Design of PEDOT Derivative Films with Reduced Hygroscopicity by Dual-Sulfonated Polymer for Stable Si Hybrid Solar Cells

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is commonly used in optoelectronic devices, but its intrinsic hygroscopicity impairs device stability. Here, a PEDOT derivative film with surface hydrophobicity and reduced internal hygroscopicity was designed through dual-sulfonated polymer, successfully improving the stability of Si hybrid solar cells. The surface hydrophobicity of the film was associated with EG-induced enhanced exposure of the fluorocarbon chains of Nafion, achieving a water contact angle of 108.1°. Furthermore, after poly(propylene glycol) diglycidyl ether (PPGDGE) was introduced to construct a cross-linked network, the internal hygroscopicity of the film was further reduced. As a result, the device retained 78% of its initial power conversion efficiency (PCE) after 432 h of storage in air, compared with only 57% for PEDOT:PSS. This provides a feasible design concept for mitigating the adverse impact of PEDOT:PSS on device stability and also indicates the potential of this film to construct other stable optoelectronic devices.