PEDOT:PSS-Metal Oxide Composite Electrode with Regulated Wettability and Work Function for High-Performance Inverted Perovskite Solar Cells

Poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) can be roll-to-roll deposited on the substrate facilely in the electronics, but its acidity and mismatched energy level limit the performance and stability. Herein, different metal salts are incorporated into PEDOT:PSS solution to prepare PEDOT:PSS-A(x)O(y)(metal oxide) composite hole transport layer and it is found that the performance of inverted perovskite solar cells (PSCs) can be greatly enhanced. PSC using PEDOT:PSS-MoO(x)has achieved much higher power conversion efficiency (PCE) (19.64%) than that of pristine PEDOT:PSS (12.19%). Two key factors are important for the performance enhancement. First, the increased surface free energy of PEDOT:PSS-A(x)O(y)is beneficial for the formation of large crystal size and pinhole-free film, leading to reduced nonradiative recombination. Second, the work function of PEDOT:PSS can be tuned to match the energy level of photoactive layer with small amount incorporation, which greatly enhances the photovoltage by a factor of 1.1. Besides, the devices based on PEDOT:PSS-A(x)O(y)exhibit improved long-term stability. Unencapsulated PSCs with PEDOT:PSS-MoO(x)retain over 90% and 80% of their initial PCEs in N(2)for 45 d and in ambient air for 20 d, respectively. The modified PEDOT:PSS solutions overcome the intrinsic imperfection and can be potentially employed for large-scale production in the electronic devices.