Rong-Huei Yi

Selenium-atom engineering of a carbonyl-embedded multiple-resonance TADF (MR-TADF) framework dramatically enhances spin-orbit coupling, boosting the intersystem crossing quantum yield to near-unity (Φ _ISC = 0.97) and achieving an exceptionally high k _ISC/k _RISC ratio of 9.76 × 10⁴. This maximizes triplet exciton flux for efficient photoredox initiation, enabling ultrafast, high-resolution DLP 3D printing under low-intensity light in ambient air.

ABSTRACT

The photoinitiating system is a decisive factor governing the speed, resolution, and operational robustness of digital light processing (DLP) 3D printing. However, most existing systems rely on inert atmospheres, high irradiation intensities, or prolonged exposure times, severely limiting printing efficiency and practical applicability. Here we report a molecular design paradigm that fundamentally redefines the functional role of multiple-resonance thermally activated delayed fluorescence (MR-TADF) materials, transforming them from efficient light emitters into highly active triplet photocatalysts through selenium-atom engineering. By integrating carbonyl-assisted n–π*/π–π* state coupling with selenium-induced spin-orbit enhancement, the resulting photocatalyst QPSO achieves a near-unity intersystem crossing quantum yield together with an exceptionally large forward-to-reverse intersystem crossing rate constant ratio, thus efficiently channeling exciton flux into long-lived, redox-active triplet states. When combined with a hypervalent iodonium co-initiator, this system enables rapid photopolymerization in ambient air using low-intensity blue light. As a result, single-layer curing is completed within only 1.5–2 s across a broad thickness range, affording a printing resolution down to 10 µm and a record-high build speed of up to 72 cm h⁻¹ at 400 µm layer thickness. The platform supports the fabrication of complex hierarchical architectures while exhibiting excellent biocompatibility.

The through-space charge transfer (TSCT) emitter featuring efficient blue emission and rapid reverse intersystem crossing (RISC) process has been developed by employing a fully planarized donor. Organic light-emitting diodes applying the material as emitter and sensitizer show maximum external quantum efficiencies (EQEs) of 34.0% and 35.8%, respectively.

ABSTRACT

Through-space charge transfer (TSCT) emitters featuring spatially separated donor-acceptor architecture offer a promising strategy for designing thermally activated delayed fluorescence materials. However, developing high-performance blue TSCT emitter remains challenging due to the intrinsic trade-off between a wide bandgap and sufficient spatial electronic interactions. Herein, a fully planarized donor, in favor of strengthening spatial interactions and suppressing non-radiative decay, is proposed to construct blue TSCT emitter. The resulting emitter exhibits an emission peak of 467 nm, a high photoluminescence quantum yield of 98% and a large reverse intersystem crossing (RISC) rate of 1.8×10⁶ s⁻¹. Organic light-emitting diodes based on the emitter achieve a maximum external quantum efficiency (EQE_max) of 34.0% with Commission Internationale de L'Eclairage (CIE) coordinates of (0.16, 0.29) and a maximum luminance of 21560 cd m⁻², which, to the best of our knowledge, represents the state-of-the-art performances for blue TSCT emitters. Furthermore, hyperfluorescent devices employing the emitter as sensitizer demonstrate a high EQE_max of 35.8% with a narrow full width at half maximum of 20 nm and CIE coordinates of (0.12, 0.14). This work demonstrates the critical importance of the fully planarized donor for developing high-efficiency blue TSCT emitter.

Molecular recognition guest binding can comprehensively modulate photoinduced charge-transfer dynamics in the cyclophane host, including charge separation and recombination, via coherent superexchange and incoherent hopping. Unlike covalent donor–bridge–acceptor systems, this supramolecular approach avoids tedious syntheses and offers precise tuning of charge-transfer properties, opening routes to next-generation light-harvesting materials.

