Yang, FengjiuTockhorn, PhilippMusiienko, ArtemLang, FelixMenzel, DorotheeMacqueen, RowanKöhnen, EikeXu, KeMariotti, SilviaMantione, DanieleMerten, LenaHinderhofer, AlexanderLi, BorWargulski, Dan R.Harvey, Steven P.Zhang, JiahuanScheler, FlorianBerwig, SebastianRoß, MarcelThiesbrummel, JarlaAl‐Ashouri, AmranBrinkmann, Kai O.Riedl, ThomasSchreiber, FrankAbou‐Ras, DanielSnaith, HenryNeher, DieterKorte, LarsStolterfoht, MartinAlbrecht, Steve2024-04-262024-04-262023-12-060935-9648https://depositonce.tu-berlin.de/handle/11303/21538https://doi.org/10.14279/depositonce-20338All-perovskite tandem solar cells show great potential to enable the highest performance at reasonable costs for a viable market entry in the near future. In particular, wide-bandgap (WBG) perovskites with higher open-circuit voltage (VOC) are essential to further improve the tandem solar cells’ performance. Here, a new 1.8 eV bandgap triple-halide perovskite composition in conjunction with a piperazinium iodide (PI) surface treatment is developed. With structural analysis, it is found that the PI modifies the surface through a reduction of excess lead iodide in the perovskite and additionally penetrates the bulk. Constant light-induced magneto-transport measurements are applied to separately resolve charge carrier properties of electrons and holes. These measurements reveal a reduced deep trap state density, and improved steady-state carrier lifetime (factor 2.6) and diffusion lengths (factor 1.6). As a result, WBG PSCs achieve 1.36 V VOC, reaching 90% of the radiative limit. Combined with a 1.26 eV narrow bandgap (NBG) perovskite with a rubidium iodide additive, this enables a tandem cell with a certified scan efficiency of 27.5%.en600 Technik, Medizin, angewandte Wissenschaften::620 Ingenieurwissenschaften::621 Angewandte Physikall‐perovskite tandem solar cellspiperazinium iodiderecombination lossestriple‐halide wide‐bandgap perovskiteArticle2024-04-151521-4095