Indene-C(60) 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.