Solution-processable fullerene derivatives for organic photovoltaics and n-type thin-film transistors

Two solution-processable fullerene derivatives (C60TH-Hx and C60TH-Hx-a) were successfully synthesized for organic photovoltaics and n-type thin-film transistors. The best power conversion efficiency (PCE) was observed in a layered structure of P3HT:C60TH-Hx (PCE = 2.44%), which slightly exceeded that of P3HT:PCBM (PCE = 2.39%). We found a very low PCE for P3HT:C60TH-Hx-a (∼0.14%) due to the poor solubility of C60TH-Hx-a. In addition, n-type thin-film transistors were fabricated by solution-processing techniques. The measured values of electron mobility in the devices for PCBM, C60TH-Hx, and C60TH-Hx-a were 5.8 × 10−3, 2.5 × 10−2, and 8.5 × 10−4 cm2 V−1 s−1, respectively.

► Two solution-processable fullerene derivatives with a hexyl thiophene group were prepared. ► One of new C60 derivatives, C60TH-Hx, which is blended with P3HT exhibited better solar cell efficiency compared with PCBM-P3HT blend. ► The thin film transistor fabricated by spin casting using C60Th-Hx showed a higher mobility than that of PCBM. ► This indicates that suitable modification of the C60 can provide an opportunity to find alternatives of PCBM.