Organic–inorganic halide perovskites have attracted worldwide attention due to their impressive electrical and optical properties leading to remarkable performance in solar cells and light emitting devices. In the past few years, intensive investigations leading to certified power conversion efficiencies (PCEs) exceeding 20% were carried out. Hole-transporting materials (HTMs) are an essential building block of perovskite solar cells (PSCs) architectures. Currently, 2,2′,7,7′-tetrakis-(N,N-di-p-methoxyphenyl-amine)-9,9′-spirobifluorene, better known as spiro-OMeTAD, is the most widely-used HTM to obtain high-efficiency devices. However, it is a tremendously expensive material with mediocre hole carrier mobility. In this respect, it is important to develop other alternative HTMs for further improving PCE.

     In this presentation, we devoted our efforts to developing new HTMs for PSCs based on cyclopenta[2,1-b;3,4-b’]dithiophene cores. The relationship between the molecular structure of the novel HTMs and performance of PSCs was investigated, leading to a fundamental understanding of the requirements of the HTMs and further improvement of the photovoltaic performance.