Efficient and Stable CsPbI₂Br Inorganic Perovskite Solar Cell Co-Modified with Ionic Liquids and Quantum Dots

The all-inorganic CsPbI 2 Br perovskite possesses outstanding thermal stability as a light absorber in perovskite solar cells (PSCs) or photodetectors. Still, their sensitivity to moisture induces irreversible decomposition and a large number of halogen vacancy defects, hindering their commercial applications. Herein, by incorporating 1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF 4 ) ionic liquids (ILs) as a precursor additive, a CsPbI 2 Br light absorber with an improved carrier lifetime and reduced trap density is achieved. Moreover, the modification of the perovskite surface with CsPbBr 3 quantum dots (QDs) further improved the efficiency and moisture stability of the PSC. As a result, the BMIMBF 4 IL and CsPbBr 3 QD co-modified PSC achieves a maximum power conversion efficiency (PCE) of 15.37% and retained 80% of its initial PCE after exposure to ambient air for 60 h. This work proposes a synergistic approach for developing high-performance organic-free PSCs with an improved PCE and moisture stability.