Effects of the Cu/(Ga+In) ratio on the bulk and interface properties of Cu(InGa)(SSe)2 solar cells

Dongho Lee, JungYup Yang, Young Su Kim, Chan B. Mo, Sungchan Park, ByoungJune Kim, Dongseop Kim, Junggyu Nam, Yoon Mook Kang

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

In this study, we systematically investigated the performance loss factors in Cu(InGa)(SSe)2 (CIGSSe) solar cells with various Cu/(Ga+In) (CGI) ratios, which were fabricated with sputtering and sequential selenization/sulfurization processes. The effects of the CGI ratio on the CIGSSe solar cells were determined by measuring the current-voltage (IV) curves and junction capacitance of the solar cells, as well as by performing X-ray analysis techniques on the cells. An increase in the defect density and decrease in the free carrier density were observed in samples with high Cu concentrations (CGI ratio >0.89), which resulted in a drastic decrease in the open-circuit voltage (VOC) and fill factor (FF). The temperature-dependent IV (IVT) and X-ray diffraction (XRD) results of the bulk characterization corresponded well with the capacitance measurements for all CGI ratios. The low crystal quality and short minority-carrier diffusion length at high CGI ratios resulted in a significant bulk recombination rate. A qualitative analysis of the interface characteristics was performed with IVT measurements, and the results showed that the recombination activation energy in the samples with high CGI ratios was lower than the bandgap (Eg), decreasing the VOC of these devices. For the samples with high CGI ratios, their inferior bulk and interface characteristics caused recombination to occur at the interface as well as in the bulk. However, the interface recombination rate was negligible for the samples with low CGI ratios (CGI ratio

Original languageEnglish
Pages (from-to)195-203
Number of pages9
JournalSolar Energy Materials and Solar Cells
Volume149
DOIs
Publication statusPublished - 2016 May 1

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Keywords

  • Bulk
  • CIGSSe
  • Defects
  • Interface
  • Recombination

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Electronic, Optical and Magnetic Materials
  • Surfaces, Coatings and Films

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