Sharif University of Technology-International Campus, Faculty of Engineering and Science, Kish Island, Iran
A new strategy for enhancing the efficiency of TiO2 dye-sensitized solar cells (DSSCs) by doping foreign ion into TiO2 lattice via sol-gel process is reported. DSSCs are based on a semiconductor (i.e., TiO2), formed between a photo-sensitized anode and an electrolyte. In order to reach high conversion efficiency, it is important to increase the electron injection and optical absorption. One promising solution to increase the electron injection is to decrease the large band gap of TiO2 by doping a foreign ion into TiO2 lattice. In the present work, Ag- doped TiO2 nanopowders and thin films with different Ag:Ti ratios are reported. The effect of dopant WT% on photovoltaic performance of dye-sensitized solar cells were studied. The powders were synthesized via aqueous sol–gel route, followed by annealing at 500°C for 4hr. X-ray diffraction and Field emission scanning electron microscope (FE-SEM) analyses revealed that the synthesized samples had uniform grains in nanometer range. It was found that, 0.05 WT. % Ag-doped TiO2 DSSC (i.e., DSSC number 2) had the highest power conversion efficiency of 2.4%, short current density of 5.65 mA/cm2 and open circuit voltage of 761 mV. This can be related to achievement of an optimum condition balance among the electron injection, light scattering effect and dye sensitization. The applied method exhibited superior potential for synthesis of Ag-doped TiO2 nanopowders and films to utilize as DSSCs.