Bandgap-graded Cu2Zn(Sn1-xGex)S 4 thin-film solar cells derived from metal chalcogenide complex ligand capped nanocrystals

Inhyuk Kim, Kyujin Kim, Yunjung Oh, Kyoohee Woo, Guozhong Cao, Sunho Jeong, Jooho Moon

Research output: Contribution to journalArticlepeer-review

93 Citations (Scopus)


We demonstrate organic residue free, bandgap-graded Cu 2Zn(Sn1-xGex)S4 (CZTGeS) thin-film solar cells based on metal chalcogenide complex (MCC) ligand capped nanocrystals (NCs). The bandgap of the CZTGeS films is tuned by varying the amount of Sn2S64- MCC ligand absorbed on the surface of the Cu2ZnGeS4 (CZGeS) NCs, without an undesirable postselenization process. Using CZGeS NCs inks with three different Sn/(Ge+Sn) ratios, bandgap-graded CZTGeS thin films are obtained via multicoating and annealing procedures. Compositional and spectroscopic analyses along the film thickness confirm that the band-graded CZTGeS absorber layer, with a gradually increasing bandgap from the back contact to the p-n junction, is successfully accomplished. Compared with an ungraded band structured CZTGeS cell, this normal grading structure facilitates both higher short circuit current and open-circuit voltage, facilitating a power conversion efficiency of 6.3%.

Original languageEnglish
Pages (from-to)3957-3965
Number of pages9
JournalChemistry of Materials
Issue number13
Publication statusPublished - 2014 Jul 8

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Chemistry


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