In recent years, organic lead halide perovskite materials have attracted much attention due to their outstanding optoelectric properties and low manufacturing cost. To improve the stability of perovskite solar cells, inorganic perovskite materials have raised people's attention. Inorganic CsPbX₃(x for halide) perovskite has been demonstrated as promising material for solar cells owing to the superb photoelectronic property and composition stability. However, the low stability of perovskite phase CsPbX₃ with an appropriate band gap under ambient environment hinders its practical application.
Here, we explored new methods for synthesizing inorganic perovskite materials and optimizing the device stability through dimensional engineering. (1) For 3D perovskites, we present an in-depth investigation of the so-called stable ‘α-CsPbI₃,’ we unambiguously determine the existence of DMAPbI₃ synthesized from the popular fabrication process--dissolving PbI₂ in DMF with addition of HI--due to the hydrolysis of DMF. To avoid any involvment of potential organic components through solution processing, we took the advantage of evaporation technique and further designed a high-throughput vapor deposition method to prepare all-inorganic CsPbI₃ perovskite solar cells. We successfully achieved efficient CsPbI₃ PSCs with a champion PCE of 16.3%, which is the higest reported value for all vapour-deposited inorganic PSCs. (2) In 2D system, we tailored the three-dimension CsPbI₃ perovskite into quasi-two-dimensional Cs_xPEA_1-xPbI₃ perovskite. The resultant Cs_xPEA_1-xPbI₃ film demonstrated high thermal stability that it can remain in α phase up to 250°C. (3) In 0D system, we focused on preparing stable 0D quantum dots with superior optoelectronic properties. Afterward, their stability against polar solvent, the effect of excition-phonon coupling on hot carrier dynamics and the process of charge transfer are comprehensively investigated. Our findings offer new insights into the preparation inorganic perovskite materials and provide effective strategies in achieving CsPbX₃-based solar cells with improved efficiency and stability.

Mingzhen Liu

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