Halide Segregation versus Interfacial Recombination in Bromide-Rich Wide-Gap Perovskite Solar Cells

作者：Francisco Peña‐Camargo, Pietro Caprioglio, Fengshuo Zu, Emilio Gutierrez‐Partida, Christian M. Wolff, Kai Oliver Brinkmann, Steve Albrecht, Thomas Riedl, Norbert Koch, Dieter Neher, Martin Stolterfoht · 发表于：ACS Energy Letters · 年份：2020 · DOI：10.1021/acsenergylett.0c01104 · 被引用次数：199 · 研究领域：Perovskite Materials and Applications、Chalcogenide Semiconductor Thin Films、Quantum Dots Synthesis And Properties

Perovskites offer exciting opportunities to realize efficient multijunction photovoltaic devices. This requires high- V OC and often Br-rich perovskites, which currently suffer from halide segregation. Here, we study triple-cation perovskite cells over a wide bandgap range (∼1.5–1.9 eV). While all wide-gap cells (≥1.69 eV) experience rapid phase segregation under illumination, the electroluminescence spectra are less affected by this process. The measurements reveal a low radiative efficiency of the mixed halide phase which explains the V OC losses with increasing Br content. Photoluminescence measurements on nonsegregated partial cell stacks demonstrate that both transport layers (PTAA and C 60 ) induce significant nonradiative interfacial recombination, especially in Br-rich (>30%) samples. Therefore, the presence of the segregated iodide-rich domains is not directly responsible for the V OC losses. Moreover, LiF can only improve the V OC of cells that are primarily limited by the n -interface (≤1.75 eV), resulting in 20% efficient 1.7 eV bandgap cells. However, a simultaneous optimization of the p -interface is necessary to further advance larger bandgap (≥1.75 eV) pin -type cells.