Regulating Spatial Configuration in Donor‐π‐Acceptor for through‐Space Exciton Transfer: Concentration‐Independent Emitter for OLEDs DOI Open Access
Nisha Yadav, Upasana Deori, Arun K. Manna

et al.

Advanced Optical Materials, Journal Year: 2024, Volume and Issue: unknown

Published: Dec. 26, 2024

Abstract Thermally activated delayed fluorescence (TADF) emitters have garnered much attention due to 100% exciton utilization and toxic metal‐free design but often experience concentration‐quenching, requiring dispersion into the host matrix. Developing that maintain consistent performance emission wavelength irrespective of concentration remains a significant challenge. Herein, two TADF (2BPy‐ p TC 2BPy‐ o TC) are designed synthesized. The nature energetics lowest excited singlet ( S 1 ) triplet T along with extent through‐bond transfer (TBET) through‐space (TSET) unveiled using reliable quantum‐chemical calculations. While exhibits pre‐dominantly TBET, greater TSET is found in TC. Both show low singlet‐triplet energy gap ΔE ST ), 0.21 eV for 0.02 For TC, increasing emitter from 5 100 wt.% causes bathochromic shift electroluminescence (EL) peak (467 495 nm) drop maximum external quantum efficiency EQE max 12.0% 5.5%. In contrast, maintains EL maxima 500 nm (24.0% – 27.2%) while concentration, acting as universal both doped non‐doped OLEDs eliminating need tedious co‐deposition.

Language: Английский

Multi‐π‐Stacked Through‐Space Charge‐Transfer Emitters with Accelerated Radiative Decay for High‐Efficiency Organic Light‐Emitting Diodes with Suppressed Efficiency Roll‐Offs DOI Open Access
Yongjun Song, Ke Zhang, Yibo Li

et al.

Advanced Functional Materials, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 7, 2025

Abstract Through‐space charge‐transfer (TSCT) thermally‐activated delayed fluorescence (TADF) emitters have been extensively explored for organic light‐emitting diodes (OLEDs), but their low radiative decay rates ( k r,s ) remained a formidable obstacle to enhancement of luminescent efficiency (Ф PL and suppression roll‐off the OLED. Here, multi‐π‐stacked TSCT‐TADF with accelerated are developed 3D [fixed acceptor]/donor/[fixed acceptor] structure formed on two individual fluorene bridges. Single‐crystal structures theoretical calculations reveal cis or trans ‐configurations acceptors around central donor double TSCT channels in emitter. In doped films, show green‐blue TADF high up 1.1 × 10 7 s −1 near‐unity Ф , which notably improved compared single‐π‐stacked analog = 2.1 6 0.89). OLEDs based external quantum efficiencies (EQEs) 26.2% EQEs at 1000 cd m −2 (EQE remain 23.4%, superior over device max /EQE 20%/15.6%). A narrowband blue‐green OLED one emitter as sensitizer shows EQE 37.6%/27.7%. The work demonstrates great potential enhancing high‐efficiency roll‐offs.

Language: Английский

Citations

1
Simultaneously Improving Radiative Decay and Reverse Intersystem Crossing in Space‐Confined Through‐Space Charge‐Transfer (TSCT) Emitter by Strong Intermolecular TSCT Enabled by a Planar Donor DOI
Yongjun Song, Ke Zhang,

Pingping Wang

et al.

Advanced Functional Materials, Journal Year: 2024, Volume and Issue: 35(1)

Published: Sept. 20, 2024

Abstract Simultaneously improving radiative decay and reverse intersystem crossing (RISC) of through‐space charge‐transfer (TSCT) thermally‐activated delayed fluorescence (TADF) emitters has remained a challenge. Here, space‐confined TSCT‐TADF are developed with planar indolo[3,2,1‐ kl ]phenoxazine donor, spiro‐carbon‐fixed benzophenone acceptor, fluorene (for 1 ) or xanthene 2 bridge. Close, cofacial donor/acceptor alignments efficient intramolecular TSCT have been observed for both emitters. Intriguingly, emitter exhibits an intermolecular interaction as strong the one, which opens TSCT, rate ( k r,s to same level featuring much stronger interaction. The also largely enhances RISC ). In 20 wt.% doped films, show green TADF high / at 1.1 × 10 7 s −1 /1.3 6 1.2 /7.7 5 , respectively. Organic light–emitting diodes (OLEDs) using external quantum efficiencies (EQEs) up 27.5% low‐efficiency roll‐offs. Hyperfluorescent OLEDs sensitizers afford narrowband blue‐green emission EQEs 30.6% suppressed efficiency work reveals that strengthening is promising avenue simultaneously improve r,s, high‐performance OLEDs.

