Triphenylamine disubstituted naphthalene diimide: elucidation of excited states involved in TADF and application in near-infrared organic light emitting diodes

Abstract

A new TADF emitter is presented showing near-infrared efficient emission.

Red‐Emitting Delayed Fluorescence and Room Temperature Phosphorescence from Core‐Substituted Naphthalene Diimides

“…However, unlike CzPhNDI , this phosphorescence band neither originates from carbazole (donor) or NDI (acceptor) components (Figure S12b, Supporting Information). Similar phosphorescence behaviour at low temperatures has been recently shown in donor–acceptor cNDI derivatives, wherein certain conformations of the molecule lead to enhanced conjugation between the donor (triphenyl amine) and acceptor sub‐units (NDI) resulting in new locally excited triplet state . In addition, gradual decrease in the lifetime on increasing the temperature (Figure f) reiterates (3.1 ms at 15 K to 80.5 μs at 300 K, λ exc.…”

A Simple and Strong Electron‐Deficient 5,6‐Dicyano[2,1,3]benzothiadiazole‐Cored Donor‐Acceptor‐Donor Compound for Efficient Near Infrared Thermally Activated Delayed Fluorescence

“…The NIR device turned on at a bias of 4.0 V (at radiance of 10 mW Sr −1 m −2 ) and emitted with a maximum radiance as high as 10020 mW Sr −1 m −2 and a maximum EQE of 6.57% as illustrated in Figure b‐ ‐ c and summarized in Table . This result is among the best EL performance for pure organic NIR fluorescence emitters with emission peak over 700 nm reported to date (Figure d) . Besides, the efficiency roll‐off of this NIR EL device was relatively small.…”

“…In order to accomplish the D−A type NIR TADF emissive molecules, A unit with a strong electron‐accepting strength is essentially needed to pair with D unit, which is commonly used arylamine derivatives, forming an effectively strong D‐A system. Additionally, in contrast to the versatile choices for D units, possible A units are fairly limited such as acenaphtho[1,2‐b]pyrazine‐8,9‐dicarbonitrile (APDC), naphtho[2,3‐c][1,2,5]thiadiazole (NZ), quinoxaline‐6,7‐dicarbonitrile (QCN), 2,3‐dicyanopyrazino phenanthrene (DCPP), acenaphtho[1,2‐b]quinoxaline‐8,9‐dicarbonitrile (AQ), dibenzo[a,j]phenazine (DBPHZ), boron difluoridecurcuminoid and naphthalene diimide (NDI) . Therefore, new building blocks of strong electronic acceptor have attracted more and more attention in preparing deep red and NIR TADF emitters by coupling with different donors.…”

Recent Advancements in and the Future of Organic Emitters: TADF‐ and RTP‐Active Multifunctional Organic Materials

“…TADF emitters typically cover the green–yellow region, including 4CzIPN , DPTZ‐DBTO2 , [Cu I (POP)(tmbpy)][BF 4 ] , and TPA‐QXN(CN)2 , and there have been reports of efficient blue TADF systems, but their stability is limited . There are not many reports of orange‐to‐red TADF emitters and they are mainly based on anthraquinone spironaphthalenone ( DCPSO ), phenazine ( POZ‐DBPHZ and DPXZ‐BPPZ ), or naphthalenediimide ( TPA‐cNDI ) acceptors (Figure ). The problem with red TADF emitters is fluorescence quenching and the difficulty of distinguishing between the TTA and TADF mechanisms, owing to the small energy differences.…”