Band gap engineering of atomic layer deposited ZnxSn1-xO buffer for efficient Cu(In,Ga)Se2 solar cell

Raphael Edem Agbenyeke, Soomin Song, Bo Keun Park, Gun Hwan Kim, Jae Ho Yun, Taek Mo Chung, Chang Gyoun Kim, Jeong Hwan Han

Research output: Contribution to journalArticlepeer-review


Ternary zinc tin oxide (ZTO) is one of the few environmental compatible buffer materials with the potential of replacing the n-CdS buffer in Cu(In,Ga)Se2 (CIGS) solar cells and other photovoltaic systems once its properties are fully understood and optimized. In this work, ZTO films were grown by atomic layer deposition and were logically characterized with the aim of understanding the correlations between compositional changes and film properties. The ZnO:SnO2 pulse ratio significantly affected the growth rate, crystal structure, morphology, and band gap of the ZTO films. By controlling the Sn/(Sn + Zn) atomic ratio, the optical band gap of the ZTO films was tuned between 3.05 and 3.36 eV. Integrating the ZTO films as buffer layers in CIGS solar cells, we observed that films with Sn concentrations of 9 to 16 at.% yielded photo-conversion efficiency close to 14%, which was very comparable to efficiency attained with the commonly used CdS buffer. Furthermore, using X-ray photoelectron spectroscopy analysis, we correlated the current-voltage behavior of the cells to the conduction band offset at the ZTO/ CIGS interface.

Original languageEnglish
Pages (from-to)745-751
Number of pages7
JournalProgress in Photovoltaics: Research and Applications
Issue number9
Publication statusPublished - 2018 Sept

Bibliographical note

Funding Information:
This work was supported by Korea Research Institute of Chemical Technology (SI1803, development of smart chemical materials for IoT device).

Publisher Copyright:
Copyright © 2018 John Wiley & Sons, Ltd.

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Renewable Energy, Sustainability and the Environment
  • Condensed Matter Physics
  • Electrical and Electronic Engineering


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