Lithium Incorporation into TiO₂ Photoanode for Performance Enhancement of Dye-Sensitized Solar Cells

Dye-sensitized solar cells (DSSCs) are one of the mostfavorablesolar cell technologies owing to their low cost and ease of fabrication.The electron transport layer, consisting of a mesoporous titaniumoxide (TiO2) photoanode, plays a crucial role in DSSCs.In this study, we performed a post-lithium (Li) treatment on TiO2 films to enhance the optoelectronic features and power conversionefficiency (PCE) of DSSCs. The material properties of pristine andLi-treated TiO2 films were examined by X-ray diffraction(XRD), atomic force microscopy (AFM), steady-state photoluminescence(PL), and X-ray photoelectron spectroscopy (XPS). Li treatment wasconfirmed to suppress defects and enhance the crystallinity of theTiO(2) films. Furthermore, TiO2 films sensitizedwith N719 dye were used as photoanodes and Pt as a counter electrodefor the fabrication of DSSCs. The devices with 0.1 M Li-TFSI treatmentshowed a performance improvement of & SIM;20%, with a PCE of 10.5%,while the control DSSC had a PCE of 8.7%. The device performance wassignificantly enhanced owing to improved structural properties, efficientcharge transport, and suppression of recombination owing to the passivationof trap states.