High-performance polymer solar cells with moderately reduced graphene oxide as an efficient hole transporting layer

As an alternative to the poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) hole transporting layer (HTL) in polymer solar cells (PSCs), moderately reduced graphene oxide (GO) films fabricated by simple and fast thermal treatment of solution processed GO were investigated. PSC with thermally treated GO at 250 °C exhibited best performance with a power conversion efficiency (PCE) of 3.98%, compared to the PSC containing conventional PEDOT:PSS HTL with a PCE of 3.85%. Furthermore, the PSC with thermally treated GO showed superior stability compared to the PSC with conventional PEDOT:PSS HTL under the atmosphere condition without any encapsulation process. Our demonstration suggests that moderately reduced GO by simple thermal treatment could be promising HTL replacing PEDOT:PSS in PSCs as well as other organic electronics.