Record Efficiency Stable Flexible Perovskite Solar Cell Using Effective Additive Assistant Strategy

• Published in: Advanced materials (Weinheim) 2018-08, Vol.30 (35), p.e1801418-n/a
• Main Authors: Feng, Jiangshan, Zhu, Xuejie, Yang, Zhou, Zhang, Xiaorong, Niu, Jinzhi, Wang, Ziyu, Zuo, Shengnan, Priya, Shashank, Liu, Shengzhong (Frank), Yang, Dong
• Format: Article
• Language: English
• Subjects: additive; Crystallization; Dimethyl sulfide; Efficiency; Energy conversion efficiency; flexible; Fourier transforms; Grain boundaries; Grain size; Materials science; Performance enhancement; perovskite solar cell; Perovskites; Photovoltaic cells; Reaction kinetics; Solar cells; Tolerances (mechanics)
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.201801418

Even though the power conversion efficiency (PCE) of rigid perovskite solar cells is increased to 22.7%, the PCE of flexible perovskite solar cells (F‐PSCs) is still lower. Here, a novel dimethyl sulfide (DS) additive is developed to effectively improve the performance of the F‐PSCs. Fourier transform infrared spectroscopy reveals that the DS additive reacts with Pb2+ to form a chelated intermediate, which significantly slows down the crystallization rate, leading to large grain size and good crystallinity for the resultant perovskite film. In fact, the trap density of the perovskite film prepared using the DS additive is reduced by an order of magnitude compared to the one without it, demonstrating that the additive effectively retards transformation kinetics during the thin film formation process. As a result, the PCE of the flexible devices increases to 18.40%, with good mechanical tolerance, the highest reported so far for the F‐PSCs. Meanwhile, the environmental stability of the F‐PSCs significantly enhances by 1.72 times compared to the device without the additive, likely due to the large grain size that suppresses perovskite degradation at grain boundaries. The present strategy will help guide development of high efficiency F‐PSCs for practical applications. An efficiency of flexible perovskite solar cells (F‐PSCs) is achieved of 18.40% with small area and 13.35% with large area using effective dimethyl sulfide (DS) additive; both are the highest reported for the F‐PSCs. The F‐PSCs show high efficiency and good stability due to the large grain size and good crystallinity of perovskite when DS is used.