化学
三碘化物
甲脒
粉末衍射
介电谱
钙钛矿(结构)
活动层
钙钛矿太阳能电池
太阳能电池
能量转换效率
分析化学(期刊)
光电子学
图层(电子)
化学工程
物理化学
结晶学
材料科学
电化学
有机化学
工程类
薄膜晶体管
电解质
色素敏化染料
电极
作者
Monojit Bag,Lawrence A. Renna,Ramesh Adhikari,Supravat Karak,Feng Liu,Paul M. Lahti,Thomas P. Russell,Mark Tuominen,D. Venkataraman
摘要
Solar cells fabricated using alkyl ammonium metal halides as light absorbers have the right combination of high power conversion efficiency and ease of fabrication to realize inexpensive but efficient thin film solar cells. However, they degrade under prolonged exposure to sunlight. Herein, we show that this degradation is quasi-reversible, and that it can be greatly lessened by simple modifications of the solar cell operating conditions. We studied perovskite devices using electrochemical impedance spectroscopy (EIS) with methylammonium (MA)-, formamidinium (FA)-, and MA(x)FA(1-x) lead triiodide as active layers. From variable temperature EIS studies, we found that the diffusion coefficient using MA ions was greater than when using FA ions. Structural studies using powder X-ray diffraction (PXRD) show that for MAPbI3 a structural change and lattice expansion occurs at device operating temperatures. On the basis of EIS and PXRD studies, we postulate that in MAPbI3 the predominant mechanism of accelerated device degradation under sunlight involves thermally activated fast ion transport coupled with a lattice-expanding phase transition, both of which are facilitated by absorption of the infrared component of the solar spectrum. Using these findings, we show that the devices show greatly improved operation lifetimes and stability under white-light emitting diodes, or under a solar simulator with an infrared cutoff filter or with cooling.
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