Deep Blue Emitter Based on Tris(triazolo)triazine Moiety with CIE_y < 0.08 for Highly Efficient Solution‐Processed Organic Light‐Emitting Diodes Via Molecular Strategy of “Hot Excitons”

Abstract

Realizing high efficiency deep blue emission with a Commission international de I'Eclairage (CIE) coordinate of CIEy < 0.08 is still a big challenge. In this contribution, three molecules, named TTT‐TPA‐R (R = H, OMe, tBu), using tris(triazolo)triazine (TTT) as the acceptor and triphenylamine derivatives (TPA‐R, R = H, OMe, and tBu) as the donor are prepared and characterized. All these emitters show deep/pure blue emission between 420 and 470 nm in the PMMA film, concomitant with the excellent emission efficiency of 80–100%. Both experimental and calculated methods demonstrate that these emitters exhibit a clearly hybridized local and charge‐transfer excited state and can harvest both singlet and triplet excitons via reverse intersystem crossing process from the high‐lying triplet to singlet states. Therefore, the solution processable deep blue organic light‐emitting diodes (OLEDs) achieve a maximum external quantum efficiency (EQEmax) of 10.5% which is the recorded value for the solution processable deep blue OLED based on the “hot exciton” mechanism. Using TTT‐TPA‐H as the host material, solution‐processed phosphorescent OLED based on PO‐01 presents the EQEmax of 20.2%. These results pave a novel avenue for designing highly efficient deep blue emitter in solution processable OLED.

An AIE-active acridine functionalized spiro[fluorene-9,9′-xanthene] luminophore with mechanoresponsive luminescence for anti-counterfeiting, information encryption and blue OLEDs

“…The solution was concentrated to 20 mL under reduced pressure, and then a large amount of solid precipitate SFX-Ad was obtained in a yield of 63% (3.6 g). 1 H NMR (600 MHz, CDCl 3 ) d = 7.98 (d, J = 7.8 Hz, 2H), 7.47 (dd, J = 12.0, 5.4 Hz, 4H), 7.43 (dd, J = 7.8, 1.2 Hz, 4H), 7.39 (dd, J = 7.8, 1.2 Hz, 4H), 7.29 (dd, J = 7.8, 1.8 Hz, 2H), 7.19 (dd, J = 8.4, 2.4 Hz, 2H), 6.88 (td, J = 7.8, 1.2 Hz, 4H), 6.79 (m, 6H), 6.74 (m, 4H), 6.38 (m, 4H), 6.06 (dd, J = 8.4, 1.2 Hz, 4H), 6.02 (dd, J = 8.4, 0.6 Hz, 4H), 1.65 (t, J = 5.4 Hz, 24H). 13…”

“…Luminescent materials have received significant attention in the past few decades due to their useful applications in diverse fields such as sensors, ion probes, organic light-emitting diodes (OLEDs), information security engineering, and biological imaging. [1][2][3][4][5][6][7] In this context, thousands of luminophores based on aromatic compounds have been developed. [8][9][10][11] However, mainly due to the strong p-p interactions, most of the traditional luminophores suffer badly from the aggregation-caused quenching (ACQ) effect, which limits their practical application in aggregates and the solid state.…”

Deep-blue emission and thermally activated delayed fluorescence via Dimroth rearrangement of tris(triazolo)triazines

“…2,24,25 In recent years [1,2,4]-triazolo-[1,3,5]-triazine (TTT) has attracted significant attention in the realm of blue-emitting TADF materials due to their weak electron-withdrawing ability. [26][27][28][29][30] The synthesis for this unique heterocyclic motif features cyclization of aryl tetrazoles onto cyanuric chloride under basic conditions. 31,32 To date, several derivatives of TTT-based TADF materials have been successfully synthesized with respectable device performance.…”

Referential tuning strategy for high-lying triplet energy level setting in OLED emitter with hot-exciton characteristics

“…(1) A large energy gap between T 2 and T 1 states (DE T2T1 ) suppresses the internal conversion of a high-lying T 2 exciton to the T 1 platform (T 2 -T 1 ). [15][16][17] (2) A small energy splitting (DE st ) and large spin-orbit coupling (SOC) between excited S 1 and T 2 states are very beneficial for accelerating singlet exciton conversion from a triplet exciton according to perturbation theory. 18 Among these factors, a larger DE T2T1 is of special importance to help boost the radiative EUE in ''hot-exciton'' emitting layers.…”

“…(1) A large energy gap between T 2 and T 1 states (Δ E T2T1 ) suppresses the internal conversion of a high-lying T 2 exciton to the T 1 platform (T 2 → T 1 ). 15–17…”