Delafossite CuCoO₂/ZnO derived from ZIF-8 heterojunctions as efficient photoelectrodes for dye-sensitized solar cells

Abstract

To achieve high-performance dye-sensitized solar cells (DSSCs), it is essential to establish new and effective photoelectrode materials. Herein, we report the successful synthesis of heterojunctions including Cu-based delafossite oxide CuCoO₂ and ZnO derived from zeolitic imidazolate framework-8 (ZIF-8). The layered polyhedral nanocrystals of CuCoO₂ produced through a feasible low temperature hydrothermal process and the faceted nanocrystals of ZnO were achieved by heat treatment of ZIF-8. The composite heterostructures were applied as photoelectrodes in DSSCs assembled using dye N719 and a Pt counter electrode. The physicochemical characteristics (XRD, FESEM, EDAX, mapping, BET, DRS), dye loading, and photovoltaic properties (<i>J</i>-<i>V</i>, EIS, IPCE) of the fabricated materials were studied and fully discussed. Results revealed that addition of CuCoO₂ to ZnO significantly improved the <i>V</i>_oc, <i>J</i>_sc, PCE, FF, and IPCE. Among all cells, CuCoO₂/ZnO (0.1 : 1) showed the best performance (PCE = 6.27%, <i>J</i>_sc = 14.56 mA cm^-2, <i>V</i>_oc = 687.84 mV, FF = 62.67%, IPCE = 45.22%) and acted as a promising photoanode in DSSCs.