Marrying two types of solar cells draws more power from the sun

[OKIsItJustMe]

https://www.sciencemag.org/news/2019/04/marrying-two-types-solar-cells-draws-more-power-sun

Marrying two types of solar cells draws more power from the sun

By Robert F. ServiceApr. 10, 2019 , 4:30 PM

ORLANDO, FLORIDA—The promising solar cell materials called perovskites need a partner. Researchers marry a layer of perovskite, which absorbs high-energy blue photons in sunlight, with standard silicon, which gobbles up lower-energy light. In theory, such tandem cells should deliver a double dose of power, with electricity coming from both layers. But building two complete solar cells, one atop the other, adds cost and other challenges. Last week, a team reported advancing a potentially simpler, cheaper way to make a tandem.

The team's perovskite converts light instead of generating current, transforming blue photons to near-infrared (near-IR) photons, which the silicon cell below then turns into electricity. The researchers say the design could boost the efficiency of silicon solar cells by nearly 20%. If it does, it could be key to realizing the promise of perovskites, a class of compounds that share a crystal structure and are made from common elements such as lead, bromine, and chlorine.

"This is one of the most exciting results I've seen in a long time," says Michael McGehee, a perovskite expert at Stanford University in Palo Alto, California. "The boost in efficiency they are claiming is very significant." Silicon solar cell–makers, a $30 billion a year industry in 2016, grasp at every tenth of a percentage point gain in efficiency.

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In the resulting tandem, nearly all the blue light absorbed by the perovskite is converted to near-IR photons, Gamelin reported. As a result, he predicts, topping a high-end silicon cell with the ytterbium perovskite should enable it to convert 32.2% of the energy it absorbs as sunlight into electricity, up from 27%—a 19.2% boost. Gamelin's team is doing experiments now to confirm those predictions. "I am a little skeptical of the numbers," McGehee says. But even a fraction of that increase "would be a big deal," he says.

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[NNadir]

1. The most efficient perovskite solar cells are...

...cesium hexaiodoplumbates, that is lead based compounds.

Here's one of many hundreds of not thousands of descriptions of making this shit:

2.4. Synthesis of CsPbBrxCl3?x and CsPbIxBr3?x QDs. Typically, in a 100 mL three-neck flask, 0.4 mmol PbX2 (0.0745 g of PbBr2 and 0.0556 g of PbCl2 for CsPbBr1.5Cl1.5 perovskite QDs, 0.0922 g of PbI2 and 0.0745 g of PbBr2 for CsPbI1.5Br1.5 perovskite QDs, and 0.0489 g of PbBr2 and 0.0742 g of PbCl2 for CsPbBr1Cl2 perovskite QDs, etc.) was added, followed by the addition of 24 mL of ODE. After a 30 min stirring under argon flowing at room temperature, this mixture was heated to 120 °C for another 30 min. Then OA (1 mL) and OAm (3 mL) were injected into the reaction bottle by a syringe needle. After a few seconds’ stirring, the PbX2 could be completely solubilized and a clear solution was obtained. Then, the temperature was raised to 180 °C and the cesium oleate precursor (2 mL) was quickly injected. After a designed reaction time, the growth of the NPs was terminated and the reaction mixture was cooled down by an ice?water bath for the next purification process. Simply, the obtained NPs were centrifuged by adding about 30 mL of toluene at 9000 rpm (a centrifugal force of 9000g) for 10 min. After centrifugation, the supernatant was poured off and the NPs at the bottom of the centrifuge tube were redispersed in hexane. This purification process was repeated twice. After the purification, NPs were stored as dispersion in hexane or chloroform.

Highly Controllable and Efficient Synthesis of Mixed-Halide CsPbX3 (X = Cl, Br, I) Perovskite QDs toward the Tunability of Entire Visible Light (Su et al, ACS Appl. Mater. Interfaces, 2017, 9 (38), pp 33020–33028)

Putting lead compounds on roofs, distributing lead widely, this for a sun god fantasy, should go along way toward establishing wider neutrotoxic lead contamination, assuring more stupidity in the future.

This fantasy is not even close to being good news for the environment. It is in fact quite the opposite, Trumpian scale doublespeak, a statement of a proposal for an environmental nightmare masquerading as "green."