Electrical and optical characterization of the influence of chemical bath deposition time and temperature on CdS/Cu(In,Ga)Se2 junction properties in Cu(In,Ga)Se2 solar cells

• Published in: Thin solid films 2013-11, Vol.546, p.289-293
• Main Authors: Seo, Han-Kyu, Ok, Eun-A, Kim, Won-Mok, Park, Jong-Keuk, Seong, Tae-Yeon, Lee, Dong Wha, Cho, Hoon Young, Jeong, Jeung-hyun
• Format: Article
• Language: English
• Subjects: Cadmium; CADMIUM SULFIDE; Cadmium sulfides; CBD-CdS; CIGS solar cell; Condensed matter: electronic structure, electrical, magnetic, and optical properties; COPPER INDIUM SELENIDE; Cross-disciplinary physics: materials science; rheology; Defects; DEPOSITION; DIFFUSION; DLTS; ELECTRONIC PRODUCTS; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic transport phenomena in thin films and low-dimensional structures; Electronics; Exact sciences and technology; Impurities; Liquid phase epitaxy; deposition from liquid phases (melts, solutions, and surface layers on liquids); Materials science; Metastability; Methods of deposition of films and coatings; film growth and epitaxy; MICA; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of specific thin films; Photoluminescence; Physics; Recombination; SULFIDES; Surface and interface electron states; Surface states, band structure, electron density of states; Volt-ampere characteristics
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2013.05.024

The effects of varying the conditions for the chemical bath deposition (CBD) of cadmium sulfide (CdS) layers on CdS/Cu(In,Ga)Se2 (CIGS) hetero-junctions were investigated using photoluminescence (PL), electroluminescence (EL), deep level transient spectroscopy (DLTS), and red-light-illuminated current-voltage (I–V) measurements. We demonstrated that varying CBD-CdS conditions such as the temperature and time influenced the recombination pathways around the CdS/CIGS junction via the formation of different electronic defects, which eventually changed the photovoltaic conversion efficiency. As the CBD-CdS time and temperature were increased, the cell efficiency decreased. PL measurements revealed that this degradation of the cell efficiency was accompanied by increases in the defect-related recombination, which were attributed to the existence of donor defects around CdS/CIGS having an energy level of 0.65eV below conduction band, as revealed by DLTS. Increasing distortions in the red-light-illuminated I–V characteristics suggested that the related defects might also have played a critical role in metastable changes around the CdS/CIGS junction. Because the CBD-CdS time and temperature were considered to influence the diffusion of impurities into the CIGS surface, the evolution of the efficiency, PL spectra, defect populations, and red-light-illuminated I–V characteristics observed in this work could be attributed to the diffusion of impurities during the CBD-CdS process. •CdS layers were grown by chemical bath deposition (CBD).•The CBD-CdS influenced the efficiency of Cu(In,Ga)Se2 (CIGS) solar cell.•It could be related to slight alteration in carrier recombination around CdS/CIGS.•Photo- and electroluminescence spectra detected those alterations in recombination.•The variation of results could be related to the changes in deep-level defects.