Dependence of halide composition on the stability of highly efficient all-inorganic cesium lead halide perovskite quantum dot solar cells

Abstract All-inorganic perovskites suffer from low temperature phase instability and degradation under moisture and polar solvents. Here we have synthesized organic ligand assisted stable perovskite quantum dots (QDs) with uniform size ~10 nm. Varying the composition in CsPbBr x I 3- x it was observed that CsPbBr 1.5 I 1.5 could be an alternative solution for stable perovskite QDs. Photoluminescence (PL) decay showed comparable average lifetime useful for photovoltaic (PV) application. The photovoltaic devices made from CsPbBr 1.5 I 1.5 showed power conversion efficiency (PCE) ~7.94% with open circuit voltage ~ 1.0 V, fill factor 0.70 and long term stability. This PCE is also the highest as compared to other PV reports for QDs with CsPbBr 1.5 I 1.5 composition. Moreover this composition offers nearly hysteresis free perovskite device.