Solar energy conversion by the regular array of TiO2 nanotubes anchored with ZnS/CdSSe/CdS quantum dots formed by sequential ionic bath deposition

Abstract

The photoanode electrode of TiO2 nanotubes (NTs) anchored with ZnS/CdSSe/CdS quantum dots (QDs) was prepared by anodization of Ti metal and successive ionic layer adsorption and reaction (SILAR) procedure. The tuning of the band gap of CdSSe was done with controlled composition of Cd, S, or Se during the SILAR. A ladder-like energy structure suitable for carrier transfer was attained with the photoanode electrode. The power conversion efficiency (PCE) of our solar cell fabricated with the regular array of TiO2 NTs anchored with CdSSe/CdS or CdSe/CdS QDs [i.e., (CdSSe/CdS /TiO2NTs) or (CdSe/CdS /TiO2NTs )] was PCE = 3.49% and 2.81% under the illumination at 100 mW/cm2, respectively. To protect the photocorrosion of our solar cell from the electrolyte and to suppress carrier recombination, ZnS was introduced onto CdSSe/CdS. The PCE of our solar cell with the structure of a photoanode electrode, (ZnS/CdSSe/CdS/TiO2 NTs/Ti) was 4.67% under illumination at 100 mW/cm2.