Language: Английский

Citations

5
Enhancing Electroluminescence Performance of Ultra-Deep-Blue Through-Space Charge Transfer Emitters with CIEy ≈ 0.05 Via Methyl-modification DOI Creative Commons
Quanwei Li,

Haisong Zhao,

Jinyang Zhao

et al.

Chemical Science, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 1, 2025

A methyl-modification strategy is proposed to enhance the ICT and RISC processes of ultra-deep-blue through-space charge transfer emitters. The prepared emitter 3MeCz-BO achieves a high EQE max 10.1% with CIE coordinates (0.151, 0.051).

Language: Английский

Citations

0
Synergetic Multiple Charge‐Transfer Excited States for Anti‐Quenching and Rapid Spin‐Flip Multi‐Resonance Thermally Activated Delayed Fluorescence Emitter DOI Open Access

Lixiao Guo,

Weibo Cui,

Linjie Li

et al.

Advanced Materials, Journal Year: 2025, Volume and Issue: unknown

Published: March 29, 2025

The development of multiple resonances thermally activated delayed fluorescence (MR-TADF) emitters exhibiting high efficiency, narrowband emission, rapid reverse intersystem crossing rate (kRISC), and suppressed concentration quenching simultaneously is great significance yet a formidable challenge. Herein, an effective strategy presented to realize the above target by synergizing charge-transfer excited states, including short-range charge transfer (SRCT), through-bond (TBCT), through-space (TSCT). proof-of-concept emitter 4tCz2B exhibits bright green emission with narrow full width at half maximum (FWHM) 21 nm (0.10 eV) in solution, photoluminescence quantum yield 97%, fast kRISC 7.8 × 105 s-1 significantly film state. As result, sensitizer-free organic light-emitting diodes (OLEDs) achieve external efficiencies (EQEmaxS) over 34.5% together unaltered peak 508 FWHM 26 doping concentrations ranging from 3 20 wt.%. Even ratio 50 wt.%, EQEmax still as 25.5%. More importantly, non-sensitized devices exhibit reduced efficiency roll-offs, minimum value 13.4% brightness 1000 cd m-2.

Language: Английский

Citations

0
Efficiency Boost in Through Space Charge Transfer Emitters: Insights from Spiro Lateral Rocking Confinement DOI
Ruihong Liu,

Meng‐Tian Li,

Yue‐Jian Yang

et al.

Advanced Materials, Journal Year: 2024, Volume and Issue: unknown

Published: Dec. 12, 2024

Intramolecular through-space charge-transfer (TSCT) excited states have emerged as promising candidates for thermally activated delayed fluorescence (TADF) emitters. This study addresses the challenges in tuning state dynamics through conformational engineering, which significantly impacts exciton utilization. An effective strategy is presented to enhance performance of TSCT-TADF molecules by restricting lateral rocking spiro unit via immobilizing groups, indirectly adjusts conformations donor and acceptor subunits. approach successfully illustrated with two emitters, 8PhDM-B 8PyDM-B, featuring sterical aryl phenyl pyridine substitutions at C8 site a rigid spiro-fluorene bridge. Organic light-emitting diodes (OLEDs) utilizing these emitters demonstrated impressive maximum external quantum efficiencies 33.1% 31.0%, respectively. The findings underscore importance confined refining dynamics, thereby providing valuable insights design highly efficient OLED

Language: Английский

Citations

2
Robust Sandwich‐Structured Thermally Activated Delayed Fluorescence Molecules Utilizing 11,12‐Dihydroindolo[2,3‐a]carbazole as Bridge DOI Open Access
Lan Xia, Jiajie Zeng,

Jinke Chen

et al.

