Recombination Velocity Less Than 100 cm/s at Polycrystalline Al2O3/CdSeTe Interfaces

Darius Kuciauskas, John Moseley, Patricia Dippo, Wyatt Metzger, Jason Kephart, Walajabad Sampath

Research output: Contribution to journalArticlepeer-review

47 Scopus Citations


Reducing recombination in polycrystalline solar cells by orders of magnitude is currently one of the greatest challenges for increasing thin-film solar cell efficiency to theoretical limits. The question of how to do this has been a challenge for the thin-film community for decades. This work indicates that effective interface passivation is critical. Here, polycrystalline Al2O3/CdSeTe/Al2O3/glass heterostructures are grown, and a combination of spectroscopic, microscopic, and time-resolved electro-optical measurements demonstrates that the interface recombination velocity at alumina/thin-film interfaces can be less than 100 cm/s. This is three orders of magnitude less than typical CdTe interfaces without passivation, commensurate with single-crystal epitaxial CdMgSeTe/CdSeTe/CdMgSeTe double heterostructures, and enables minority-carrier lifetimes in polycrystalline CdSeTe well above 100 ns. Microscopic interfacial electric-field measurements identify the field effect as a potential mechanism for polycrystalline Al2O3/CdSeTe interface passivation. The results provide guidance for modeling and interface passivation in devices and indicate future paths to realize highly efficient thin-film solar cells.

Original languageAmerican English
Article number263901
Number of pages5
JournalApplied Physics Letters
Issue number26
StatePublished - 25 Jun 2018

Bibliographical note

Publisher Copyright:
© 2018 Author(s).

NREL Publication Number

  • NREL/JA-5900-71105


  • emission spectroscopy
  • heterojunctions
  • passivation
  • second harmonic generation
  • solar cells
  • spectroscopy
  • thin films
  • time resolved spectroscopy


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