Highly Efficient Bifacial Semitransparent Perovskite Solar Cells Based on Molecular Doping of CuSCN Hole Transport Layer

Coper thiocyanate (CuSCN) is generally considered as a very hopeful inorganic hole transport material (HTM) in semitransparent perovskite solar cells (ST-PSCs) because of its low parasitic absorption, high inherent stability, and low cost. However, the poor electrical conductivity and low work function of CuSCN lead to the insufficient hole extraction and large open-circuit voltage loss. Here, 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) is employed to improve conductivity of CuSCN and band alignment at the CuSCN/perovskite (PVK) interface. As a result, the average power conversion efficiency (PCE) of PSCs is boosted by ≈ 11%. In addition, benefiting from the superior transparency of p-type CuSCN HTMs, the prepared bifacial semitransparent n–i–p planar PSCs demonstrate a maximum efficiency of 14.8% and 12.5% by the illumination from the front side and back side, respectively. We believe that this developed CuSCN-based ST-PSCs will promote practical applications in building integrated photovoltaics and tandem solar cells.