Organic materials that exhibit thermally activated delayed fluorescence (TADF) are an attractive class of functional materials that have witnessed a booming development in recent years. Since Adachi et al. reported high-performance TADF-OLED devices in 2012, there have been many reports regarding the design and synthesis of new TADF luminogens, which have various molecular structures and are used for different applications. In this review, we summarize and discuss the latest progress concerning this rapidly developing research field, in which the majority of the reported TADF systems are discussed, along with their derived structure–property relationships, TADF mechanisms and applications. We hope that such a review provides a clear outlook of these novel functional materials for a broad range of scientists within different disciplinary areas and attracts more researchers to devote themselves to this interesting research field.

Recent advances in organic thermally activated delayed fluorescence materials.

The design and characterization of thermally activated delayed fluorescence (TADF) materials for optoelectronic applications represents an active area of recent research in organoelectronics. Noble metal-free TADF molecules offer unique optical and electronic properties arising from the efficient transition and interconversion between the lowest singlet (S1) and triplet (T1) excited states. Their ability to harvest triplet excitons for fluorescence through facilitated reverse intersystem crossing (T1→S1) could directly impact their properties and performances, which is attractive for a wide variety of low-cost optoelectronic devices. TADF-based organic light-emitting diodes, oxygen, and temperature sensors show significantly upgraded device performances that are comparable to the ones of traditional rare-metal complexes. Here we present an overview of the quick development in TADF mechanisms, materials, and applications. Fundamental principles on design strategies of TADF materials and the common relationship between the molecular structures and optoelectronic properties for diverse research topics and a survey of recent progress in the development of TADF materials, with a particular emphasis on their different types of metal-organic complexes, D-A molecules, and fullerenes, are highlighted. The success in the breakthrough of the theoretical and technical challenges that arise in developing high-performance TADF materials may pave the way to shape the future of organoelectronics.

Thermally Activated Delayed Fluorescence Materials Towards the Breakthrough of Organoelectronics

We thank the University of St Andrews for support. EZ-C thanks the Leverhulme Trust for financial support (RPG-2016-047). and the EPSRC (EP/P010482/1) for financial support.

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Purely Organic Thermally Activated Delayed Fluorescence Materials for Organic Light-Emitting Diodes.

Ultrapure blue-fluorescent molecules based on thermally activated delayed fluorescence are developed. Organic light-emitting diode (OLED) devices employing the new emitters exhibit a deep blue emission at 467 nm with a full-width at half-maximum of 28 nm, CIE coordinates of (0.12, 0.13), and an internal quantum efficiency of ≈100%, which represent record-setting performance for blue OLED devices.

Ultrapure Blue Thermally Activated Delayed Fluorescence Molecules: Efficient HOMO–LUMO Separation by the Multiple Resonance Effect

A high-throughput virtual screening approach is used to select molecules with efficient, thermally activated delayed fluorescence. The good performance of several selected emitters in organic LED applications has also been confirmed experimentally.

Design of efficient molecular organic light-emitting diodes by a high-throughput virtual screening and experimental approach

H. Wang, L. Meng, Prof. Y. Wang, Prof. P. Wang Key Laboratory of Photochemical Conversion and Optoelectronic Materials Technical Institute of Physics and Chemistry Chinese Academy of Sciences Beijing 100190 , China E-mail: wangy@mail.ipc.ac.cn; wangpf@mail.ipc.ac.cn H. Wang, L. Meng University of Chinese Academy of Sciences Beijing 100049 , China Dr. Q. Peng, Prof. Y. Yi Beijing National Laboratory for Molecular Sciences Key Laboratory of Organic Solids Institute of Chemistry Chinese Academy of Sciences Beijing 100190 , China L. Xie College of Life Science and Technology Beijing University of Chemical Technology Beijing , China

Novel Thermally Activated Delayed Fluorescence Materials–Thioxanthone Derivatives and Their Applications for Highly Efficient OLEDs

Carbon nano-dots were synthesized by a hydrothermal method and integrated into the poly(vinyl alcohol) matrix as charge carrier trapping centers for nonvolatile memory devices. The devices with the configuration of ITO/carbon nano-dots-PVA/Ag exhibited bistable electrical switching at low voltage, long retention time and excellent reading stability.

Nonvolatile memory devices based on carbon nano-dot doped poly(vinyl alcohol) composites with low operation voltage and high ON/OFF ratio

Efficient and selective capture of uranium by polyethyleneimine-modified chitosan composite microspheres from radioactive nuclear waste.

Efficient Uranium Electrochemical Deposition with a Functional Phytic Acid-Doped Polyaniline/Graphite Sheet Electrode by Adsorption-electrodeposition Strategy

Lisha Xie

Papers

Novel Thermally Activated Delayed Fluorescence Materials–Thioxanthone Derivatives and Their Applications for Highly Efficient OLEDs

Nonvolatile memory devices based on carbon nano-dot doped poly(vinyl alcohol) composites with low operation voltage and high ON/OFF ratio

Efficient and selective capture of uranium by polyethyleneimine-modified chitosan composite microspheres from radioactive nuclear waste.

Efficient Uranium Electrochemical Deposition with a Functional Phytic Acid-Doped Polyaniline/Graphite Sheet Electrode by Adsorption-electrodeposition Strategy

Superior adsorption of Re(VII) by anionic imprinted chitosan-silica composite: Adsorption performance, selectivity and mechanism study