Enhancing charge separation and photocurrent response of CuO nanocone array by constructing CuO/PC61BM hybrid bulk heterojunction

An inorganic–organic hybrid bulk heterojunction (BHJ) consisting of a CuO nanocone array (NCA)/methyl [6,6]-phenyl-C61-butyrate (PC 61 BM) was fabricated on a fluorine-doped tin oxide substrate using a hydrothermal method. Scanning electron microscopy showed that the CuO-NCA/PC 61 BM BHJ hybrid structure was well-formed and that the PC 61 BM compactly filled the interspaces between the CuO nanocones. A FTO/CuO-NCA/PC 61 BM/LiF/Ag hybrid BHJ photodiode had a favorable type-II band alignment for charge separation, and this photodiode showed a nearly 10-fold enhanced photocurrent response compared with a FTO/CuO-NCA/LiF/Ag Schottky junction photodiode. Photoelectrochemical impedance spectroscopy and transient absorption spectroscopy demonstrated that the FTO/CuO-NCA/PC 61 BM/LiF/Ag BHJ device had better photogenerated charge transfer properties and a longer carrier lifetime compared with the FTO/CuO-NCA/LiF/Ag device.