▎ 摘　　要

Purpose The purpose of this paper is to investigate the chemical, optical and photovoltaic properties of titanium dioxide/reduced graphene oxide (TiO2/rGO) photoanodes immersed in natural Roselle and synthetic (N719) dyes for dye-sensitized solar cell (DSSC) application. Design/methodology/approach TiO2 mixed with rGO were doctor-bladed on fluorine doped tin oxide (FTO) glass substrate. The chemical and optical properties of TiO2/rGO photoanodes immersed in Roselle and N719 dyes were characterized using Fourier-transformed infrared (FTIR) and ultraviolet-visible (UV-vis) spectroscopies, respectively. The DSSC's photovoltaic performances were tested using Visiontec Solar I-V tester at standard illumination of AM1.5 and irradiance level of 100 mW/cm(2). Findings The presence of anthocyanin dye from Roselle flower was detected at 604 nm and 718 nm. TiO2/rGO+Roselle dye sample revealed the smallest energy gap of 0.17 eV for ease of electron movement from valence band to conduction band. The TiO2/rGO-based DSSC fabricated with Roselle dye had a power conversion efficiency, n of 0.743 per cent higher than TiO2/rGO photoanode sensitized with N719 dye (0.334 per cent). The obtained J-V curves were analyzed by a single-diode model of Lambert W-function and manual optimization to determine the internal electrical parameters of the DSSC. The average and uncertainty values of J(sc) and n were evaluated at different R-sh range of 1362 omega to 32 k omega. Originality/value New ideality factor of TiO2/rGO-based DSSC was re-determined around 0.9995.