Sequential Multiple Borylation Toward an Ultrapure Green Thermally Activated Delayed Fluorescence Material

Abstract

Multiple-resonance thermally activated delayed fluorescence (MR-TADF) emitters have emerged as an important component of organic light-emitting diodes (OLEDs) because of their narrowband emission and high exciton utilization efficiency. However, the chemical space of MR-TADF emitters remains mostly unexplored because of the lack of suitable synthetic protocols. Herein, we demonstrate a sequential multiple borylation reaction that provides new synthetically accessible chemical space. ω-DABNA, the proof-of-concept material, exhibited narrowband green TADF with a full width at half-maximum of 22 nm and a small singlet−triplet energy gap of 13 meV. The OLED employing it as an emitter exhibited electroluminescence at 512 nm, with Commission International de l'E ́clairage coordinates of (0.13, 0.73) and a high external quantum efficiency (EQE) of 31.1%. Moreover, the device showed minimum efficiency roll-off, with an EQE of 29.4% at 1000 cd m −2 .

Recent progress and prospects of fluorescent materials based on narrow emission

“…6p), with five [4]helicene substructures and a highly twisted structure. 73 The emitter exhibited narrowband green emission at 509 nm with an FWHM of 22 nm and a high PLQY of 87% when doped in PMMA. It is noteworthy that the Δ E ST of ω-DABNA is only 0.013 eV.…”

Recent advances and prospects for organoboron-based thermally activated delayed fluorescence emitters

“…Moreover, the device showed minimum efficiency roll-off, with an EQE of 29.4% at 1000 cd m −2 . 121 Wang et al reported a ternary B–O–N embedded PAH, 215 , by adopting the para boron–π–boron and para oxygen–π–oxygen strategy. 215 presented a vivid green emission with a high PLQY of 96% and an extremely narrow FWHM of 19 nm/0.09 eV, which surpassed all previously reported green TADF emitters to date.…”

Precisely regulating the double-boron-based multi-resonance framework towards pure-red emitters: high-performance OLEDs with CIE coordinates fully satisfying the BT. 2020 standard

“…Compared to the widely-reported blue 11–14 and green 15–19 MR emitters with excellent color-purity that approaches the BT. 2020 standard, however, the development of pure-red MR emitters remains challenging.…”

“…Since the pioneer work by Hatakeyama et al, [3][4][5] a large number of highperformance BN-based MR emitters have been reported. [6][7][8][9][10] Compared to the widely-reported blue [11][12][13][14] and green [15][16][17][18][19] MR emitters with excellent color-purity that approaches the BT. 2020 standard, however, the development of pure-red MR emitters remains challenging.…”