The characteristics of Cu(In, Ga)Se 2 thin-film solar cells by bandgap grading

Young Ill Kim, Kee Jeong Yang, Se Yun Kim, Jin Kyu Kang, Juran Kim, William Jo, Hyesun Yoo, Jun Ho Kim, Dae Hwan Kim

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

We investigated the characteristics of Cu(In, Ga)Se 2 solar cells with bandgap (E g ) grading. Two precursor types were employed: Mo/Cu 0.75 Ga 0.25 /In/Ga 2 Se 3 (CIGSe-1) and Mo/Cu/In/Ga 2 Se 3 (CIGSe-2). In CIGSe-1, the range of depths with a high Ga content is wider than that in CIGSe-2; thus, the region in which the main electron-trapping clusters and high-population deep donor defects can form is larger, and the defect density is higher. In the defect energy level range, various other defects and defect clusters exist with a defect density of 2.83 × 10 15 cm −3 within the CIGS-1 absorber layer and 2.37 × 10 15 cm −3 within the CIGS-2 absorber layer. The average efficiency values are 5.71% for CIGSe-1 and 6.82% for CIGSe-2. Additionally, the average V OC deficit (E g /q − V OC ) values are 0.758 V for CIGSe-1 and 0.731 V for CIGSe-2. As a result, in the 7 CIGSe-2 samples, the open-circuit voltage and efficiencies are improved. Thus, it is demonstrated that appropriate E g grading in a CIGSe layer with a wider E g on the back surface can result in improved performance.

Original languageEnglish
Pages (from-to)437-442
Number of pages6
JournalJournal of Industrial and Engineering Chemistry
Volume76
DOIs
StatePublished - 25 Aug 2019

Keywords

  • Bandgap grading
  • CIGSe
  • Defect
  • Solar cell
  • Surface potential

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