Expand this Topic clickable element to expand a topic
Skip to content
Optica Publishing Group

Highly Efficient Organic Light-Emitting Diode Based on a Hidden Thermally Activated Delayed Fluorescence Channel in a Heptazine Derivative

Not Accessible

Your library or personal account may give you access


Considerable progress in organic light-emitting diodes (OLEDs) has triggered intensive effort to develop efficient solid-state electroluminescent (EL) materials over the past two decades. Among the many classes of materials being investigated, transition metal complexes are highly attractive because phosphorescent OLEDs containing Ir (III), Pt (II) and Os (II) complexes exhibit very high external quantum efficiencies (ηext). This is because such complexes effectively harvest triplet excitons, so their efficiencies are four times higher than that of conventional fluorescent OLEDs. However, phosphorescent OLEDs containing transition metal-based compounds are rather expensive and unsustainable because they contain rare metals. While OLEDs containing Cu (I) complexes that exhibit high ηext comparable to those with transition metal complexes have been examined as an alternative, the relatively low reliability and high driving voltage of such OLED are fundamental problems. Therefore, a novel way to realize high EL efficiency is required. Although fluorescent OLEDs have been assumed to show limited efficiency because of the branching ratio of singlet and triplet excitons of 1:3, the most recent fluorescence-based OLEDs have overcome this limitation using triplet-triplet annihilation and thermally activated delayed fluorescence (TADF) [1-2]. In particular, we have developed promising blue and green TADF materials [3-4]. However, the design of efficient orange or red emitters is inherently difficult because the photoluminescence (PL) quantum efficiency tends to decrease as the emission wavelength increases according to the energy gap law.

© 2013 Optical Society of America

PDF Article
More Like This
Highly Efficient Organic Light-Emitting Diodes with Completely Oriented Delayed Fluorescent Emitters

Takeshi Komino, Yuta Sagara, Hiroyuki Tanaka, Yuji Oki, Nozomi Nakamura, Hiroshi Fujimoto, and Chihaya Adachi
CE_3_4 The European Conference on Lasers and Electro-Optics (CLEO_Europe) 2017

High efficiency organic light-emitting diodes with conventional fluorescent emitters

Hajime Nakanotani and Chihaya Adachi
DW5C.1 Solid-State and Organic Lighting (SOLED) 2014


You do not have subscription access to this journal. Citation lists with outbound citation links are available to subscribers only. You may subscribe either as an Optica member, or as an authorized user of your institution.

Contact your librarian or system administrator
Login to access Optica Member Subscription

Select as filters

Select Topics Cancel
© Copyright 2022 | Optica Publishing Group. All Rights Reserved