Ternary Halogen Doping for Efficient and Stable Air‐Processed All‐Inorganic Perovskite Solar Cells

Abstract

Metal halide perovskites have emerged as the revolutionary semiconductor material in the field of various optoelectronic applications, among which perovskite solar cells (PSCs) have raced to the front in the third-generation photovoltaics. Notably, the single-junction PSCs based on organic-inorganic hybrid perovskites have recently achieved certified power conversion efficiency (PCE) of 25.5%. [1] However, organic-inorganic hybrid perovskites suffer from the long-term instability problem due to the presence of organic component that is sensitive to unfavorable conditions, including moisture, UV light, oxygen, and temperature. [2] To overcome this deficiency, all-inorganic perovskites (i.e., CsPbI 3 ) have drawn much attention mainly owing to their superior thermal stability [3] and high theoretical PCE of 28%. [4] However, the stability of CsPbI 3 with cubic phase (also known as α-phase or black phase) is shown to be poor under ambient conditions because of the spontaneous phase transition from photoactive cubic phase into orthorhombic non-perovskite δ-phase. [5] Therefore, the improvement of phase stability is of primary significance to achieve efficient and stable all-inorganic PSCs.Since 2015, great efforts have been made to develop effective strategies to stabilize the α-phase of CsPbI 3 perovskite, [6][7][8] such as precursor solution engineering, [9][10][11][12] compositional engineering, [13][14][15] interface engineering, [16][17][18][19][20] dimensional engineering. [21][22][23][24][25] These strategies are found to not only enhance the stability but also boost the PCE of the PSCs by improving the quality of all-inorganic perovskite film. Very recently, record-high PCE of 20.8% has been achieved in CsPbI 3 -based PSCs by developing the rational surface-defect control strategy, demonstrating the great promise of all-inorganic PSCs. [26] However, the currently adopted fabrication processes of all-inorganic CsPbI 3 perovskite film are strictly in an inert atmosphere to ensure the production of high-performing PSCs, which greatly impedes their feasibility in large-scale production. Recently, Br-based allinorganic perovskites have also been investigated due to the superior stability and high open-circuit voltage the device could achieve, [27][28][29][30][31][32][33] suggesting the great potential of halogen-doping strategy in enhancing the stability of all-inorganic perovskites.

Nanometer-Thick CsPbBr3 Films with Embedded CsPb2Br5 Nanowires for Photodetector Applications

“…Currently, numerous research studies indicate that the composite structure of CsPb 2 Br 5 and CsPbBr 3 perovskites holds potential advantages for addressing the performance degradation of CsPbX 3 perovskites caused by external factors. − The fabrication of multidimensional composite films by vapor deposition as a common method could prevent the impact of solvents on the solubility of the underlying thin film. , This method is suitable for fabricating dual-phase composite materials of 2D CsPb 2 Br 5 and three-dimensional (3D) CsPbBr 3 . − Moreover, the majority of perovskite devices are made using thin film structures. The defects and grain boundaries present in these films frequently result in subpar optoelectronic performance of perovskite thin film devices. − Compared to bulk or planar materials, nanowires provide a larger surface area that facilitates more efficient light absorption. Moreover, the constraints imposed by the wire-like structure enable better control of the direction of charge carrier transport, thereby reducing potential losses during exciton transport. , For example, Shin et al introduced CsPbBr 3 –CsPb 2 Br 5 biphasic perovskite nanowires as an interlayer in perovskite solar cells, achieving effective charge carrier transport within the device.…”

Dual‐Doping Strategy of Metal Chlorides in Ambient Air with High Humidity for Achieving Highly Air‐Stable All‐Inorganic Perovskite Solar Cells

“…[9] Additionally, the optimized CsPbI 3 PSC with the PCE of 17.51% was fabricated under ambient air by introducing a new precursor solvent (MAAc) and doping ternary halogen to regulate the crystallization process. [10] The ionic radius should meet the requirement of Goldschmidt's empirical tolerance factor (t…”

“…[ 9 ] Additionally, the optimized CsPbI 3 PSC with the PCE of 17.51% was fabricated under ambient air by introducing a new precursor solvent (MAAc) and doping ternary halogen to regulate the crystallization process. [ 10 ] The ionic radius should meet the requirement of Goldschmidt's empirical tolerance factor (…”