Derived from double-walled carbon nanotubes, graphene quantum dots (GQDs) with a uniform size distribution were prepared through solution chemistry. The GQDs in chlorobenzene exhibited bright blue emission upon UV excitation. The introduction of the GQDs into a bulk heterojunction polymer solar cell based on poly(3-hexylthiophene):(6,6)-phenyl-C61 butyric acid methyl ester (P3HT:PCBM) resulted in a significant enhancement of the power conversion efficiency (PCE). The efficiency was further improved by adjusting the PCBM content in the active layer, reaching a maximum PCE of 5.24%. This ternary system based on blended P3HT:PCBM:GQDs represents a new method to enhance the efficiency of polymer solar cells.

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