Indene-C60 Bisadduct: A New Acceptor for High-Performance Polymer Solar Cells

Polymer solar cells (PSCs) are commonly composed of a blend film of a conjugated polymer donor and a soluble C-60 derivative acceptor sandwiched between an ITO anode and a low-workfunction metal cathode. Poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C-61-butyric acid methyl ester (PCBM) are the most widely used donor and acceptor materials, respectively. However, the low LUMO energy level of PCBM limits the open circuit voltage (V-oc) of the P3HT-based PSCs to ca. 0.6 V. Here we synthesized a new soluble C-60 derivative, indene-C-60 bisadduct (ICBA), with a LUMO energy level 0. 17 eV higher than that of PCBM. The PSC based on P3HT with ICBA as acceptor shows a higher V-oc of 0.84 V and higher power conversion efficiency (PCE) of 5.44% under the illumination of AM1.5, 100 mW/cm(2), while the PSC based on P3HT/PCBM displays a V-oc of 0.58 V and PCE of 3.88% under the same experimental conditions. The results indicate that ICBA is an alternative high-performance acceptor and could be widely used in high-performance PSCs.