Scientists from Skoltech, Institute for Problems of Chemical Physics of RAS and MSU explored the potential of all-inorganic perovskite CsPbI₃ as a photoactive material for planar junction solar cells. They have shown that high-quality perovskite films can be grown by thermal co-evaporation of precursor binary iodides CsI and PbI₂, which represents a clean and scalable technology. The fabricated devices delivered power conversion efficiency (PCE) of 10.5%, thus coming close to the reference system based on conventional methylammonium-lead iodide MAPbI₃ (PCE~12%). These results emphasize that all-inorganic lead halide perovskites can successfully compete in terms of photovoltaic performance with the most widely used hybrid perovskites such as MAPbI₃. Researchers expect that all-inorganic perovskite solar cells will show substantially improved operation stability and deliver sufficiently long lifetimes required for industrial application of this photovoltaic technology. 

Hybrid organic-inorganic “perovskite” solar cells have demonstrated impressive power conversion efficiencies of >22% on the best laboratory samples, thus coming very close to the advanced silicon-based technologies. However, commercialization of these hybrid perovskite photovoltaics is hampered severely by very poor stability of these devices under realistic solar cell operational conditions. Hybrid perovskites incorporating organic cations undergo facile and rapid thermal and photochemical decomposition, which challenges their practical implementation in solar modules.

All-inorganic perovskites (e.g. CsPbBr₃ and CsPbI₃) show outstanding robustness and stability to thermal-induced chemical degradation mechanisms and photochemical-induced bleaching processes, while their solar cell performances generally remain diminished compared to the conventional hybrid perovskite materials such as CH₃NH₃PbI₃. For instance, the CsPbI₃ perovskite films grown from solution delivered solar cells efficiencies of just 2-3%

Pavel Troshin, one of the authors, Skoltech Center for Electrochemical Energy Storage: “In this study, we have demonstrated efficient planar heterojunction solar cells based on all-inorganic CsPbI₃ perovskite films produced by thermal co-evaporation of CsI and PbI₂. These devices showed maximal power conversion efficiencies exceeding 10%, good reproducibility and reasonably low hysteresis in current-voltage characteristics. Reference samples based on CH₃NH₃PbI₃ films delivered just slightly higher performances of 10-12% in the same device configuration. These results demonstrate that all inorganic perovskites can deliver competitive photovoltaic performances thus paving routes to design of novel materials for efficient and stable perovskite-based photovoltaics.”

This work was published in Journal of Physical Chemistry Letters.

 

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