Wen-ren Li1,Yogesh Tingare2,Chaochin Su2,Dibyajyoti G Hosh3,Hsinhan Tsai4,Wanyi Nie4,Chien-Hsiang Lin1,Sheng-Chin Chou2,Ning-Wei Lai2,Xin-Rui Lew1
National Central University1,National Taipei University of Technology2,Indian Institute of Technology Delhi3,Los Alamos National Laboratory4
Wen-ren Li1,Yogesh Tingare2,Chaochin Su2,Dibyajyoti G Hosh3,Hsinhan Tsai4,Wanyi Nie4,Chien-Hsiang Lin1,Sheng-Chin Chou2,Ning-Wei Lai2,Xin-Rui Lew1
National Central University1,National Taipei University of Technology2,Indian Institute of Technology Delhi3,Los Alamos National Laboratory4
Increasing energy demands and concerns over global warming have led to a focus on the development of solar energy technologies. Perovskite solar cells (PSCs) have emerged as one of the most promising photovoltaics and are being investigated extensively. In inverted PSCs, hole transport materials (HTMs) assist directional charge transfer and electron blocking and also play an critical role in forming large-grained perovskites which enhance cell performance. In this work, we demonstrate a strategy for increasing the power conversion efficiency (PCE) of the device by ionizing HTMs, which introduces hydrophilicity into the HTM, improved interfacial properties, and excellent surface topographies. A comparative study of different ionizing counter anions showed that ionization also affects the absorption and emission properties, energy levels, and hole mobility of HTMs. Perovskite morphology significantly impacts PSC performance, and the anion groups like sulfoxide, SCN<sup>-</sup>, and iodide contribute effectively to the film formation and defect passivation of perovskites. Ionic dopant-free HTM with iodide entity was found to efficiently passivate the dominant surface halogen vacancy due to its smaller size, lowering the density of charge-trapping defect states and achieving a hysteresis-free power conversion efficiency of 20.46%, which was 1.71% higher than that of the non-ionic HTM. Detailed research and analysis using atomistic modeling were also investigated, providing valuable insights into the correlation between anion size and perovskite passivation and efficiency. Durability is an important aspect in PSCs and can be assisted by a suitable HTM. As result, the devices based on HTM with iodide and non-ionic HTM retained 97% and 89%, respectively, of their original PCE for 500 hours, but the device fabricated with PEDOT: PSS retained about 81% of its PCE for the same time. This study provides a technologically relevant solar cell demonstration with a mechanistic understanding of the interfacial material design. Studying other charged molecules with varying properties and sizes as counterions to develop high-performing PSCs will also be reported in the meeting.