A facile method to improve the stability and efficiency of CsPbI_2Br perovskite solar cells prepared at low temperature

摘要

CsPbI2Br has become the focus of researchers in recent years due to its excellent thermal stability compared to the organic-inorganic hybrid perovskites. However, it requires high temperature to form cubic phase, and it is difficult to maintain the cubic phase in the high humidity ambient. By adding 30 mu L levulinic acid (LA) to the CsPbI2Br precursor solution, cubic phase CsPbI2Br can be obtained by spin-coating three minutes (TMS) at room temperature (RT) instead of high temperature. Based on the TMS, highly quality cubic phase CsPbI2Br film can be obtained at 80 degrees C annealing temperature, the stability of cubic phase CsPbI2Br can be significantly improved by adding LA in the CsPbI2Br precursor solution. Based on this, CsPbI2Br cells without LA achieve 11.68% power conversion efficiency (PCE) at low temperature of 80 degrees C and the corresponding stabilized power output is 10.31%. Furthermore, 10 mu L LA addition CsPbI2Br cells keep its 50% PCE after 10 days under 35%RH and RT. This has found a new way to improve the stability of inorganic perovskite solar cells, and increasing its potential in flexible solar cells.