Efficiency enhancement of solution-processed inverted organic solar cells with a carbon-nanotube-doped active layer

Solution-processed titanium-doped ZnO (TZO) is synthesized by the sol-gel method to be the electron-transporting layer (ETL) in an inverted organic solar cell (IOSC). Carbon nanotubes (CNTs) are doped into an active layer of poly(3-hexylthiophene):[6,6]-phenyl C 61 butyric acid methyl ester (P3HT:PCBM). The addition of CNTs in the P3HT:PCBM composite increases the conjugation length of P3HT: PCBM: CNTs, which simultaneously enhances the capacity of the composite to absorb solar energy radiation. Vanadium oxide (V2O5) was spin-coated onto the active layer to be a hole-transporting layer (HTL). The power conversion efficiency (PCE) results indicate that the V2O5 nanobelt structure possesses better phase separation and provides a more efficient surface area for the P3HT:PCBM:CNT active layer to increase photocurrent. The optimized IOSCs exhibited an open circuit voltage (V-oc), a short-circuit current density (J(sc)), a fill factor (FF), and a PCE of 0.55V, 6.50mA/cm(2), 58.34%, and 2.20%, respectively, under simulated AM1.5G illumination of 100mW/cm(2). (C) 2016 The Japan Society of Applied Physics