High‐Efficiency Dye‐Sensitized Solar Cells Based on a ZnO Nanorod/ Nanosheet Hierarchical Structure

Abstract

An aqueous solution of Zn(NO3)2⋅6 H2O‐C6H2N4‐PEI and Zn(NO3)2⋅6 H2O‐CO(NH2)2 is used as the raw materials to fabricate hierarchically structured films of ZnO nanorods/nanosheets (ZnO NRs/NSs) via a two‐step hydrothermal synthesis. The films of ZnO NRs/NSs are then applied as photoanodes for application in dye‐sensitized solar cells (DSSCs). The current density–voltage curves and the incident monochromatic photon‐to‐electron conversion efficiency of DSSCs are measured. Using electrochemical impedance spectroscopy, intensity modulated photovoltage spectroscopy, and intensity modulated photocurrent spectroscopy, the conditions of the internal electron transport and transfer of ZnO‐based DSSCs are tested and analyzed. The results indicate that the ZnO NRs/NSs photoanodes have properties of rapid electron transport and high electron collection efficiency and show a relatively large amount of dye absorption. Therefore, for DSSCs based on ZnO NRs/NSs with liquid electrolyte, the short‐circuit current density (Jsc), open‐circuit voltage (Voc), fill factor (FF), and photoelectric conversion efficiency (PCE) are 11.82 mA cm−2, 0.66 V, 0.58, and 4.59 %, respectively. The PCE of the DSSCs is improved by 178.18 % compared to that of pure ZnO NRs cells (1.65 %) and is improved by 21.42 % with respect to pure ZnO NSs cells (3.78 %).

Preparation of rGO/ZnO photoanodes and their DSSCs performance

“…Therefore, graphene may be applied in the field of dielectric materials according to Panahi-Sarmad et al [3] and Bharatiya et al [4], as a supercapacitor according to Kumar et al [5] and Zhu et al [6], and in photovoltaic devices according to Chang et al [7] and Ubani et al [8]. Dye-sensitized solar cells (DSSCs) are devices that transfer solar energy to electrical energy, and the photoanodes of DSSCs, * E-mail: jiakeli.jci@163.com which have a significant effect on efficiency of the cells, are usually made up of ZnO according to Cheng et al [9], TiO 2 according to Ei-Ghamri et al [10], and SnO 2 according to Zatirostami [11]. In the process of light absorption and electron generation of DSSCs, there are many defects (such as vacancies, impurities, and interface) in the interface between dyes and particles or between photoanodes and fluorine-doped tin oxide (FTO) glass, which reduces the generation and transmission of electrons and holes and increases the recombination, resulting in the reduction of photoelectric performance of DSSCs according to Babar et al [12] and Dhamodharan et al [13].…”

The Cell Performances of DSSCs with ZnO Nanorod Electrodes

“…Dye-sensitized solar cells (DSSCs) can be still considered as a promising alternative to siliconbased solar cells due to low production cost, non-vacuum fabrication processes and using environmentally materials and production technology. Many research groups have investigated the crucial aspects affecting the DSSC working performances, such as the photon absorption of the dye molecules, that mesoporous materials and structures TiO2 as well as the electrolytes [1][2][3]. There are some approaches to enhance the light absorption, such as (i) by developing nanostructured TiO2 with larger porosity to increase dye loading capacity, (ii) by introducing a scattering layer on the top of TiO2 nanoparticles to produce back reflection of the transmitted light into TiO2 layer, and (iii) by using nanorod morphology to increase the larger surface area [3,4].…”