ABSTRACT

Photoinduced charge transfer (CT) underpins photosynthesis and solar energy conversion technologies. However, achieving comprehensive control over CT in traditional covalent donor−bridge−acceptor (D−B−A) systems remains challenging, hindered by tedious organic synthesis and limited tunability. In this investigation, we harness molecular recognition to regulate photoinduced CT—including charge separation and recombination—leveraging its facile preparation and dynamic reversibility. By integrating guest molecules with a wide range of frontier orbital energies into a rigid cyclophane host (DAPPTTzBox⁴⁺ ), which features directional photoinduced intramolecular CT through cofacially stacked chromophores, we achieve comprehensive modulation of CT within well-defined supramolecular complexes. This modulation spans mechanisms from tunneling to incoherent hopping. Notably, molecular recognition accelerates charge separation in DAPPTTzBox⁴⁺ by 5.9- to 230-fold, shifting from single-step superexchange to multistep incoherent charge shift, while charge recombination rates are decreased (from 1.3‑ to 2.8‑fold) in superexchange systems. Additionally, guest-induced charge trapping was also successfully demonstrated. This research exemplifies a fresh strategy for manipulating CT dynamics via noncovalent interactions, opening new avenues for the design of advanced artificial light-harvesting materials.

Triphenylene-involved π-extension, combining with phenyl-blocking, enables a stable MR-TADF emitter, and the resulting top-emitting OLED realizes EQE approaching 60% with BT.2020 green gamut and long lifetime.

ABSTRACT

The realization of ultrahigh definition displays necessitates pure-green organic light-emitting diodes (OLEDs) with simultaneously exceptional efficiency, high color purity, and long-term operational stability. Herein, we develop a series of pure-green multi-resonance thermally activated delayed fluorescence (MR-TADF) emitters based on the boron/nitrogen-embedded polycyclic aromatic hydrocarbon (BN-PAH), designed through a rational moderate π-extension and peripheral phenyl blocking strategy. The molecular designs afford narrowband pure-green emission with a full-width at half-maximum (FWHM) of nearly 20 nm and high photoluminescence quantum yields (Φ _PLs, up to 95%). By systematically blocking the redox-active positions with phenyl groups, the emitters exhibit significantly enhanced electrochemical and photochemical stability. In bottom-emitting OLEDs, the optimized emitter BN-Tpl-Ph achieves a maximum external quantum efficiency (EQE_max) of 33.8% and long operational lifetime (LT80 = 4012 h at 1000 cd m⁻²). Notably, in a top-emitting OLED configuration, BN-Tpl-Ph delivers a pure-green emission with a Commission Internationale de l'Eclairage (CIE) y-coordinate of 0.78, a high EQE_max up to 59.2%, and an LT80 of 409 h at 5000 cd m⁻². This work reveals the effectiveness of molecular design strategies that combine moderate π-extension with peripheral phenyl blocking for developing high-performance pure-green MR-TADF emitters.

A dual-polarization strategy is developed to achieve spontaneous exciton dissociation while lowering E _b by introducing B←N bonds and triazine as the dual-polarization units, achieving a superhigh AQY of 25.84% at 420 nm and SCC up to 1.20% in pure water for H₂O₂ evolution.

Abstract

Severe exciton effect significantly hinders free-charge-involved water redox reactions, limiting the improvement of photocatalytic performance. Herein, a dual polarization strategy was proposed to achieve spontaneous exciton dissociation while lowering exciton binding energy by introducing B←N bonds and triazine as the dual-type polarization unit into the alkynyl-linked conjugated backbone. Dual-type polarization centers can induce spontaneous exciton dissociation (exciton activation energy <25 meV) to generate more free charges that participate in water oxidation reactions. Triazine as the second polarization unit, lowers the energy barrier of the H₂O oxidation reaction and serves as the active site of the O₂ reduction reaction to accelerate H₂O₂-evolution. The H₂O₂-evolution performance of the dual-polarization photocatalyst reaches up to 4261 µmol g⁻¹ h⁻¹ with a superb apparent quantum yield of 25.84% at 420 nm and solar-to-chemical energy conversion up to 1.20% in pure water, surpassing most of the H₂O₂-evolution organic photocatalysts ever reported. Furthermore, the dual-polarization photocatalyst exhibits strong universality in complex water bodies (lake water, river water, and seawater), while achieving higher H₂O₂-evolution performance than that in pure water.

