oCVD PEDOT-Cl Thin Film Fabricated by SbCl₅ Oxidant as the Hole Transport Layer to Enhance the Perovskite Solar Cell Device Stability

Perovskite solar cells (PSCs) exhibit remarkable power conversion efficiency (PCE) but face limitations due to poor stability, restricting their practical applications. The commonly used hole transport layer, poly(3,4-ethylene dioxythiophene):polystyrenesulfonate (PEDOT:PSS), suffers from inherent acidity that compromises PSCs device stability through detrimental interactions with the counter electrode and perovskite layer. This study explores the use of oxidative chemical vapor deposition (oCVD) with antimony pentachloride (SbCl 5 ) as a liquid oxidant to fabricate stable, ultrathin, and highly conformal PEDOT thin films, presenting a promising alternative for the hole transport layer in PSCs. The oCVD PEDOT-Cl thin films, grown using liquid SbCl 5 oxidant, demonstrate excellent optoelectronic properties, precise control over nanostructure, stability, and integration capabilities, making them a robust and efficient choice as a hole transport layer. Integration of oCVD PEDOT-Cl thin films as the hole transport layer in PSCs yields a remarkable PCE of 20.74%, surpassing the PCE of 16.53% obtained by spin-coated PEDOT:PSS thin films treated with the dimethyl sulfoxide (DMSO) polar solvent. Furthermore, PSCs incorporating oCVD PEDOT-Cl thin films demonstrate a notable 2.5× enhancement in stability compared to PEDOT:PSS-DMSO counterparts. Utilizing as-deposited oCVD PEDOT-Cl thin films fabricated using SbCl 5 oxidant with highly conformal characteristics introduces opportunities for enhancing light absorption by the photoactive layer through artificially textured surfaces. This advancement opens up possibilities for the development of PSCs with high performance and enhanced stability.