Abstract
Despite the rapid progress in inorganic cesium lead halide perovskite (CsPbX 3 ) materials originating from excellent thermal stability; their poor phase stability at room temperature and lower efficiency compared to organic-inorganic counterparts still limit their development toward commercialization. Recently, Pb-site doping of inorganic perovskites stand outs for the improvement of aforementioned issues for emerging photovoltaic applications. Herein, we introduce a compositional engineering approach to tune the CsPbI 2 Br crystallization by directly incorporating iron (II) chloride (FeCl 2 ) into perovskite precursor. The small amount of FeCl 2 stabilizes the black α-phase to avoid the undesirable formation of the non-perovskite phase owing to Fe 2+ induced grain size reduction. Besides, the FeCl 2 incorporation thoroughly align the energy level, promote the built-in potential ( V bi ), and reduce the defect states in the perovskite, resulting in a record power conversion efficiency (PCE) of 17.1% with a remarkable open-circuit voltage ( V OC ) of 1.31 V. More importantly, FeCl 2 -doped CsPbI 2 Br-based devices exhibit an exceptional operational stability with a retention of over 95% initial PCE after 330 h at maximum power point (MPP) tracking. • A compositional engineering approach based on iron (II) chloride (FeCl 2 ) stabilizes the photoactive α-phase. • FeCl 2 incorporation thoroughly align the energy level, promote the built-in potential, and reduce the defect states. • A record efficiency of 17.1% was thoroughly achieved in a planar architecture with a remarkable open-circuit voltage ( V OC ) of 1.31 V. • FeCl 2 -doped CsPbI 2 Br-based devices exhibit an exceptional operational stability with a retention of over 95% after 330 h.
Published Version
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