Improved performance of inverted planar perovskite solar cells with F4-TCNQ doped PEDOT:PSS hole transport layers
Rational hole transport layer (HTL) material design is regarded as one of the most important approaches to improve the efficiency and stability of perovskite solar cells (PSCs). Herein, we investigate the effect of a widely spread p-type dopant 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ) on the optical and electrical properties of conventional poly(3,4-ethylenedioxythiophene):poly-(styrene sulfonate) (PEDOT:PSS) HTLs, as well as the photovoltaic performance of the corresponding perovskite solar cells. Doping F4-TCNQ at a low concentration can efficiently adjust the electrical properties of the PEDOT:PSS film and lower the highest occupied molecular orbital (HOMO) level. As a result, the enhanced electrical conductivity and energetically favorable energy level alignment of the doped film allow efficient carrier transport from the perovskite absorber layer to the HTL. Finally, the PSCs with the F4-TCNQ doped HTL exhibited simultaneously increased short-circuit current (Jsc), open circuit voltage (Voc) and fill factor (FF). The highest power conversion efficiency (PCE) was notably improved from 13.30% (undoped) to 17.22% (0.30 wt% of F4-TCNQ doping), suggesting that the F4-TCNQ doped PEDOT:PSS film is an efficient HTL to achieve high performance perovskite solar cells.