Tetraoctylammonium Bromide Interlayer between NiLiOx and Perovskite for Light-Emitting Diodes

Van Khoe Vo, Sung Hoon Bae, Thi Huong Thao Dang, Dinh Hoat Phung, Juhan Kim, Seungwon Lee, Nayoon Lee, Hyo Jun Lim, Ki Hee Kim, Joon Hyung Lee, Young Woo Heo

Research output: Contribution to journalArticlepeer-review

Abstract

Physical vapor deposition is a favorable technique for fabricating light-emitting diodes (LEDs) due to its scalability and reproducibility. However, the performances of LEDs fabricated via this method are worse than those prepared via solution processing owing to the generation of high defect densities. In this study, we introduce a layer of tetraoctylammonium bromide (TOABr), an interfacial-modification compound containing four long octyl chains that are symmetrically arranged around an N atom, to reduce nonradiative recombination and trap densities in CsPbBr3. We examined the impacts of adding TOABr on perovskite thin films deposited on hole injection layers made of Li-doped NiOx and poly(3,4-ethylenedioxythiophene)/polystyrenesulfonate. Our investigations reveal that TOABr addition slightly increases crystallinity, dramatically increases photoluminescence, and achieves the preferred orientation in the perovskite films. Additionally, the interfacial layer passivates defects and improves charge balance in the device, thereby enhancing performance. Consequently, perovskite LEDs with a TOABr layer exhibit a lower turn-on voltage of 3 V than their pristine counterparts, achieving a maximum luminance of 11,133 cd m-2 and an external quantum efficiency of 1.24%, whereas the pristine perovskite LEDs achieve an EQE of 0.015%. The approach proposed in this study can be used to fabricate efficient vacuum-thermal-evaporated perovskite LEDs.

Original languageEnglish
Pages (from-to)64210-64221
Number of pages12
JournalACS Applied Materials and Interfaces
Volume16
Issue number46
DOIs
StatePublished - 20 Nov 2024

Keywords

  • CsPbBr
  • inorganic perovskite
  • interlayer
  • light-emitting diodes
  • perovskite
  • vacuum thermal evaporation

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