuming that any trend he approves of will continue indefinitely.
      At present Nat Gas is cheaper than coal. Switching from coal to nat gas for power plants is increasing demand for nat gas and decreasing demand for coal, causing nat gas to go up in price and coal to go down.

      Eventually the two will come back into equilibrium, perhaps the next technological break through will be some method to reduce the cost of mining coal.

  23. The advances made by ingenious engineers and scientists during wars are well documented. I view this as the peacetime equivalent. I don’t really care for the solar panel application but more for the extended possibilities that this type of research brings – a sort of Graphene on steroids. All strength to this and other teams like them.

  24. It’s funny how stupid all the deniers will look in 10 years from now …
    It will be fun to throw mud at them ..

  25. The headline is mis-leading. With this device, UV photons are capable of knocking loose two electrons. Lower energy photons still only knock lose one electron. UV is a pretty small percentage of the total energy in a beam of sunlight.

  26. Alvin Marks – Lumiloid 1986
    Inventor of Polarized Films (sunglasses etc.)
    Refind his polarizing films using different compounds and much finer lines for more than 80% efficient solar cell. Look for video. This development has been buried by someone located in Georgia,

  27. I agree the potential benefit for photovoltaic solar panels is minimal as a slight increase in efficiency at a much greater cost sounds insignificant.Rather, I see the potential for radioactive ion power generation. I foresee portable power sources which derive their energy from Alpha particle emitters and photovoltaic cells.

    • I’m not sure alpha particles would stimulate photovoltaic cells (probably degrade them over some short time), but it is an interesting question if the energy of charged particles from nuclear fission of fusion could be converted to electricity directly without having to heat a substrate, and then use the heat to drive a cycle.

    • re: “Rather, I see the potential for radioactive ion power generation. ”

      How about power generation using MHD? MHD – Magnetohydrodynamic power generation, using a stream of plasma from a source routed up through the ‘collecting electrodes?

      Here is a brief demo of room-temperature liquid metal GaInSn alloy mechanically pumped through a magnetic field and the electrically conductive flow results in the generation of electrical power at two opposing electrodes that are transverse to both the flow and magnetic field direction. Note: This demo does not include the plasma source, which is adapted from the photo-voltaic SunCell reactor previously demonstrated.

      “Magnetohydrodynamic Electric Power Generation Demonstration”

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