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

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 similar to 10 nm. Varying the composition in CsPbBrxI3-x it was observed that CsPbBr1.5I1.5 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 CsPbBr1.5I1.5 showed power conversion efficiency (PCE) similar to 7.94% with open circuit voltage similar to 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 CsPbBr1.5I1.5 composition. Moreover this composition offers nearly hysteresis free perovskite device.