β-Diketone Coordination Strategy for Highly Efficient and Stable Pb–Sn Mixed Perovskite Solar Cells
Ruyue Wang, Huaizhi Gao, Runnan Yu, Haoran Jia, Zongwen Ma, Zhang-Wei He, Yuling Zhang, Jing Yang, Lei Zhang, Zhan’ao Tan
Abstract
The narrow bandgap Pb–Sn hybrid perovskite materials with lower toxicities and adjustable optical bandgaps provide the opportunity to construct high-efficiency perovskite solar cells (PerSCs). To solve the issues of the uncontrollable crystallization rate of Pb–Sn perovskite and easy oxidation of Sn2+, a β-diketone-based additive, N,N,N′,N′-tetraphenylmalondiamide (TPMA), is introduced to coordinate with Pb2+ and Sn2+. The introduction of TPMA can improve the morphology of perovskite films and decrease the density of defect states, resulting in an enhanced power conversion efficiency of >20% and improved stability. The PerSC without encapsulation retains 94% of its initial efficiency after being stored for 1000 h in a nitrogen-filled glovebox and shows a lifetime of only 8% degradation after being continuously heated for 100 h at 80 °C. This work represents a new strategy of introducing a β-diketone ligand as an additive in precursor engineering for achieving efficient and stable PerSCs.