Enhanced Thermal and Photostability of Perovskite Solar Cells by a Multifunctional Eu (III) Trifluoromethanesulfonate Additive
Heng Liu, Yueyue Gao, Fuzong Xu, Xuechun Zhang, Asmat Ullah, Lujia Xu, Shanshan Zhang, Jiantao Wang, Stefaan De Wolf, Hsing‐Lin Wang
Abstract
Abstract Perovskite solar cells (PSCs) have witnessed a meteoric rise in device performance. However, maintaining photostability, particularly under thermal stress, remains a challenge due to defect formation in the perovskite layer. This study introduces europium (III) trifluoromethanesulfonate [Eu(OTF) 3 ] as a multifunctional additive in two‐step processed perovskite films, significantly improving the performance and high‐temperature photostability of n‐i‐p PSCs. Density function theory (DFT) calculations reveal that the OTF − anion strongly coordinates with Pb 2+ , effectively inhibiting iodine vacancy defect formation. The addition of Eu(OTF) 3 promotes perovskite grain growth to ≈2 µm and enhances film crystallinity. PSCs with a structure of ITO/SnO 2 /perovskite/PDCBT/NiO x /Au achieve a champion power conversion efficiency (PCE) of 23.8%. Under 85 ± 5 °C and 1 sun illumination at an open circuit in ambient air, the PSCs with Eu(OTF) 3 retain 82% of their initial PCE after aging for 1500 h.