Inverted organic solar cells employing RGO/TiOx composite films as electron transport layers

Reduced graphene oxide (RGO)/titanium oxide (TiOx) (RGO/TiOx) composite films are successfully prepared by a sol-gel method. Inverted organic solar cells incorporating RGO/TiOx composite as electron transport layer and MoO3 as hole transport layer were fabricated. A short-circuit current of 9.85 mA/cm2 and power conversion efficiency of 3.82% are achieved by using the RGO/TiOx composite films with 0.083 mg/mL of RGO in TiO2 colloidal solution as electron transport layers for the inverted solar cells based on P3HT and PCBM, which are increased by 14.8% and 26.1% compared with the reference device without RGO, respectively. Impedance measurements revealed that the significantly enhanced efficiency was attributed to the RGO/TiOx composite films with efficient electron transport.