Modified PEDOT Layer Makes a 1.52 V Voc for Perovskite/PCBM Solar Cells

The work functions for charge transport layers in perovskite solar cells affect device performance significantly. In this work, the regular poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) is modified by adding a polymer electrolyte PSS‐Na to improve its HTL function in perovskite solar cells. The modified PEDOT:PSS films (called m‐PEDOT:PSS) possess higher work function than the regular one. Its energy level matches the valence band of perovskite very well, leading to enhanced V oc and PCE (power conversion efficiency). When CH 3 NH 3 PbI 3 is used as the light absorber, the cell with PEDOT:PSS HTL gives a V oc of 0.96 V and a PCE of 12.35%, while the cell with m‐PEDOT:PSS layer gives a V oc of 1.11 V and a PCE of 15.56%. Enhanced V oc and PCE are also achieved when CH 3 NH 3 PbI 2 Br or CH 3 NH 3 PbBr 3 is used as the light absorber. The m‐PEDOT:PSS/CH 3 NH 3 PbBr 3 /PC 61 BM solar cells demonstrate an outstanding V oc of 1.52 V.