Nanocrystalline Polymorphic Energy Funnels for Efficient and Stable Perovskite Light-Emitting Diodes

Do Kyoung Lee, Yunseop Shin, Ho Jin Jang, Joo Hong Lee, Keonwoo Park, Woochan Lee, Seunghyup Yoo, Jun Yeob Lee, Dongho Kim, Jin Wook Lee, Nam Gyu Park

Research output: Contribution to journalArticlepeer-review

17 Citations (Scopus)


Charge carrier confinement in nanocrystals is an effective route to enhance luminescence efficiency of metal halide perovskites. However, difficulty in handling surface ligands of colloidal perovskite nanocrystals and the defective surface of the processed nanocrystals limit radiative efficiency and the stability of nanocrystalline films. We report a novel approach to fabricate highly luminescent nanocrystalline polymorphic formamidinium lead tri-iodide (FAPbI3) films. The cubic perovskite nanocrystals are formed in situ by kinetic controlled solid-state phase conversion of a hexagonal polymorph. The perovskite nanocrystal surface is benign owing to the remnant polymorph forming a type I heterojunction with the nanocrystal surface, facilitating accelerated radiative recombination with suppressed trapping in the nanocrystals to which ultrafast carrier funneling occurs. This polymorphic energy funnel renders photoluminescence intensity enhanced by a factor of 58 compared to that of conventional bulk-FAPbI3 film. A proof-of-concept light-emitting diode device exhibited superior efficiency and stability in comparison to devices based on the conventional bulk-FAPbI3 film.

Original languageEnglish
Pages (from-to)1821-1830
Number of pages10
JournalACS Energy Letters
Issue number5
Publication statusPublished - 2021 May 14

Bibliographical note

Funding Information:
This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MIST) under contract numbers NRF-2020R1F1A1067223, 2012M3A6A7054861 (Global Frontier R&D Program on Center for Multiscale Energy System), 2016M3D1A1027663, and 2016M3D1A1027664 (Future Materials Discovery Program) and by the Material and Component Industrial Future Growth Engine Program (20006476) funded by the Ministry of Trade, Industry & Energy (MOTIE).

Publisher Copyright:
© 2021 American Chemical Society.

All Science Journal Classification (ASJC) codes

  • Chemistry (miscellaneous)
  • Renewable Energy, Sustainability and the Environment
  • Fuel Technology
  • Energy Engineering and Power Technology
  • Materials Chemistry


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