Growth of CdS and CdTe thin film semiconductors and fabrication of CdS/CdTe solar cells

No Thumbnail Available

Date

2015

Journal Title

Journal ISSN

Volume Title

Publisher

Faculty of Graduate Studies, University of Kelaniya

Abstract

Thin films of CdS and CdTe semiconductor materials were electrodeposited onto glass/fluorine doped tin oxide conducting glass surfaces using a potentiostat/galvanostat equipped with a three electrode cell. Aqueous electrolytic bath containing CdCl2 and (NH4)2S2O3 was used for the electrodeposition of CdS thin films. CdTe thin films were electrodeposited onto glass/FTO/CdS substrates from aqueous solution having high concentrations of CdSO4 and low concentrations of TeO2 and CdCl2. The glass/FTO/CdS/CdTe/Cu-Au solar cell devices were prepared by thermal evaporation of Cu and Au on CdTe surface. CdS films grown were annealed at ~400 °C for 15 minutes in air and photo-electro chemical (PEC) cell measurements were performed to identify the electrical conductivity type. Both as-deposited and annealed CdS layers were identified as n-type in electrical conduction. CdS thin films were shown enhanced PEC responses upon heat treatment. The respective band gap values for as-deposited and heat treated CdS were 2.35±0.05 eV and 2.40±0.05 eV which were close to the band gap of bulk CdS. XRD analysis of as-deposited CdS layers revealed the presence of hexagonal CdS materials with the major peak arising from (002) plane. Following the CdTe deposition on glass/FTO/CdS substrate, the surface of CdTe layers were coated with a 0.1% CdCl2 solution and structures were annealed at ~400°C for 10 minutes in air. Band gaps for CdTe layers were found to be 1.45±0.02 eV for both as-deposited and annealed samples which exhibited the band gap of bulk CdTe. There was a little improvement in cubic (220) and (311) peaks of XRD spectra of annealed CdTe layers compared to the as-deposited material, but annealing exhibited a small reduction of cubic phase preferential orientation (111). SEM images showed that CdS and CdTe layers were fairly uniform. The fabricated solar cell devices showed the efficiency of 2.1% with Voc ~330 mV, Jsc~20 mA cm-2 and FF~33% under the illumination of air mass (AM) 1.5 conditions (100 mW/cm2, 1 Sun).

Description

Keywords

Thin films, Semiconductors, Solar cells

Citation

Kumarasinghe, K.D.M.S.P.K., De Silva, D.S.M., Pathiratne, K.A.S., Dharmadasa, I.M., Salim, H.I., Abdul-Manaf, N.A., Ravirajan, P. and Balashangar, K. 2015. Growth of CdS and CdTe thin film semiconductors and fabrication of CdS/CdTe solar cells, p. 194, In: Proceedings of the International Postgraduate Research Conference 2015 University of Kelaniya, Kelaniya, Sri Lanka, (Abstract), 339 pp.

Collections

Endorsement

Review

Supplemented By

Referenced By