Fullerene–non-fullerene hybrid acceptors for enhanced light absorption and electrical properties in organic solar cells

Abstract

Two fullerene–non-fullerene hybrid acceptors, IDTIC-PC61BM (IP) and PC61BM-IDTIC-PC61BM (PIP), are synthesized by combining a non-fullerene acceptor, 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2′,3′-d’]-s-indaceno[1,2-b:5,6-b’]dithiophene (IDTIC), and a fullerene derivative, phenyl-C61-butyric acid methyl ester (PC61BM). To evaluate the potential of these hybrid acceptors, we fabricate organic solar cells (OSCs) based on the four different acceptors (i.e. IP, PIP, IDTIC, and PC61BM) and the same polymer donor (PBDB-T). In IP and PIP, the IDTIC moiety compensates for the poor light absorption of PC61BM in the visible wavelength region, improving the short-circuit current density (JSC) of the hybrid acceptor-based OSCs (11.9 → 13.1 mA cm−2). Meanwhile, the charge transport and recombination properties of the PBDB-T:IDTIC devices improve significantly after the substitution of IDTIC with IP or PIP, leading to a significant increase in the fill factor (0.54 → 0.68) as well as JSC (11.8 → 13.1 mA cm−2) of the devices. Therefore, owing to the synergistic effect of the broad light absorption of IDTIC and efficient electron transport of PC61BM, the hybrid acceptor-based OSCs show significantly higher power conversion efficiencies of 8.81% (PBDB-T:PIP) and 8.17% (PBDB-T:IP) than the PBDB-T:PC61BM (7.62%) and PBDB-T:IDTIC (5.98%) OSCs. The results demonstrate the effectiveness of the hybrid acceptor design in overcoming the shortcomings of individual acceptors and improving their photovoltaic performance.