Dimensional Engineering of a Graded 3D–2D Halide Perovskite Interface Enables Ultrahigh Voc Enhanced Stability in the p‐i‐n Photovoltaics

• Published in: Advanced energy materials 2017-10, Vol.7 (20), p.n/a
• Main Authors: Bai, Yang, Xiao, Shuang, Hu, Chen, Zhang, Teng, Meng, Xiangyue, Lin, He, Yang, Yinglong, Yang, Shihe
• Format: Article
• Language: English
• Subjects: blocking ion migration; Charge transport; dimensional engineering; Energy conversion efficiency; energy level alignment; enhanced stability; Interface stability; Photovoltaic cells; reduced interfacial charge recombination; Solar cells; Thermal stability
• ISSN: 1614-6832; 1614-6840
• DOI: 10.1002/aenm.201701038

2D halide perovskite materials have shown great advantages in terms of stability when applied in a photovoltaic device. However, the impediment of charge transport within the layered structure drags down the device performance. Here for the first time, a 3D–2D (MAPbI3‐PEA2Pb2I4) graded perovskite interface is demonstrated with synergistic advantages. In addition to the significantly improved ambient stability, this graded combination modifies the interface energy level in such a way that reduces interface charge recombination, leading to an ultrahigh Voc at 1.17 V, a record for NiO‐based p‐i‐n photovoltaic devices. Moreover, benefiting from the graded structure induced continuously upshifts energy level, the photovoltaic device attains a high Jsc of 21.80 mA cm−2 and a high fill factor of 0.78, resulting in an overall power conversion efficiency (PCE) of 19.89%. More importantly, it is showed that such a graded interface structure also suppresses ion migration in the device, accounting for its significantly enhanced thermal stability. A designer cross‐dimensional perovskite–perovskite (3D–2D) interface upshifts the energy level toward the surface, pronouncedly reduces the charge recombination in perovskite photovoltaics, leading to a record high VOC at 1.17 V. Strongly enhanced ambient and thermal stability is also demonstrated.