Interfacial charge transfer study of hexacarbonitrile-based intermediate connecter in blue tandem organic light-emitting diodes

Huaixin Wei; Rong Zhang; Guangyao Huang; Yi Yuan; Wencheng Chen

doi:10.1016/j.optmat.2022.112345

Author(s)

Huaixin Wei
Rong Zhang
Guangyao Huang
Yi Yuan
Wencheng Chen

Related Research Unit(s)

Centre of Super-Diamond and Advanced Films

Detail(s)

Original language	English
Article number	112345
Journal / Publication	Optical Materials
Volume	128
Online published	19 Apr 2022
Publication status	Published - Jun 2022

Link(s)

DOI	DOI https://doi.org/10.1016/j.optmat.2022.112345 Final Published version
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Link to Scopus	https://www.scopus.com/record/display.uri?eid=2-s2.0-85128255194&origin=recordpage
Permanent Link	https://scholars.cityu.edu.hk/en/publications/publication(544d1c69-c4f4-4317-b32e-6b9380db2a51).html

Abstract

The charge generation process of hexaazatriphenylene hexacarbonitrile-based intermediate connectors (ICs) in blue tandem organic light-emitting diodes (OLEDs) is investigated via photoelectron spectroscopic and device studies. Though 1,4,5,8,9,11-hexaazatriphenylene hexacarbonitrile (HATCN) is well-known to be a p-type hole-injection layer, our photoelectron spectroscopic results indicate that HATCN becomes the n-type when it is sandwiched between Li-doped 4,7-diphenyl-1,10-phenanthroline (BPhen) and N,N″-diphenyl-N,N″-bis(1-naphthyl)-(1,1′-biphenyl)-4,4′-diamine (NPB) layers, and the charge generation and separation at the Li:BPhen/HATCN/NPB interfaces become energetically favorable, as depicted by their energy level alignments. This explains the superior device performance when Li:BPhen/HATCN/NPB is used as a connecting unit in tandem devices.