Boosting triplet harvesting in N/C═O MR-TADF emitters unexpectedly induces rapid photodegradation under oxygen-free conditions. Spectroscopic studies reveal that triplet excited states trigger hydrogen-atom transfer from solvent to the carbonyl unit, driven by triplet energetics and hydrogen electrophilicity. This previously overlooked vulnerability appears general across related systems, underscoring the need to consider photochemical stability in molecular design.

ABSTRACT

Nitrogen/carbonyl (N/C═O) based multi-resonant thermally activated delayed fluorescence (MR-TADF) emitters are attractive due to their narrowband delayed emission. Here, four MR-TADF emitters were developed by sterically wrapping a tert-butylated DiKTa core. Through modulation of short-range and through-space charge transfer, triplet harvesting efficiency was boosted from 1% in tDiKTa to 52% in tDiKTa-GCz (k _RISC = 1.37 × 10⁶ s⁻¹) in degassed toluene. Surprisingly, however, these improvements were accompanied by rapid photodegradation, while that same degradation was not observed in toluene under air. Our studies revealed that triplet excited states trigger hydrogen-atom transfer (HAT) from the solvent to the carbonyl group of the emitter, leading to fast, irreversible chemical change. Moreover, this phenomenon was found to be general for several previously published MR-TADF compounds. Using natural population analysis and bond dissociation energies, we show that the electrophilicity of the donor hydrogen atom governs the observed reactivity. This work uncovers a previously unrecognized photochemical vulnerability in N/C═O MR-TADF systems, and suggests that researchers studying them must be aware of their sensitivity toward HAT-induced photodegradation. We also call for a careful re-examination of published data on these compounds, as even brief exposure to light was sufficient to cause observable degradation in certain solvents.

A new class of rigid chiral macrocycles, Acetal[6]arenes (Ac[6]), features a unique “chirality-on-annulus” design for robust guest capture. By forming charge-transfer (CT) complexes through outer-surface interactions, Ac[6] enables efficient chiral amplification and intense circularly polarized luminescence (CPL). These supramolecular materials demonstrate versatile solid-state utility, ranging from multicolor optical sensing to time-encoded encryption.

ABSTRACT

Acetal[6]arenes (Ac[6]) are introduced as a new class of rigid chiral macrocyclic arenes in which carbon-centered chirality is embedded in a trioxabicyclo[3.3.1]nonane motif at macrocyclic waist. Ac[6] efficiently forms charge-transfer (CT) complexes with electron-deficient aromatic guests in both solution and the solid state. Single-crystal x-ray diffraction reveals that guest molecules bind to the outer surface of Ac[6] through well-defined stacking interactions. In contrast, the corresponding acyclic bis-acetal precursors show no complexation behavior, indicating that the rigid macrocyclic topology suppresses ring-unit flipping and significantly enhances interfacial π–π interactions. The resulting solid-state complexes exhibit dual emission at CT band (prompt fluorescence and TADF). Notably, complexes derived from enantiopure Ac[6] display intense circular dichroism (CD) and circularly polarized luminescence (CPL). The associated dissymmetry factors (g_abs and g_lum ) even exceed intrinsic Ac[6] values, indicating highly efficient chiral transfer. Ac[6] shows robust guest-capture capability, forming CT complexes not only via solution co-crystallization but also through simple physical mixing and even gas-phase guest uptake. By exploiting time-dependent capture kinetics and multicolor optoelectronic properties, we developed applications for optical sensing and time-encoded encryption. These results establish macrocyclization of rigid chirality-on-annulus units as a powerful strategy for creating functional supramolecular CT materials with emergent chiroptical and optoelectronic properties.

A C ₂-symmetric chiral carbazole–triphenyltriazine emitter (DC-TRZ) shows deep-blue emission at 433 nm with 79% efficiency. CP-OLEDs using (R)/(S)-DC-TRZ give CIE (0.14, 0.07), EQE_max 4.58%, and record |g _lum| up to 2.7 × 10⁻², with opposite CPL signs and excellent device stability under operation.

