TY - GEN A1 - Zia, Waqas A1 - Malekshahi Byranvand, Mahdi A1 - Rudolph, Toby A1 - Rai, Monika A1 - Kot, Małgorzata A1 - Das, Chittaranjan A1 - Kedia, Mayank A1 - Zohdi, Mohammadreza A1 - Zuo, Weiwei A1 - Yeddu, Vishal A1 - Saidaminov, Makhsud I. A1 - Flege, Jan Ingo A1 - Kirchartz, Thomas A1 - Saliba, Michael T1 - MAPbCl3 Light Absorber for Highest Voltage Perovskite Solar Cells T2 - ACS Energy Letters N2 - Perovskite solar cells (PSCs) excel in achieving high open-circuit voltages (VOC) for narrow bandgaps (∼1.6 eV) but face challenges with wide-bandgap perovskites, like methylammonium lead trichloride (MAPbCl3) with a 3.03 eV bandgap. These materials are transparent in visible absorbing ultraviolet (UV) light. However, achieving uniform film crystallization remains a hurdle. Here, we enhance MAPbCl3 crystallization by manipulating annealing atmospheres (nitrogen, air, and MACl vapor). Excess MACl vapor improves surface coverage, which is crucial for film stability. We demonstrate that the microstructure of the perovskite film, including surface morphology, grain boundaries, and interfaces, can affect the photovoltaic properties. The subsequently obtained VOC of 1.78 V is the highest recorded for single-junction PSCs to the best of our knowledge. Surprisingly, the conventional hole-transport layer spiro-OMeTAD, optimized for narrow bandgaps, sustains such high voltages. Photoluminescence measurements reveal a trap-assisted recombination peak at 1.65 eV, indicating deep traps as significant to voltage loss in MAPbCl3. KW - Perovskite solar cells KW - methylammonium lead trichloride (MAPbCl3) KW - uniform film crystallization KW - manipulation of annealing atmospheres KW - trap-assisted recombination KW - microstructure Y1 - 2024 U6 - https://doi.org/10.1021/acsenergylett.3c02777 SN - 2380-8195 VL - 9 SP - 1017 EP - 1024 ER -