Boost Organic‐Silicon Hybrid Solar Cell Performances with a Facile and Cost‐Effective Sub‐3 nm Interface Control Method

A facile and cost‐effective approach based on oxygen‐plasma treatment is developed for silicon‐organic hybrid solar cells. By precisely forming a sub‐3 nm SiO x layer at the silicon‐poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) interface with a 10 s oxygen‐plasma treatment, the power conversion efficiency is boosted from 0.02% to 8.18%, 409‐fold increase compared to solar cells with untreated silicon. Utilizing X‐ray photoelectron spectroscopy, Kelvin probe force microscopy, and density‐functional theory, the device physics and mechanisms are revealed from an atomic‐level perspective. The control of interface by oxygen‐plasma treatment reduces the surface work function of Si and introduces an electron barrier, facilitating the transfer of hole carriers from Si to organic materials while effectively blocking electron transmission. This mechanism proves to be highly beneficial in mitigating carrier recombination and promoting the separation of electrons and holes. This approach can be applied to interface optimization for high‐performance photovoltaic and other optoelectronic devices.