A facile method to improve the stability and efficiency of CsPbI2Br perovskite solar cells prepared at low temperature

•The CsPbI2Br solar cell with an efficiency of up to 11.68% with the stabilized output 10.31% at 80 °C by a three-minute spin coating method.•Adding 30ul levulinic acid in the CsPbI2Br perovskite precursor solution to form cubic phase CsPbI2Br at room temperature by three-minute spin coating without any subsequent annealing process.•Levulinic acid added can significantly improve the stability solar cells in air.