Perspective on Host Materials for Thermally Activated Delayed Fluorescence Organic Light Emitting Diodes

Abstract

Organic light emitting diode (OLED) is a new yet promising technology that is anticipated to replace the liquid crystal display technology in the very near future. The development of both the emitter and host materials for OLEDs is indispensable to realize high device efficiency and optimal performance. Though the presently commercialized OLED panels mostly utilize phosphorescence emitters, the all‐organic thermally activated delayed fluorescence (TADF) emitting materials have some obvious advantages. Considerable progress has been made in search of better performing TADF OLEDs in the past few years. Although major research attention has been drawn toward reporting new TADF emitters, the hosts are equally important in TADF OLEDs, as the doped films of the emitters mostly yield better results than the nondoped films. There are already some good reviews on the TADF emitters in literature. In this review article, the literature data specifically aimed at hosting TADF dopants are carefully selected and comprehensively summarized and categorized into several sub‐groups based on their structural features to draw the attention of the organic electronics research community toward developing new host materials for TADF OLEDs.

Acridan‐Grafted Poly(biphenyl germanium) with High Triplet Energy, Low Polarizability, and an External Heavy‐Atom Effect for Highly Efficient Sky‐Blue TADF Electroluminescence

“…without a host) in the emitting layer (EML) . Thus, EMLs with a host–guest strategy are usually employed with a TADF material as the guest dispersed uniformly in the host matrix to suppress TTA . To date, for state‐of‐the‐art TADF OLEDs with external quantum efficiency (EQE) over 30 % the host–guest strategy has been used in the EML .…”

Development of Materials for Blue Organic Light Emitting Devices

“…In this regard, a review regarding TADF host materials is also published to highlight the current achievements and prospects. [77] Though most of the host materials have shown brilliant device performances, however, industrialization requires a balance between efficiency and operational stability and this should be borne in mind when designing new material systems. Despite the fast development of blue materials for OLEDs, there are still many challenges, particularly the lifetime issue.…”

Stimuli-Responsive Thermally Activated Delayed Fluorescence in Polymer Nanoparticles and Thin Films: Applications in Chemical Sensing and Imaging

“…In sensing or imaging applications, seclusion of the TADF emitter to control aggregation, limit the influence of environmental factors, and introduce solubility in aqueous systems is the primary goal in host material selection and can be efficiently achieved through incorporation in a polymer host. Characteristics such as charge mobility have minimal effect on sensors unlike small molecule hosts typically used in TADF OLEDs (Chatterjee and Wong, 2019). Such polymer encapsulation can be performed by covalent or non-covalent interactions, with minimal effect on the absorption spectrum of the TADF material.…”