Role of Na in solution-processed CuInSe2 (CISe) devices: A different story for improving efficiency

Shanza Rehan, Jihyun Moon, Tae Gun Kim, Jihye Gwak, Juran Kim, Jeong Won Kim, William Jo, Seung Kyu Ahn, Se Jin Ahn

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


Na has been believed to improve the device parameters of open circuit voltage (VOC) and fill factor (FF) presumably by increasing the carrier concentration (NA) of vacuum-processed Cu(In,Ga)Se2 films. In solution-processed CI(G)Se devices as well, Na reportedly increases VOC and FF but this improvement is not correlated with the increase in NA, suggesting a different physical mechanism associated with Na in solution-based routes. In this contribution, experimental results on the role of Na addition in solution-processed CISe films and devices were reported, in which Na addition had no influence on NA nor on film composition in spite of the notable increase in the device efficiency. On the contrary, Na was found to mitigate the interfacial recombination by reducing the undesirable surface defects. Along with this understanding, Na addition in our air-processable route resulted in a CISe device with 12.83% efficiency, which is comparable to the current world record efficiency of solution-processed CISe devices.

Original languageEnglish
Pages (from-to)401-412
Number of pages12
JournalNano Energy
StatePublished - Jun 2018

Bibliographical note

Funding Information:
This work was conducted under the framework of the Research and Development Program of the Korea Institute of Energy Research ( B8-2425 ). This work was also supported by the Korea Institute of Energy Technology Evaluation and Planning (KETEP), granted financial resource from the Ministry of Trade, Industry & Energy, Republic of Korea (No. 20163010012430 ) 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 ( 2016M1A2A2936753 ).

Publisher Copyright:
© 2018 Elsevier Ltd


  • CuInSe
  • Defects
  • Non-vacuum
  • Recombination
  • Sodium
  • Solar cells


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