Small molecule dye rubrene doped organic bulk heterojunction solar cells

•Small molecule dye of rubrene was doped into P3HT:PCBM heterojunction solar cells.•Rubrene increased the absorption and charge separation of active layers.•Short current circuit and power conversion efficiency of solar cells were enhanced.•Photocurrent of solar cells was simulated using Onsager–Braun theory.•Rubrene doping improved the charge transfer generation and dissociation.

Poly(3-hexylthiphene) (P3HT):[6,6]-phenyl C60-butyric acid methyl ester (PCBM) bulk heterojunction solar cells doped with a small molecule dye of rubrene were fabricated. The effect of different doping concentration on the performance of solar cells was investigated. The results showed that by doping 3.5 wt% rubrene, the short circuit current and the power conversion efficiency (PCE) of the cell were improved by 23.1% and 23.4%, respectively. The increased light absorption and effective charge separation of blend films contributed to the enhancement of PCE in doping devices. Moreover, by simulating the photocurrent of solar cells using Onsager–Braun theory, it was found that doping rubrene was responsible for the enhancement of charge transfer generation and dissociation, thereby improving the performance of P3HT:PCBM solar cells.