Tuning the Optoelectronic Property of All‐Inorganic Lead‐Free Perovskite via Finely Microstructural Modulation for Photovoltaics

Abstract Bismuth‐based halide perovskite materials have attracted extensive attention for optoelectronic applications due to nontoxicity and ambient stability. However, limited by low‐dimensional structure and isolate octahedron arrangement, the undesirable photophysical properties of bismuth‐based perovskites are still not well modulated. Here, the rational design and synthesis of Cs 3 SbBiI 9 with improved optoelectronic performance via premeditatedly incorporating antimony atoms with a similar electronic structure to bismuth into the host lattice of Cs 3 Bi 2 I 9 is reported. Compared with Cs 3 Bi 2 I 9 , the absorption spectrum of Cs 3 SbBiI 9 is broadened from ≈640 to ≈700 nm, the photoluminescence intensity enhances by two orders of magnitude indicating the extremely suppressed carrier nonradiative recombination, and the charge carrier lifetime is further increased from 1.3 to 207.6 ns. Taking representative applications in perovskite solar cells, the Cs 3 SbBiI 9 exhibits a higher photovoltaic performance benefiting from the improved intrinsic optoelectronic properties. Further structure analysis reveals that the introduced Sb atoms regulate the interlayer spacing between dimers in c ‐axis direction and the micro‐octahedral configuration, which correlate well with the improvement of optoelectronic properties of Cs 3 SbBiI 9 . It is anticipated that this work will benefit the design and fabrication of lead‐free perovskite semiconductors for optoelectronic applications.