Abstract
This work presents the studies of bulk heterojunction solar cells based on CIGS NCs embedded in poly(3-hexylthiophene) matrices. In order to improve the power conversion efficiency of the photovoltaic devices, the blend ratio、solvent effects、devices annealing effects、surface modification and the incorporation of graphene have been investigated. The optimal blend ratio of devices we achieved was WP3HT/WCIGS NCs=1/3；In the studies of different solvents on the nanomorphology of active layer, 1,2-dichlorobenzene utilized as solvent exhibited the best PCE；From the devices annealing, we found out that the devices annealed at 100oC for 4 min shows enhanced PCE；In order to improve the dissociation of excitons and facilitate the charges transporting, we substitute the pyridine from oleyamine as capping ligand of CIGS NCs. In the end, the graphene nanosheets are incorporated into hole transporting layer to further facilitate the charge transporting on the interfaces. In summary, the best performance devices was fabricated from a blend ratio of 1 to 3 by weight in P3HT to CIGS NCs, dichlorobenzene as solvent, pyridine as surfactant, graphene incorporated into hole transporting layer. The device exhibits PCE ~0.019% under AM 1.5 simulated solar illumination (100mW/cm2).