Doping PEDOT:PSS with cesium chloride for enhancing the performance of perovskite solar cells

Abstract

Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is the most commonly used hole transport layer (HTL) material in perovskite solar cells (PSCs) due to its high visible light transmittance, excellent solution processability, and wettability suitable for top perovskite formation. The presence of surface defects in PEDOT:PSS films decreases the photoelectric conversion efficiency (PCE) and long-term stability of PSCs. These defects lead to the formation of pores in the growth of perovskite films on PEDOT:PSS, impeding the extraction and transfer of effective charges. Therefore, in this article, cesium chloride is doped into PEDOT:PSS to enhance its surface morphology, reduce surface roughness, improve the quality of sulfide thin films, promote charge transfer ability between interfaces, enhance conductivity, reduce non radiative recombination of the device, and improve the photovoltaic performance of the device. The open circuit voltage (V_OC) increased from 1.00 V to 1.02 V, the short-circuit current (J_SC) increased from 21.04 mA cm⁻² to 21.72 mA cm⁻², the fill factor (FF) increased from 77.90% to 82.04%, and the PCE of MAPbI_3−xCl_x PSCs increased from 16.39% to 18.18%. Specifically, when using cesium chloride-doped PEDOT:PSS as the HTL, the PCE of the Sn-Pb PSCs increased from 19.49% to 21.44%.