High-Performance Hybrid Photovoltaics with Efficient Interfacial Contacts between Vertically Aligned ZnO Nanowire Arrays and Organic Semiconductors

Abstract

Hybrid photovoltaics (HPVs) incorporating both organic and inorganic semiconducting materials have attracted much attention as next-generation photovoltaics because of their advantage of combining both materials. The hybridization of ZnO nanowires (NWs) and organic semiconductors is expected to be a suitable approach to overcome the limited exciton diffusion length and low electron mobility associated with current organic photovoltaics. The use of ZnO NWs allows researchers to tune nanoscale dimensions more precisely and to achieve rod-to-rod spacing below 10 nm. However, the perfect incorporation of organic semiconductors into densely packed ZnO NW arrays has yet to be achieved. In this study, we report the fabrication of ZnO NW arrays and various organic heterojunction-based HPVs using the feasible and effective vacuum-assisted double coating (VADC) method, achieving full coverage of the organic semiconductors on the compact ZnO NW arrays. The newly proposed VADC method ensures perfect infiltration and full coverage of the organic semiconductors on the densely packed NW arrays. Compared with the conventional single spin-coating process, the use of the VADC method led to 11 and 14% increases in the power conversion efficiency of P3HT:PCBM- and PBDTTT-C-T:PC71BM-based HPVs, respectively. Our studies provide a feasible method for the fabrication of efficient HPVs.