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

16 Scopus citations

Abstract

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
Volume48
DOIs
StatePublished - Jun 2018

Keywords

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

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