Preparation and characterization of cadmium sulfide quantum dot sensitized solar cell by Successive Ionic layers Adsorption and Reaction (SILAR) method

Abstract

This paper deals with the preparation of a cadmium sulfide (CdS) quantum dot-sensitized solar cell. The photoelectrode was prepared from glass slides with a layer of fluorine-doped tin oxide (FTO). A compact layer of titanium oxide was prepared by spin coating and a porous layer of nano porous titanium oxide by doctor blade. Then the quantum dots were deposited by Successive Ionic Layers Adsorption and Reaction (SILAR) method. The counter electrode was prepared from copper(I) sulfide on brass substrate. Finally, the solar cell was assembled by sandwich method using a conductive polysulfide electrolyte, with an effective area of ​​(0.3 x 0.35) cm².

The photoelectrode was characterized by XRD, and the resulting spectrum showed that titanium oxide is in the anatase phase. The thickness of the titanium oxide compact layer was measured by means of a roughness measuring device, and was found to be about 60 nm.

The counter electrode was characterized by XRD, and the resulting spectrum showed the structure of Cu_1.8S.

Quantum dots were characterized by molecular absorption spectroscopy (UV-VIS). The absorption spectrum showed an absorption shoulder at wavelength 474 nm, and fluorescence spectroscopy showed an emission peak at wavelength 492.5 nm using excitation wavelength 474.5 nm. The bandgap of the prepared quantum dots was calculated using Tauc method and a value of

 (Eg=2.65eV) was obtained. The diameter of the quantum dots was calculated using the effective mass approximation model, and it was about 7 nm.

The characteristic curve of the solar cell was measured using a halogen lamp and a rheostat. The Short-circuit current density t was 7.5 mA/cm², the open

circuit voltage was 470 mV, and the power conversion efficiency was 0.88%.