Through Ring-Opening Reactions To Weaken the Hygroscopicity of PEDOT:PSS Films with Improved Stability of Silicon Hybrid Solar Cells

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), possessing excellent film-forming properties and high electric conductivity, is widely used in optoelectronic devices. However, the hygroscopicity of PSS results in progressive degradation of device performance during storage. Here, 4- tert -butylphenyl glycidyl ether was introduced as a reactive modifier into the PEDOT:PSS system to weaken the hygroscopicity of the PEDOT:PSS film. The 13 C NMR spectra confirmed the ring-opening reactions initiated by nucleophilic attack from the sulfonic acid groups in PSS. This reaction formed the new C–O bond between the carbon atom of the epoxy group and the oxygen atom of the sulfonic acid groups in PSS, successfully locking the hygroscopic sulfonic acid groups, thereby effectively weakening the hygroscopicity of the PEDOT:PSS film. Furthermore, the silicon hybrid solar cells were fabricated with modified PEDOT:PSS. It was found that, after 500 h of ambient air storage, the device retained 77% of the initial power conversion efficiency (PCE) of 12.31% compared to only 27% retention with the original PEDOT:PSS. This strategy provides a reference for developing stable and cost-effective optoelectronic devices utilizing PEDOT:PSS.