CN‐Modified Imidazopyridine as a New Electron Accepting Unit of Thermally Activated Delayed Fluorescent Emitters

Abstract

Twoe fficient thermally activated delayed fluorescent (TADF) emitters were developed by utilizing CN-modified imidazopyridine as an acceptoru nit. The CN-modified imidazopyridine acceptorw as combined with either an acridine donoro rap henoxazine donor through ap henyll inker to produce two TADF emitters, Ac-CNImPy and PXZ-CNImPy. The acridine-based Ac-CNImPy emitter exhibited sky-blue emission with aC IE coordinate of (0.18, 0.38), whereast he phenoxazine-donor-based PXZ-CNImPy showed greenish-yellowe mission with aC IE coordinate of (0.32, 0.58). Ah igh photoluminescence quantum yield of 80 %w as observed for the PXZ-CNImPy emitter compared with 40 %f or the Ac-CNImPy emitter.O rganic light-emitting diodes basedo nt he PXZ-CNImPy emitter demonstrated highe xternal quantum efficiency of 17.0 %. Hence, the CN-modified imidazopyridine unit can be considered as au seful electron acceptorf or the futured esign of highly efficient TADF emitters.

Isomer engineering of dipyrido[3,2-a:3′,4′-c]phenazine-acceptor-based red thermally activated delayed fluorescent emitters

“…The red TADF-OLED doped with oDMAC-DPPZ exhibited a considerably higher EQE (13.4%) than the pDMAC-DPPZ-doped OLED (4.0%). Therefore, it was demonstrated that donor substitution at the ortho (11,12) position of the DPPZ acceptor is preferred to the para (10, 13) substitution in the design of highperformance long-wavelength TADF emitters.…”

“…Organic-emitter-based thermally activated delayed fluorescent (TADF)-OLEDs are considered competent alternatives to Ph-OLEDs, as internal quantum efficiencies of up to 100% are achievable in both cases. [7][8][9][10][11][12][13] Compared to precious-metalbased phosphorescent emitters, TADF emitters are inexpensive and allow for greater diversity in their design. Organic materials with a small singlet-triplet energy gap (DE ST ) are capable of converting non-radiative triplet excitons to radiative singlet excitons via a reverse intersystem crossing (RISC) process.…”

Design of Imidazo[1,2-a]pyridine-Based Donor–Acceptor Chromophores through a Multicomponent Approach

“…H NMR (500 MHz, CDCl3) δ [ppm] = 9.83 (d, J = 0.7 Hz, 2H), 8.49 (d,J = 7.9 Hz,1H,CHAr),2H,CHAr),8.34 (d,J = 2.0 Hz,1H,CHAr),8.31 (d,J = 7.8Hz,2H,CHAr),2H,CHAr),7.82 (dd,J = 7.9 Hz,1.8 Hz,1H,CHAr),7.78 (t,J = 7.8 Hz,1H,CHAr). FAB-MS m/z (%): 341 (11), 307 (22), 289 (13), 219 (9), 191 (9), 167 (9), 155 (30), 154 (100), 153 (10), 152 (10), 149 (9), 147 (13), 139 (17), 138 (37), 137 (65), 136 (71), 135 (9), 131 (10), 124 (11), 121 (11), 120 (12), 119 (13), 117 (9), 115 (10), 107 (24), 105 (13), 97 (11), 95 (13), 91 (23), 90 (10), 89 (18). This article is protected by copyright.…”

“…, 291 (13), 290 (5), 289 (30), 288 (5), 287 ( 16), 154 (6), 105 (6), 95 (7), 91 (6). 8), 418 (9), 417 (7), 337 (7), 310 ( 6), 233 (6), 154 (10), 136 (7). This article is protected by copyright.…”

“…9 In 2020, Lee et al reported on the first series of TADF-emitters containing the imidazopyridine motif. 10 Nitrile groups were grafted onto the scaffold to enhance their electron-withdrawing properties and combined it as an acceptor with two different donors. As the secondary amino substituent originating from the isonitrile employed in the GBB-3CR increases the electron density of the imidazopyridine, we expected that this moiety would be very well suited as a donor rather than an acceptor.…”