Performance of pyrocatechol violet and carminic acid sensitized ZnO/CdS nanostructured photoactive materials for dye sensitized solar cell

Abstract

In this study, ZnO and CdS deposited ZnO nanostructured material was successfully synthesized by using co-precipitation and ultra-sonication methods, respectively. A comparative study of the sensitization of ZnO and nanostructured ZnO/CdS with two different dyes (carminic acid and pyrocatechol violet) and applications of the synthesized material in solid state dye sensitized solar cells (DSSCs) are reported here. The characterization of the materials was performed by using x-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–visible spectroscopy, and Fourier transform infrared spectroscopy (FTIR). The SEM and TEM results showed that surface of ZnO nano spheres is well covered with CdS. UV–visible spectrum showed the rise of a new optical band due to CdS deposition which effectively tuned the band gap of ZnO from 3.12 eV to 1.877 eV. XRD analysis revealed the successful formation of hexagonal phases of CdS and ZnO. The materials were applied as photoanodes in DSSCs with and without dye sensitization. P3HT (Poly (3-hexylthiophene) was used as a hole conducting polymer. CdS deposition and sensitization with different dyes showed a significant effect on the overall efficiency of fabricated devices. The ZnO/CdS based DSSC sensitized with carminic acid showed a current density (Jsc) of 8.72 mA/cm2 with an open circuit voltage (Voc) of 0.43 V and an overall efficiency of 1.42%. While the same photoanode material sensitized with pyrocatechol violet gave Jsc value of 9.13 mA/cm2 with a Voc of 0.39 V and an overall efficiency of 1.55%.