Magnesium acetate additive enables efficient and stable carbon electrode based CsPbI2Br perovskite solar cells

Carbon electrode based hole transporting materials (HTM) free CsPbI 2 Br perovskite solar cells have advantages of excellent thermal stability and low cost. However, it is still a challenge to provide an effective strategy to realize highly efficient and stable HTM-free devices. Herein, a small amount (0.2–0.5% vs Pb source) of magnesium acetate (Mg(Ac) 2 ) was introduced into the CsPbI 2 Br precursor solution. It was demonstrated that the carbonyl groups of Mg(Ac) 2 can bind with all intrinsic elements of CsPbI 2 Br, leading to improved crystallinity and passivation of defects. Therefore, the power conversion efficiency of HTM-free devices was increased from 10.84% to 13.08%, along with an enhancement in device stability.