Electrodeposited mixed ZnS–CdS photoelectrode for natural dye-sensitized solar cells (NDSSC)

Abstract

Photoelectrodes and sensitizers are the vital components of future low-cost dye-sensitized solar cells which are used to meet the present energy demand. Herein, ZnS–CdS thin film photoelectrodes (WE) prepared on steel substrate by electrodeposition method are sensitized by chlorophyll extract and combined with graphite counter electrode, both being dipped in sulphide–polysulphide redox electrolytes (S2−/S n 2− ) to form the dye-sensitized solar cells with the following configuration: $${\text{photoelectrode}} + {\text{dye}}//{\text{Na}}_{2} {\text{S}}(1{\text{M}}) + {\text{NaOH}}(1{\text{M}}) + {\text{S}}(1{\text{M}})//{\text{C}}({\text{Graphite}}).$$ The photoelectrochemical characterizations of the dye-sensitized thin film photoelectrodes under investigation include current–voltage (I–V) characteristics in dark and light, spectral photoresponse and cells power output. Photoelectrodes are found to be n-type semiconductors. From the power output curves, the light-to-electricity conversion efficiency of dye-sensitized ZnS–CdS electrode (8 h sensitization)-based solar cells, short-circuit current density (Jsc) and open-circuit voltage (Voc) is found to be 0.29, 0.51 mA/cm2 and 0.34 V respectively. The PXRD results show that the fabricated mixed ZnS–CdS thin films are made up of nanocrystals of size ~ 9.12 nm. Surface morphology of the films is studied, and SEM micrograms establish the polycrystalline nature of mixed ZnS–CdS thin films. The EDAX (energy diffraction analysis of X-ray) results show the presence of Zn, Cd and S in the thin films.