ABSTRACT

Deep blue circularly polarized organic light-emitting diodes (CP-OLEDs) remain scarce due to the stringent requirement of simultaneously achieving a wide bandgap and strong chiroptical activity. Herein, we report DC-TRZ, a C ₂-symmetric chiral emitter comprising a dimeric carbazole donor and a triphenyltriazine acceptor, which exhibits deep-blue emission at 433 nm with the high emission efficiency of up to 79%. Its enantiopure (R)- and (S)-isomers display pronounced Cotton effects and distinct circularly polarized luminescence (CPL). Notably, CP-OLEDs based on (R)- and (S)-DC-TRZ deliver deep-blue electroluminescence with Commission Internationale de L'Eclairage (CIE) coordinates of (0.14, 0.07), achieving a maximum external quantum efficiency of 4.58% and record-high luminescence dissymmetry factors of +2.7 × 10⁻² and −2.2 × 10⁻², respectively, representing the highest values reported to date for blue CP-OLEDs employing small organic molecules. These results demonstrate that DC-TRZ functions as an efficient deep-blue chiral emitter and highlights C ₂-symmetric axial chirality as a promising molecular design strategy for high-performance CP-OLED materials.

Robust folded thermally activated delayed fluorescence molecules based on through-space charge transfer mechanism are developed, which enjoy ultrahigh thermal stability and hold balanced bipolar transport ability. They behavior efficient electroluminescence property and function as promising sensitizers for multi-resonance emitters for fabricating high-performance hyperfluorescence OLEDs.

ABSTRACT

Folded thermally activated delayed fluorescence (TADF) molecules based on through-space charge transfer (TSCT) have aroused increasing interest, but the electroluminescence (EL) efficiencies of most folded TADF molecules are still inferior, and their application as sensitizers for multi-resonance TADF (MR-TADF) emitters remains barely explored. Herein, two novel isomeric folded TADF molecules, f-TRZ-1 and f-TRZ-2, are constructed by using 2,4,6-triphenyl-1,3,5-triazine (TRZ) as acceptor, 9-phenylcarbazole (PC) as donor, and 11,12-dihydroindolo[2,3-a]carbazole (HIC) as bridge. They exhibit regular intramolecular packing structures with effective TSCT and enjoy ultrahigh thermal stability and balanced bipolar charge transport. Moreover, efficient organic light-emitting diodes (OLEDs) are fabricated using f-TRZ-1 and f-TRZ-2 as emitters, achieving maximum external quantum efficiencies (η _ext,max) of up to 28.9%. f-TRZ-1 and f-TRZ-2 can perform as efficient sensitizers for the green MR-TADF emitter tCzphB-Fl, and the prepared hyperfluorescence OLEDs exhibit outstanding EL performances, with improved η _ext,maxs of up to 37.8% and reduced efficiency roll-offs. This work demonstrates the promising potential of these folded TADF molecules as emitters and sensitizers for the fabrication of high-performance OLEDs.

Stepwise molecular engineering is developed to enhance rigidity and symmetry, thereby narrowing the full-width at half maximum (FWHM), improving the photoluminescence quantum yield and accelerating the reverse intersystem crossing rate, ultimately yielding deep-blue OLED with an FWHM of 19 nm and a maximum external quantum efficiency of 24.2%.

ABSTRACT

Developing high-color-purity deep-blue emitters that meet the BT.2020 standard remains a critical challenge in organic light-emitting diodes (OLEDs). Herein, a stepwise molecular engineering strategy for simultaneously accelerating reverse intersystem crossing rate (k _RISC) and narrowing full-width at half maxima (FWHM) is proposed for deep-blue materials. By sequentially enhancing molecular rigidity, strengthening resonant strength, and completing molecular symmetry, a deep-blue emitter (DBNDICz), constructed on modified diboron multiple-resonance scaffold, is developed with peak of 452 nm, ultra-narrow FWHM of 15 nm (0.08 eV) and k _RISC of 3.0 × 10⁵ s^{− 1}. The dominant υ _0-0 transition character of DBNDICz produces a Commission Internationale de I’Éclairage (CIE) coordinates of (0.144, 0.060). Moreover, the expanded conjugated skeleton facilitates horizontal dipole orientation of 93%, leading to a high maximum external quantum efficiency (EQE_max) of 24.2% in bottom-emitting OLEDs. Impressively, top-emitting OLED achieves a record-setting blue index of 514 cd A^{− 1} CIEy^{− 1} with CIE (0.146, 0.036) and EQE_max of 45.2%, establishing a benchmark for state-of-the-art deep-blue devices. Additionally, an operational lifetime (LT₅₀) of 154.2 h is achieved in an anthracene-based host. These results represent one of the best performances reported for deep-blue OLEDs with CIEy≤ 0.06, providing a robust design paradigm for high-performance narrowband deep-blue TADF emitters.

