Contribution of Sub-Gap States to Broadband Infrared Response in Organic Bulk Heterojunctions

Ning Li, Insun Park, Jarrett H. Vella, Soong Ju Oh, Jason D. Azoulay, Dong Seok Leem, Tse Nga Ng

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)


This work studied a series of infrared detectors comprised of organic bulk heterojunctions to explain the origin of their broadband spectral response from the visible to the infrared spanning 1 to 8 μm and the transition from photonic to bolometric operation. Through comparisons of the detector current and the sub-bandgap density of states, the mid- and long-wave infrared response was attributed to charge trap-and-release processes that impact thermal charge generation and the activation energy of charge mobility. We further demonstrate how the sub-bandgap characteristics, mobility activation energy, and effective bandgap are key design parameters for controlling the device temperature coefficient of resistance, which reached up to -7%/K, better than other thin-film materials such as amorphous silicon and vanadium oxide.

Original languageEnglish
Pages (from-to)53111-53119
Number of pages9
JournalACS Applied Materials and Interfaces
Issue number47
Publication statusPublished - 2022 Nov 30

Bibliographical note

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© 2022 American Chemical Society. All rights reserved.


  • bulk heterojunction
  • infrared detectors
  • organic semiconductors
  • sub-bandgap states
  • temperature coefficient of resistance

ASJC Scopus subject areas

  • General Materials Science


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