Angewandte Chemie, Journal Year: 2024, Volume and Issue: 137(1)

Published: Aug. 29, 2024

Abstract Constructing folded molecular structures is emerging as a promising strategy to develop efficient thermally activated delayed fluorescence (TADF) materials. Most TADF materials have V‐shaped configurations formed by donors and acceptors linked on carbazole or fluorene bridges. In this work, facile design proposed for exploring sandwich‐structured molecules, series of novel robust with regular U‐shaped sandwich conformations are constructed using 11,12‐dihydroindolo[2,3‐a]carbazole bridge, xanthone acceptor, dibenzothiophene, dibenzofuran, 9‐phenylcarbazole indolo[3,2,1‐JK]carbazole donors. They hold outstanding thermal stability ultrahigh decomposition temperatures (556–563 °C), exhibit fast excellent photoluminescence quantum efficiencies (86 %–97 %). The close stacking acceptor results in rigidified through‐space interaction, which conducive suppressing intramolecular motion reducing reorganized excited‐state energy. organic light‐emitting diodes (OLEDs) them emitters electroluminescence performances, maximum external up 30.6 %, leading value the OLEDs based emitters. These demonstrate employing bridge planar construct applicable.

Language: Английский

Citations

1
Robust Sandwich‐Structured Thermally Activated Delayed Fluorescence Molecules Utilizing 11,12‐Dihydroindolo[2,3‐a]carbazole as Bridge DOI
Lan Xia, Jiajie Zeng,

Jinke Chen

et al.

Angewandte Chemie International Edition, Journal Year: 2024, Volume and Issue: 64(1)

Published: Aug. 29, 2024

Constructing folded molecular structures is emerging as a promising strategy to develop efficient thermally activated delayed fluorescence (TADF) materials. Most TADF materials have V-shaped configurations formed by donors and acceptors linked on carbazole or fluorene bridges. In this work, facile design proposed for exploring sandwich-structured molecules, series of novel robust with regular U-shaped sandwich conformations are constructed using 11,12-dihydroindolo[2,3-a]carbazole bridge, xanthone acceptor, dibenzothiophene, dibenzofuran, 9-phenylcarbazole indolo[3,2,1-JK]carbazole donors. They hold outstanding thermal stability ultrahigh decomposition temperatures (556-563 °C), exhibit fast excellent photoluminescence quantum efficiencies (86 %-97 %). The close stacking acceptor results in rigidified through-space interaction, which conducive suppressing intramolecular motion reducing reorganized excited-state energy. organic light-emitting diodes (OLEDs) them emitters electroluminescence performances, maximum external up 30.6 %, leading value the OLEDs based emitters. These demonstrate employing bridge planar construct applicable.

Language: Английский

Citations

0
Regulating Spatial Configuration in Donor‐π‐Acceptor for through‐Space Exciton Transfer: Concentration‐Independent Emitter for OLEDs DOI Open Access
Nisha Yadav, Upasana Deori, Arun K. Manna

et al.

Advanced Optical Materials, Journal Year: 2024, Volume and Issue: unknown

Published: Dec. 26, 2024

Abstract Thermally activated delayed fluorescence (TADF) emitters have garnered much attention due to 100% exciton utilization and toxic metal‐free design but often experience concentration‐quenching, requiring dispersion into the host matrix. Developing that maintain consistent performance emission wavelength irrespective of concentration remains a significant challenge. Herein, two TADF (2BPy‐ p TC 2BPy‐ o TC) are designed synthesized. The nature energetics lowest excited singlet ( S 1 ) triplet T along with extent through‐bond transfer (TBET) through‐space (TSET) unveiled using reliable quantum‐chemical calculations. While exhibits pre‐dominantly TBET, greater TSET is found in TC. Both show low singlet‐triplet energy gap ΔE ST ), 0.21 eV for 0.02 For TC, increasing emitter from 5 100 wt.% causes bathochromic shift electroluminescence (EL) peak (467 495 nm) drop maximum external quantum efficiency EQE max 12.0% 5.5%. In contrast, maintains EL maxima 500 nm (24.0% – 27.2%) while concentration, acting as universal both doped non‐doped OLEDs eliminating need tedious co‐deposition.

Language: Английский

Citations

0