Recent Advances in Organic Hole Transporting Materials for Perovskite Solar Cells

Perovskite solar cells (PSCs) with advantages of exceptional photovoltaic performance and facile solution-processed fabrication have shown great potential in future scalable application. After about a decade of rapid development, this new PSCs technology demonstrates over 25% efficiency, a comparable performance with traditional silicon solar cells. Further, the development of PSCs in the direction of scalable production still highly relies on designing innovative materials with low cost and high efficiency. Recently, a great number of functional organic molecules as hole transport materials (HTMs) have been designed, synthesized, and studied in PSCs, including molecules with planar structure, 3D geometry, or different core units. Discovering the correlation between their chemical structures and physicochemical properties plays a fundamental role in supervising future molecular design and synthesis. Herein, recent advances in organic molecular HTMs with various structures in typical and reverse PSCs device configuration are summarized, including doped and doping-free materials. By evaluating the structural modification and analyzing their effects on photovoltaic performance, the goal is to generate universal strategies for preparing low-cost and efficient HTMs, paving the way for future scalable application of PSCs.