学术文献库

The surface states of the active TiO2 layer is crucial while fabricating an efficient solar cell. This work experimentally analyses the effect of exposing TiO2 based electron transport layer (ETL) to the ultraviolet-ozone (UV-O3) and optimizes the exposure time for improving power conversion efficiency (PCE) of fabricated dye-sensitized solar cells (DSSCs). These results demonstrate that the performance of DSSCs can be improved significantly by UV-O3 exposure of sintered TiO2 photoanode surface, with the duration of exposure being a critical parameter. Fabricated devices show 33.01 % increase in PCE for the optimum exposure. Nevertheless, overexposure of the sample beyond the optimum time decreases the efficiency of the fabricated solar cells. The device with optimum exposure exhibits the highest PCE of 8.34% with short circuit current density (Jsc) of 15.15 mA/cm2, open circuit voltage (Voc) of 756 mV and Fill factor (FF) of 71.10%. This increase in efficiency is attributed to the enhanced crystallization and reduction in the organic contaminants C-C/C-H from 57.90 to 52.40% as shown by the X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), respectively. The XPS result further indicates an increase in oxygen vacancy from 12.40 to 23.40% for O 1s state and from 9.30 to 14.30% for Ti 2p state of Ti3+. Results from the Atomic Force Microscope (AFM) also confirms the minimized surface roughness of 16.36 nm for the optimally exposed TiO2 film, and increase in hydrophilicity leading to improved efficiency of the solar cells which were optimally exposed to UV-O3.