Capsaicin Spices Up Perovskite-Based Solar Cells To Record Efficiencies

'Researchers claim achievement of new record photovoltaic conversion efficiencies for perovskite-based solar cells by spicing them up with a little capsaicin,' writes Slashdot reader ffkom, adding: 'Of course everyone who loves to eat chilis already knew capsaicin energizes you to record levels.' The researchers have published their findings in the journal Joule. From the report: Perovskite solar cells (PSCs) suffer from significant nonradiative recombination, limiting their power conversion efficiencies. Here, for the first time, we directly observe a complete transformation of perovskite MAPbI 3 surface region energetics from p- to n-type during defect passivation caused by natural additive capsaicin, attributed to the spontaneous formation of a p-n homojunction in perovskite active layer. We demonstrate that the p-n homojunction locates at 100 nm below perovskite surface. The energetics transformation and defect passivation promote charge transport in bulk perovskite layer and at perovskite/PCBM interface, suppressing both defect-assisted recombination and interface carrier recombination. As a result, an efficiency of 21.88% and a fill factor of 83.81% with excellent device stability are achieved, both values are the highest records for polycrystalline MAPbI 3 based p-i-n PSCs reported to date. The proposed new concept of synergetic defect passivation and energetic modification via additive provides a huge potential for further improvement of PSC performance.

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