Water assisted formation of highly oriented CsPbI2Br perovskite films with the solar cell efficiency exceeding 16%. Issue 34 (13th August 2020) - Lin, Ze Qing
Abstract : Oriented, large grain-sized CsPbI2 Br perovskite films with a solar cell efficiency over 16% were achieved via a synergistic effect of strong polar solvents. Abstract : Cesium lead halide perovskites are promising alternatives as light-absorbing materials for achieving perovskite solar cells with excellent thermal stability, but their inferior power conversion efficiency (PCE) and ambient instability are impeding their application. In this work, we show that liquid water can assist the formation of CsPbI2 Br perovskites under the synergetic adsorption of H2 O and dimethylsulfoxide (DMSO), which enabled uniform, [100] oriented CsPbI2 Br films with a grain size up to 4.4 μm. It was found that a suitable amount of H2 O helps desorb the DMSO molecules, and thus favours the formation of a cubic perovskite phase from DMSO complexed intermediates. Perovskite solar cells based on our strategy delivered an optimized PCE of 16.47% with a high open-voltage of 1.33 V, as well as good device stability against humidity, light and heat.