The role of surfactant-treated graphene oxide in polymer solar cells: Mobility study

In our previous work, the device performance of polymer solar cells (PSCs) was enhanced by blending surfactant-treated graphene oxide (GO) nanocomposites [didodecyldimethyla-mmonium bromide (DDAB):GO] as the active layer. However, its underlain mechanism is not clearly reported. In this work, therefore we measured the charge carriers mobility of the active layers before and after blending GO:DDAB nanocomposites to reveal the role of GO:DDAB in PSCs, and found that GO:DDAB can form three-dimensional network for charge carriers transport, meanwhile ‘traps’ for electrons can be introduced by GO:DDAB and formed in the bulk and/or at active-layer/electrode interfaces, compromising the electron mobility. Meanwhile, the hole mobility was improved due to the enhanced crystallinity of the composite films after blending GO:DDAB into P3HT:PCBM. Therefore, the transport balance between electrons and holes is enhanced and thus the device performance is improved.