2D/2D vanadyl phosphate (VP) on reduced graphene oxide as a hole transporting layer for efficient organic solar cells

A solution-processable hole transporting layer (HTL) is developed using in situ formation of 2D vanadyl phosphate (VP) layered on 2D reduced graphene nanosheet (VP-rGO) for high-efficiency organic solar cells (OSCs). For the reduction of graphene oxide (GO), irradiation with electron beam was used, and for the exfoliation of VP and the blend of VP and rGO, the sonication was used. To investigate the feasibility of VP-rGO, produced by simple method for mass production, as a HTL, the surface, chemical element and electrical properties were carried out and we fabricated organic solar cells (OSCs) based on PTB7-th:PC71BM with VP-rGO as a HTL. The 2D/2D VP-rGO hybrid material specially takes advantage of both high work function of VP and good conductivity of rGO. This result leads to considerable improvement of performance in OSCs based on VP-rGO, compared with OSCs based on the PEDOT:PSS.