Molecular self-assembled designing and characterization of TiO2 NPs-CdS QDs-dye composite for photoanode materials

Abstract

Ternary based photoanodes have been prepared by using titanium dioxide (TiO2) nanoparticles (NPs), cadmium sulfide (CdS) quantum dots (QDs) and N719 dye. Initially, CdS QDs and TiO2 NPs were synthesized by one pot synthesis and sol-gel method, respectively. CdS QDs were connected electrostatically to the surfaces of TiO2 NPs, and after that, this binary hybrid further self-assembled with N719 dye to form the composites. The NPs, QDs and the resultant composites are characterized by using different techniques. The connectivity of these anatase TiO2 NPs with cubic CdS QDs are confirmed by FTIR; while the broad coverage of these materials is studied through UV–Visible diffuse reflectance spectroscopy (DRS). The surface topology and the cross-sectional morphology of thin films are studied by high resolution transmission electron microscopy (HR-TEM) and field emission scanning electron microscopy (FE-SEM) techniques; while the structural properties of NPs and QDs are studied by X-ray diffractometer (XRD). The synergetic co-sensitization of CdS and N719 dye significantly enhancing the overall power conversion efficiency (η) of TiO2 up to 2.37% (Jsc = 10.31 mA/cm2 and Voc of 550 mV) (100 mW/cm2). The Jsc, Voc, and η values along with Incident photon to current conversion efficiency (IPCE) value of ternary photoelectrode-based solar devices, is almost double to that of either binary TiO2 NPs-CdS QDs or binary TiO2 NPs-N719 binary systems.