Long-term stability of Si-organic hybrid solar cells with a thermally tunable graphene oxide platform

We demonstrated that a reduced graphene oxide (rGO) layer inserted between a poly(3,4-etylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) and Si interface improves the stability of Si-organic hybrid solar cells. Thermal reduction of a graphene oxide layer at different temperatures results in a change of water contact angle that is designed to eliminate the surface oxidation of the Si substrate. Higher temperatures generate a smaller aromatic sp(2) domain size that changes the GO surface from hydrophilic to hydrophobic. Additionally, two-dimensional GO layers can serve as a barrier for both liquid and vapor permeation. Consequently, the PEDOT:PSS/Si device with a rGO passivation layer shows a significantly enhanced air-stability from the J-V characteristic under illumination during a one-month storage period. The application of rGO is a promising technique to extend the stability of Si-organic solar cells without an encapsulation process.