Optical Properties and Performance of Pristine and Ag‐Doped ZnO as Working Electrode in Dye‐Sensitized Solar Cells

ABSTRACT Dye‐sensitized solar cell (DSSC) is a potential low‐cost solar energy conversion device that is simple to fabricate with low cost than traditional silicon‐based solar cells. The development of DSSC is hampered by the limitations of using ZnO‐based photoanodes for a number of reasons (e.g., charge recombination, efficiency and expensive method). Photoanode material is one of the crucial components in DSSC, which plays a vital role in overall device performance, and the improvement of photoanode materials is needed. This work is focused to improve the overall performance of DSSCs with reducing problem by incorporating a dopant into ZnO semiconductor material as photoanode. Pristine and silver‐doped zinc oxide (Ag‐ZnO) photoanodes with various weight percentages of Ag (2, 3 and 4 wt%) were prepared by a facile, cost‐effective and quick green‐modified–solvothermal method with diethylamine (precipitating agent) and fig leaf extract (capping agent). The structural, crystalline nature, morphological and optical properties of prepared nanomaterials were analysed using X‐ray diffraction (XRD), field emission scanning electron microscopy (FE‐SEM) and UV–Vis spectrophotometry. The results revealed that the crystallite size of pristine and Ag‐ZnO with 2, 3 and 4 wt% of Ag decreased from 85 to 21 nm by increasing the percentage of Ag. The surface roughness decreased with increasing the weight percentage of Ag, and there is no big change in their morphology. The energy band gaps (E g ) of pristine and Ag‐ZnO with 2%, 3% and 4% Ag determined by Tauc plot were 2.55, 3.05, 3.09 and 3.17 eV, respectively. Among the pristine and Ag‐doped ZnO fabricated devices, the photovoltaic measurements of 4% Ag‐ZnO exhibited superior performance reaching the highest efficiency of 2.25% with a short‐circuit current density (J SC ) of ~5.8 mA/cm 2 , an open‐circuit voltage (V OC ) of ~810 mV and a fill factor (FF) of ~0.54, which might be due to large optical band gap, better conductivity, reduced recombination rate and enhanced dye adsorption.