Columbia Uni­ver­sity pro­fes­sor de­vel­op­ing new kind of so­lar cell

China Daily (USA) - - TOP NEWS - By PAUL WELITZKIN in New York

When most peo­ple look at a sky­scraper in New York City, they see a tall build­ing with many win­dows. Xiaoyang Zhu sees a po­ten­tial army of so­lar power providers.

Zhu — a pro­fes­sor of chem­istry at Columbia Uni­ver­sity and a na­tive of Suzhou in Jiangsu prov­ince — and a team of re­searchers are de­vel­op­ing a new class of in­gre­di­ents for so­lar-cell pro­duc­tion.

The name for those in­gre­di­ents is a tongue twister: Hy­brid Or­ganic In­or­ganic Perovskites, or HOIPs. But their end-goal is sim­ple: eas­ily achieve largescale and low-cost pro­duc­tion of so­lar cells, as well as greater ef­fi­ciency.

Zhu and the team are us­ing fund­ing from the US De­part­ment of En­ergy and the Na­tional Sci­ence Foun­da­tion to de­velop HOIPs.

“When you look at a sky­scraper in New York City you see hun­dreds of win­dows that are tinted to keep out the sun­light,” Zhu said on Tues­day. “Imag­ine that we work with the glass man­u­fac­tur­ers to re­place the tint on those win­dows and turn them into a so­lar panel. Sud­denly we don’t need to run elec­tric­ity to cool down all of those rooms.”

So­lar cells turn sun­light into elec­tric­ity and most are on pan­els that are made from sil­i­con lay­ers. The process that is used to make the sil­i­con lay­ers is ex­pen­sive and time con­sum­ing. Sil­i­con cells are very frag­ile as even a mi­nus­cule amount of dust or dirt can se­ri­ously re­duce the cells’ ef­fec­tive­ness.

“Th­ese (HOIPs) are a ma­te­rial that you pour out of a so­lu­tion at room tem­per­a­ture which means you can eas­ily achieve large-scale and low-cost pro­duc­tion,” Zhu said.

The other ma­jor ad­van­tage for HOIPs over sil­i­con-pro­duced so­lar cells is in­creased ef­fi­ciency. Zhu said that it took six years for HOIPs to reach a 22 per­cent level of power con­ver­sion ef­fi­ciency. But it took from 50 to 60 years for sil­i­con cells to reach the same level, he added.

There is a draw­back to HOIPs, said Zhu. They con­tain lead and are also wa­ter sol­u­ble. That means the so­lar cells may dis­solve and leak lead. “We haven’t found an al­ter­na­tive to lead yet but it is only a mat­ter of time,” said Zhu.

The team at Columbia has been in­ves­ti­gat­ing HOIPs since 2014. In 2009, sci­en­tists in Ja­pan demon­strated it was pos­si­ble to build so­lar cells out of HOIPs, and that th­ese cells could har­vest en­ergy from sun­light even when they had de­fects.

Zhu said the use of so­largen­er­ated power is grow­ing quickly. He pointed to Ger­many, “which is a coun­try that is not well known for sun­shine. On av­er­age, about 37 per­cent of Ger­many’s elec­tric­ity pro­duc­tion is from re­new­ables”.

Zhu be­lieves that HOIPs can help shift elec­tric­ity pro­duc­tion to re­new­ables like so­lar in the US and China.

“So­lar is a fast-grow­ing sec­tor of the econ­omy and there is no rea­son why we can’t make it an even larger part,” he said.

The team is led by Zhu and also in­cludes Haim­ing Zhu and Kiyoshi Miy­ata, two post­doc­toral fel­lows at Columbia. Other mem­bers in­clude grad­u­ate stu­dents Jue Wang, Prakriti Joshi, Kristo­pher Wil­liams and post­doc Daniel Nies­ner, all of Columbia; Yong­ping Fu and Song Jin, col­lab­o­ra­tors from the Uni­ver­sity of Wis­con­sin Madi­son.

Their re­sults have been re­ported in the jour­nal Sci­ence.

pro­fes­sor of chem­istry, Columbia Uni­ver­sity

Xiaoyang Zhu,

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