An indolo[3,2,1-jk]carbazole-fused multiple resonance-induced thermally activated delayed fluorescence emitter for an efficient narrowband OLED

Abstract

By inserting tricoordinate B atom into an indolo[3,2,1-jk]carbazole precursor, an efficient fused multiple resonance induced thermally activated delayed fluorescence emitter were prepared, which exhibits a narrowband emission and a considerable...

Recent progress and prospects of fluorescent materials based on narrow emission

“…14f) by further rigidifying the NBNP . 108 Similar to NBNP , LTCz-BN exhibited narrowband green emission at 497 nm with an FWHM of 27 nm and a small Δ E ST of 0.10 eV in toluene. The high PLQY value of LTCz-BN was 93% in 5 wt% doped mCBP films.…”

“…14 (a-j) Chemical structures of emitters discussed in Section 3.2.3. [103][104][105][106][107][108][109][110][111]113 (EQE max = 6.1%). The PhDMAC-BN-based OELD exhibited an EQE max of 27.2%, a l EL of 480 nm, an FWHM of 34 nm, and CIE color coordinates of (0.105, 0.264), and the EQE max was further improved to 33.9% when 3tPAB was employed as a sensitizer for PhDMAC-BN.…”

Recent progress in multi-resonance thermally activated delayed fluorescence emitters with an efficient reverse intersystem crossing process

“…In particular, OLEDs based on TCz-VTCzBN displayed ultra-pure green emission with CIE coordinates of (0.22, 0.71). Besides, our group introduced a tricoordinate B atom into the indolo[3,2,1- jk ]carbazole (ICz) fused MR skeleton to achieve an MR fluorophore to an MR-TADF emitter conversion, realizing a rigidly green B/N framework based MR-TADF emitter ( LTCz-BN ), 60 showing a small FWHM of 27 nm and a high PLQY of 93%, as well as a high k RISC of 8.3 × 10 5 s −1 . Consequently, the LTCz-BN -based OLED simultaneously exhibited an EQE max value of 27.2% with a small FWHM of 34 nm, and a much suppressed efficiency roll-off, whose value still reached 25.4% at 3000 cd m −2 .…”

Double charge transfer processes enable a green multiple resonance-induced thermally activated delayed fluorescence emitter for an efficient narrowband OLED

“…7–21 However, MR-TADF compounds generally exhibit a large singlet–triplet energy gap (Δ E ST ) and small rate of reverse intersystem crossing ( k RISC ) owing to a large frontier molecular orbital (FMO) overlap integral compared with those of through-bond (TB) CT 22 and through-space (TS) CT 23 TADF molecules. In order to improve the k RISC values of MR-TADF emitters, strategies such as heavy atom integration, 24 heavy metal introduction, 25 and π-conjugation extension 26 have been successfully proposed. Notably, the structural relaxation of MR-TADF molecules in the ground and excited states will increase, leading to broadening of the full width at half maximum (FWHM) due to the introduction of large deformation atoms such as a S atom.…”