Control of Structural and Electrical Properties of Indium Tin Oxide (ITO)/Cu(In,Ga)Se 2 Interface for Transparent Back-Contact Applications

Yu Seung Son, Hyeonggeun Yu, Jong Keuk Park, Won Mok Kim, Seung Yeop Ahn, Wonjun Choi, Donghwan Kim, Jeung Hyun Jeong

Research output: Contribution to journalArticlepeer-review

21 Citations (Scopus)


Development of transparent-conducting oxide (TCO) back contact for Cu(In,Ga)Se 2 (CIGS) absorber is crucial for bifacial CIGS photovoltaics. However, inherent GaO x formation at the TCO/CIGS interface has hampered the photocarrier extraction. Here, by controlling the Na doping scheme, we show that the hole transporting properties at the indium-tin oxide (ITO)/CIGS back contact can be substantially improved, regardless of the GaO x formation. Na incorporation from the glass substrate during the GaO x forming phase created defective states at the interface, which allowed efficient hole extraction from CIGS, while post Na treatment after GaO x formation did not play such a role. Furthermore, we discovered that an almost GaO x -free interface could be made by reducing the underlying ITO film thickness, which revealed that ITO/CIGS junction is inherently Schottky. In the GaO x -free condition, post-Na treatment could eliminate the Schottky barrier and create ohmic junction due to generation of conducting paths at the interface, which is supported by our photoluminescence analysis.

Original languageEnglish
Pages (from-to)1635-1644
Number of pages10
JournalJournal of Physical Chemistry C
Issue number3
Publication statusPublished - 2019 Jan 24

Bibliographical note

Funding Information:
This work was supported by the internal program of Korea Institute of Science and Technology (KIST), by the Korea Institute of Energy Technology Evaluation and Planning (KETEP) and the Ministry of Trade, Industry & Energy (MOTIE) (Nos. 20153030013060, 20158520000060), and by the Technology Development Program to Solve Climate Changes of the National Research Foundation (NRF) funded by the Ministry of Science, ICT & Future Planning (No. 2016M1A2A2936782) of Republic of Korea.

Publisher Copyright:
© 2019 American Chemical Society.

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • General Energy
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films


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