Preparation of highly conductive PEDOT:PSS hole transport layer by simple treatment with ethanol for Sn–Pb perovskite solar cells

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), an ordinary hole transport layer (HTL), has inherent shortcomings that restrict its use in Sn–Pb perovskite solar cells (PSCs). In this study, PEDOT:PSS was mixed with ethanol using a simple solution method, resulting in enhanced conductivity and an optimized work function. By varying the concentration of ethanol doping, the insulated PSS shell surrounding the PEDOT:PSS was stripped, and the conductivity of PEDOT:PSS was increased from 4.50 × 10−4 S cm−1 to 7.00 × 10−4 S cm−1. The work function was lowered by 0.23 eV to −5.30 eV, bringing it closer to the energy level of Sn–Pb perovskite. Ethanol-doped PEDOT:PSS was utilized as the HTL in Sn–Pb PSCs based on FA0.5MA0.5Sn0.5Pb0.5I3, resulting in 18.10% photoelectric conversion efficiency with negligible hysteresis, and more than 40% performance improvement compared to the undoped devices. Furthermore, the treatment of ethanol could enhance the stability of the devices. The doped device was placed in a glove box for one month, and its efficiency remained above 90% of the maximum value. Thus, ethanol doping in PEDOT:PSS should provide a promising strategy for developing HTLs in efficient Sn–Pb PSCs.