Mitigating Intrinsic Interfacial Degradation in Semi‐Transparent Perovskite Solar Cells for High Efficiency and Long‐Term Stability
Syed Dildar Haider Naqvi, Kyungnan Son, Wonzee Jung, Hui Ung Hwang, Sangmin Lee, Arheum Lee, Min-Jong Keum, Sunwook Kim, Jeong Won Kim, Min Gu Kang, Hee‐eun Song, Sungjun Hong, Inyoung Jeong, Seungkyu Ahn, Seungkyu Ahn, Andreas Lambertz, Kaining Ding, Weiyuan Duan, Kanghoon Yim, SeJin Ahn, SeJin Ahn
Abstract
Abstract Conventional semi‐transparent perovskite solar cells (ST‐PSCs) generally exhibit inferior performance and stability relative to opaque PSCs. However, a comprehensive understanding of the origins of inferior performance and stability of ST‐PSCs and a practical solution to these challenges are both lacking. Here, it is shown for the first time that lithium ions from a lithium bis(trifluoromethanesulfonyl)imide (LiTFSI)‐doped 2,2′,7,7′‐tetrakis[N,N‐di(4‐methoxyphenyl)amino]−9,9′‐spirobifluorene (Spiro‐MeOTAD) hole‐transport layer (HTL) can diffuse into the molybdenum trioxide buffer layer at their interface, yielding ST‐PSCs with lower efficiency and accelerated degradation. It is also demonstrated that this undesired Li‐ion diffusion can be avoided by HTL surface modification with stable lithium oxides. Using this approach, the constructed ST‐PSC exhibits a new record power conversion efficiency (PCE) of 22.02% (21.68% certified) and a fill factor of >80%, with >99% shelf‐stability after 400 h and >99% operational stability for 240 h, which clears away this longstanding limitation of the performance and stability of ST‐PSCs. This strategy is also applied to fabricate four‐ and two‐terminal perovskite/silicon tandem solar cells with bifacial equivalent efficiencies of 31.5% and 26.34%, respectively, at 20% albedo.