Effect of solution-processed niO thin film as a hole transport layer in poly(3-hexylthiophene): [6,6]-phenyl C61-butyric acid methyl ester bulk heterojunction solar cells

In this study, solution-processed nickel oxide (NiO) thin film was investigated as a hole transport layer on anode to improve the performance of bulk heterojunction solar cell based on poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C61-butyric acid methyl ester (PCBM). We fabricated NiO thin film without any vacuum-related process. Characterization of the NiO film under this study shows that it has maximum transmittance of 93.22% and bandgap of 3.84 eV which are proper for solar cell. Insertion of the NiO layer affords to realize enhanced power conversion efficiency of 1.97% and fill factor of 52.11% showing improvement over existing cells. In addition, NiO suggests one solution of minimizing conventional problems of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) such as interfacial power losses, corrosion of indium tin oxide layer, and degradation of the devices. The value of such hole transporting and electron blocking properties is clearly demonstrated and could be applicable to other organic photovoltaics.