Work

Deep Blue Exciplex Organic Light‐Emitting Diodes with Enhanced Efficiency; P‐type or E‐type Triplet Conversion to Singlet Excitons?

Year: 2012

Type: article

Abstract: Simple trilayer, deep blue, fluorescent exciplex organic light-emitting diodes (OLEDs) are reported. These OLEDs emit from an exciplex state formed between the highest occupied molecular orbital (HOMO) of N,N'-bis(1-naphthyl)N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine (NPB) and lowest unoccupied molecular orbital (LUMO) of 1,3,5-tri(1-phenyl-1H-benzo[d]imidazol-2-yl)phenyl (TPBi) and the NPB singlet manifold, yielding 2.7% external quantum efficiency at 450 nm. It is shown that the majority of the delayed emission in electroluminescence arises from P-type triplet fusion at NPB sites not E-type reverse intersystem crossing because of the presence of the NPB triplet state acting as a deep trap.

Source: Advanced Materials

DOI: 10.1002/adma.201203615

Authors: Vygintas Jankus, Chien‐Jung Chiang, Fernando Dias, Andrew P. Monkman

Institution: Durham University

Language: English

Topic: Organic Light-Emitting Diodes Research

Subfield: Electrical and Electronic Engineering

Field: Engineering

Domain: Physical Sciences

Open Access status: green

Funder: Engineering and Physical Sciences Research Council

Awards: Solving the NIR dilemma for organic photovoltaics, The Energy Agenda: Exciplex blend small-molecule OLEDs; high performance fluorescent devices from E-type triplet harvesting, High triplet energy polymers for blue phosphorescent, solution-processable multilayer PLEDs to develop solid-state lighting, Charge Transfer States in D-A Excitonic Solar Cells: Photophysical Characterization and Loss Mechanisms for Charge Generation