Effects of carbon dots on ZnO nanoparticle-based dye-sensitized solar cells

ZnO nanoparticles have been assessed the effects of added carbon dots (Cdots) on the performance of photovoltaic devices: ZnO(100) and ZnO(20) with particle sizes of 94 and 20 nm, respectively, were hybridized with Cdots and characterized by current-voltage measurements under the illumination condition. The photovoltaic conversion of dye-sensitized solar cells (DSSCs) was effective for ZnO(20) superior to Zn (100) and for the incorporation of 10 wt% Cdots in the hybrid nanostructures. Moreover, when the mole ratio (ethylenediamine: citric acid) between raw materials of Cdots was 2: 1, the conversion efficiency was highest (5.9%), and this value was 7 times higher than that of ZnO(20) DSSC without Cdots. Electrochemical impedance spectroscopy also showed that the charge transfer resistance property was lowest for Cdots(2: 1)-hybridized ZnO(20) DSSC. It can be thus concluded that the performance of ZnO-based DSSCs is improved by the size-minimization of ZnO and the addition of adequate amount of Cdots. The effect of carbon dots was discussed based on electron transfer between ZnO and Cdots under the illumination. (c) 2019 Elsevier Ltd. All rights reserved.