Inorganic and Lead-Free AgBiI₄ Rudorffite for Stable Solar Cell Applications

Organic–inorganic hybrid lead halide perovskites have recently realized significant development. However, the toxicity of lead (Pb) and the poor stability might eventually hamper the commercialization of perovskite solar cells (PSCs). Here, we present an environment friendly and stable all inorganic rudorffite AgBiI4 as solar absorber by solution-based synthesis of thin-films. AgBiI4 films fabricated by 0.6 M solution and annealed at 150 °C show dense grains and high surface coverage. Furthermore, the AgBiI4 films exhibit greater thermal stability and photostability than CH3NH3PbI3. Ultimately, by judiciously choosing the hole transport material with appropriate energy level, the solar cell device demonstrates high carrier extraction efficiency and achieve a power conversion efficiency (PCE) of 2.1% under standard 1 sun (AM 1.5). The devices also show excellent long-term air stability and still maintain 96% of its initial PCE even after 1000h at relative humidity of 26%. This work highlights new directions for further exploration of Pb-free and stable solar cells.