Hybrid organic solar cells using both ZnO and PCBM as electron acceptor materials

Highlights: • Organic hybrid photovoltaic devices with ZnO were fabricated. • Varying the ratio of PCBM and ZnO optimized the devices. • Using a mixture of ZnO and PCBM made the highest efficiency. • ZnO addition increased P3HT crystallinity and reduced resistances. - Abstract: In this paper, we studied the effect of the addition of zinc oxide (ZnO) nanoparticles to the active layer of poly(3-hexylthiophene) and [6,6]-phenyl C61-butyric acid methyl ester (P3HT:PCBM) solar cells. Devices with varying ratios of ZnO and PCBM were fabricated while maintaining a fixed concentration of P3HT. This effect was investigated in different solvents, specificaly chlorobenzene (CB) and 1,2-dichlorobenzene (DCB). The addition of ZnO nanoparticles was found to significantly increase the power conversion efficiency (PCE) in the P3HT:PCBM solar cells. The mixing of ZnO in the active layer using CB as the solvent introduced a red shift in the absorption spectra and enhanced the absorption in the visible region. The incorporation of ZnO nanoparticles was also found to increase the surface roughness of the active layer. ZnO nanoparticles agglomerated as their concentration relative to PCBM increased and completely agglomerated in the absence of the fullerene derivative