Graphene quantum dots doping SnO2 for improving carrier transport of perovskite solar cells

Abstract

SnO2 is recognized as an excellent electron transport layer. However, it does not possess the optimal morphology required by perovskite photovoltaic devices, and the conduction band of SnO2 cannot match well with perovskite conduction bands. In the present study, we introduced graphene quantum dots (GQDs) into SnO2. The results show that the introduction of graphene quantum dots effectively improved the morphology of the SnO2 film, reduced the roughness of the surface, and increased the ohmic contact between the SnO2 and perovskite layer. In addition, the conductivity of the SnO2 film was improved, thereby facilitating the transfer of electrons. The optimized SnO2: GQDs layer reduced the density of defect state, suppressed the pinholes appearance to a certain extent, and facilitated the extraction of electrons, thereby ultimately improving the FF, and increasing the efficiency of the perovskite photovoltaic device.