Atomic-level chemical reaction promoting external quantum efficiency of organic photomultiplication photodetector exceeding 108% for weak-light detection

Linlin Shi, Yizhi Zhu, Guohui Li*, Ting Ji, Wenyan Wang, Ye Zhang, Yukun Wu, Yuying Hao, Kaiying Wang, Jun Yuan, Yingping Zou, Beng S. Ong*, Furong Zhu*, Yanxia Cui*

*Corresponding author for this work

Research output: Contribution to journalJournal articlepeer-review

Abstract

Low-cost, solution-processed photomultiplication organic photodetectors (PM-OPDs) with external quantum efficiency (EQE) above unity have attracted enormous attention. However, their weak-light detection is unpleasant because the anode Ohmic contact causes exacerbation in dark current. Here, we introduce atomic-level chemical reaction in PM-OPDs which can simultaneously suppress dark current and increase EQE via depositing a 0.8 nm thick Al2O3 by the atomic layer deposition. Suppression in dark current mainly originates from the built-in anode Schottky junction as a result of work function decrease of hole-transporting layer of which the chemical groups can react chemically with the bottom surface of Al2O3 layer at the atomic-level. Such strategy of suppressing dark current is not adverse to charge injection under illumination; instead, responsivity enhancement is realized because charge injection can shift from cathode to anode, of which the neighborhood possesses increased photogenerated carriers. Consequently, weak-light detection limit of the forwardly-biased PM-OPD with Al2O3 treatment reaches a remarkable level of 2.5 nW cm−2, while that of the reversely-biased control is 25 times inferior. Meanwhile, the PM-OPD yields a record high EQE and responsivity of 4.31 × 108% and 1.85 × 106 A W−1, respectively, outperforming all other polymer-based PM-OPDs.

Original languageEnglish
Pages (from-to)928-937
Number of pages10
JournalScience Bulletin
Volume68
Issue number9
DOIs
Publication statusPublished - 15 May 2023

Scopus Subject Areas

  • General

User-Defined Keywords

  • Al2O3
  • Atomic layer deposition
  • Interfacial
  • Organic photodetectors
  • Photomultiplication
  • Weak-light detection

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