A trick of light: UC Irvine researchers turn silicon into direct bandgap semiconductor
https://news.uci.edu/2024/10/31/a-trick-of-light-uc-irvine-researchers-turn-silicon-into-direct-bandgap-semiconductor/A trick of light: UC Irvine researchers turn silicon into direct bandgap semiconductor
Discovery enables manufacturing of ultrathin solar panels, advanced optoelectronics
Irvine, Calif., Oct. 31, 2024 — By creating a new way for light and matter to interact, researchers at the University of California, Irvine have enabled the manufacturing of ultrathin silicon solar cells that could help spread the energy-converting technology to a vast range of applications, including thermoelectric clothing and onboard vehicle and device charging.
…
Co-author Ara Apkarian, UC Irvine Distinguished Professor emeritus of chemistry, said: “This phenomenon fundamentally changes how light interacts with matter. Traditionally, textbooks teach us about so-called vertical optical transitions, where a material absorbs light with the photon changing only the electron’s energy state. However, momentum-enhanced photons can change both the energy and momentum states of electrons, unlocking new transition pathways we hadn’t considered before. Figuratively speaking, we can ‘tilt the textbook,’ as these photons enable diagonal transitions. This dramatically impacts a material’s ability to absorb or emit light.”
According to the researchers, the development creates an opportunity to exploit recent advances in semiconductor fabrication techniques at the sub-1.5-nanometer scale, which has the potential to affect photo-sensing and light-energy conversion technologies.
“With the escalating effects of climate change, it’s more urgent than ever to shift from fossil fuels to renewable energy. Solar energy is key in this transition, yet the commercial solar cells we rely on are falling short,” Potma said. “Silicon’s poor ability to absorb light means that these cells require thick layers – almost 200 micrometers of pure crystalline material – to effectively capture sunlight. This not only drives up production costs but also limits efficiency due to increased charge carrier recombination. The thin-film solar cells that are one step closer to reality due to our research are widely seen as the solution to these challenges.”
…
= new reply since forum marked as read
The unit of energy is the Joule, not the Watt. Yet, most claims about how fast solar and wind junk is spread across industrial parks carved out of wilderness, deliberately treat unreliable solar and wind as the equivalent of nuclear power plants, the most reliable energy producing devices on the planet.
Personally I oppose short lived crap that spews microplastics into the atmosphere, but that's just me.
This may come as a surprise, but the capacity utilization of wind and solar is seldom more than 30%. It's widely reported and generally accepted that sunlight is available for only a part of the 24 hour day, and the wind doesn't blow continuously. For the other 70% of the time, advocates for solar and wind have no problem with burning fossil fuels. They just couldn't give a shit about fossil fuels, because, in fact, the use of solar and wind depends on them.
Evidence:
Nuclear powered France:
Coal burning antinuke hell, Germany:
These are annualized figures (2023) available at Electricity Map
The current graphic, as of this writing, 11/07/2024 9 pm EST (US) is particularly illustrative:
In "percent talk" it appears that the climate gas intensity of Germany is 1106% higher than that of France, not that I expect the fossil fuel coddling apologists for the trillion dollar solar and wind hype to give a rat's ass about that fact.
As for China building 500% more transitory solar and wind junk, I'm sure that I assumed to be gullible and stupid enough to not understand the difference between a peak Watt and a Joule, but I'm no longer offended by this dishonest slight of hand, although I am disturbed to see what this dishonest rhetoric has done to the planet, leaving it in flames. For the record, in my scientific environmental reading, a prodigiously observed habit I've embraced for decades, I fully understand that in every LCA (Life Cycle Analysis) paper, the lifetime of infrastructure is included. This shows, again and again, that the climate intensity of solar and wind energy, not to mention the mass and land intensity, do not, and never will, match nuclear energy for cleanliness and sustainability. In my opinion, solar and wind, lipstick on the fossil fuel pig. They are not, and never were, about preventing the extreme global heating now burning the planet.
As for lifetime, again, always included in LCA calculations:
China's nuclear reactors will be serving humanity a the dawn of the 22nd century approaches, if not well into it with refurbishing, well over half a century after every wind turbine blade and every solar cell on this planet will have been landfill, some of it quite toxic, for half a century.
Thanks for taking my mind off the political tragedy, by the way. I'm pleased with myself for adjusting my ignore list here to point, once again, to the difference between a Watt and a Joule. I feel slightly, but not entirely, better. On some level its disturbing that this distinction, between the Watt and the Joule, which should be covered in high school, still gets by, but offering a correction is a distraction from a dire reality, the worst being the collapse of the planetary atmosphere, followed by the disgusting practices of the American electorate.
Nevertheless, it's tiresome now, so I'll quit it; this late in the game there's no point to trying to address dogma.
Have a nice evening.
I have in my electronic files almost every issue of the World Energy Outlook, and each year I use the data tables (which also contain soothsaying) for the most current issue in my posts. Here's this year's:
World Energy Outlook 2024
Table A.1a: World energy supply Page 296, showing the primary energy available as of 2023 compared to 2022.
I can and do reproduce this table as often as required to confront ignorance.
I would not be surprised to hear someone claim that 8 + 8 is greater than 30. The first 8 is the amount of energy produced at a trillion dollar cost for solar energy, the second 8 for wind, (which grew by zero percent between 2022 and 2023), and the thirty is what nuclear energy has been producing in an atmosphere of mindless vituperation for roughly three decades, saving lives and about two years worth of annual dumping dumping of the dangerous fossil fuel waste carbon dioxide.
Prevented Mortality and Greenhouse Gas Emissions from Historical and Projected Nuclear Power (Pushker A. Kharecha* and James E. Hansen Environ. Sci. Technol., 2013, 47 (9), pp 4889–4895)
The WEO "scenarios" if one looks back over the decades are both disturbing and amusing.
I agree that antinuke ignorance has prevented nuclear from doing what it might have done, but whatever humanity does going forward, albeit clearly too little, too late, can at least slow the growth of dependence of fossil fuels.