Indium-Doped CsPbI_2.5Br_0.5 with a Tunable Band Structure and Improved Crystallinity for Thermo-Stable All-Inorganic Perovskite Solar Cells

Hybrid organic-inorganic halide perovskite solarcells (PSCs)have garnered significant attention in the field of photovoltaics.Despite the rapid advancements in photoelectric conversion efficiency(PCE), the sensitivity of hybrid perovskites to moisture and heatposes challenges to device stability. All-inorganic PSCs (AIPSCs)eliminate the use of traditional organic components, resulting insignificantly extended operational lifetimes. Herein, we report thedoping of indium bromide (InBr3) into the lattice of CsPbI2.5Br0.5-based all-inorganic perovskites, leadingto large crystalline grain sizes and tunable energy band levels byadjusting the concentration of InBr3 dopants. AIPSCs basedon highly stable In-doped CsPbI2.5Br0.5 absorberlayers can be conveniently fabricated in an ambient air environment.Moreover, screen-printable nanocarbon counter electrodes with highstability and low cost are introduced to replace unstable organichole-transport materials and expensive noble metal electrodes, thusfurther increasing ambient stability and greatly reducing device costs.As a result, the In-doped CsPbI2.5Br0.5-basedAIPSCs achieve a champion PCE of 12.05% and favorable heat endurancewith a PCE retention of 80% after being continuously heated at 100 & DEG;C for over 1632 h. This work provides a feasible strategy oflattice doping to tackle the intractable issue regarding the intrinsicthermal instability of inorganic perovskite materials for fabricatingAIPSCs with a wide absorption range and high environmental stability.