Efficient flexible organic solar cells with room temperature sputtered and highly conductive NiO as hole-transporting layer

We report efficient bulk-heterojunction [regioregular of poly(3-hexylthiophene) (P3HT) : (6,6)-phenyl C-61 butyric acid methyl ester(PCBM)] solar cells with a highly transparent and electrical conductive NiO film as hole-transporting layer (HTL). The highest power conversion efficiency (PCE) of 3.26% of FTO/NiO/P3HT : PCBM/Al solar cells on glass was achieved through NiO thin film sputtering temperature, film thickness optimization and it was found that NiO with 10 nm and sputtered at room temperature shows the best photovoltaic properties. Under the optimized condition, PCE of 2.5% on flexible substrate was achieved with highly electrical conductive and room temperature sputtered NiO as HTL.