A triple long-range charge-transfer channel strategy is introduced to enhance spin-orbit coupling and accelerate reverse intersystem crossing in multi-resonance thermally activated delayed fluorescence emitters. The proof-of-concept emitter DABNA-CN-PXZ exhibits ultrapure narrowband deep-blue emission with markedly accelerated excited-state dynamics, achieving a CIE _y of 0.046 and a maximum external quantum efficiency of 24.4% in devices.

ABSTRACT

To accelerate the reverse intersystem crossing (RISC) process of multi-resonance thermally activated delayed fluorescence (MR-TADF) emitters, constructing hybridized long-range charge-transfer (LRCT) and short-range charge-transfer (SRCT) states within MR-TADF molecules is a promising strategy. However, the conventional hybrid LRCT-SRCT strategy proves less effective in enhancing the performance of deep-blue emitters. In this study, we propose a novel triple-LRCT-channel strategy to markedly enhance spin-orbit coupling (SOC) interactions in deep-blue LRCT/SRCT type TADF emitters. Based on the pronounced differentiation among the excited states enabled by this strategy, the proof-of-concept emitter DABNA-CN-PXZ exhibits multiple RISC channels, resulting in a tenfold faster RISC rate than its MR prototype. The corresponding device achieves a high maximum external quantum efficiency of 24.4% and a narrow FWHM of 24 nm, which ranks among the lowest reported for boron-nitrogen-based LRCT/SRCT type TADF emitters, arising from the judicious selection of substituents in DABNA-CN-PXZ that enables precise control over molecular rigidity and LRCT characteristics. These results demonstrate that DABNA-CN-PXZ is among the purest deep-blue LRCT/SRCT type TADF emitters, delivering excellent device performance under BT.2020-compliant conditions and thus validating the superiority of our molecular design strategy.

In this study, we report a topology-divergent one-pot synthetic strategy that enables the simultaneous construction of two structurally distinct boron-nitrogen (BN)-doped polycyclic aromatic hydrocarbon (PAH) emitters for narrowband OLEDs: a twisted helical tetra-boron doped emitter (4BN) with an FWHM of 13 nm and a quasi-planar tri-boron doped emitter (3BN) with an FWHM of 18 nm.

ABSTRACT

Heteroatom-doped polycyclic aromatic hydrocarbons (PAHs) with special topological structures have garnered significant attention owing to the effective regulation of photophysical properties of emitters at the molecular level. Herein, we report the design and one-pot synthesis of two heteroatom-doped PAHs, namely 4BN with a twisted helical configuration and 3BN with a quasi-planar configuration. Systematic structure-property investigations reveal that molecular topology plays a decisive role in governing intrinsic electronic structures and intermolecular interactions. The quadruple-borylated 4BN with rigid PAH skeleton effectively suppresses structural relaxation and electron-vibrational coupling via manipulating the non-bonding characteristics, thereby affording ultra-narrowband emission. Consequently, for 4BN, the full widths at half maximum (FWHMs) as narrow as 13 nm in toluene solution and 14 nm in solution-processed electroluminescence device are achieved, representing the narrowest FWHM reported to date for OLEDs based on multiple resonance (MR) emitters. Furthermore, in TADF-assisted solution-processed device, the emission spectrum slightly broadens to 15 nm with a maximum external quantum efficiency (EQE_max) of 18.9%. In sharp contrast, the triple-borylated 3BN with quasi-planar geometry shows enhanced π-delocalization and stronger vibronic coupling, resulting in broader FWHM of 25 nm in TADF-assisted solution-processed devices with an EQE_max of 19.8%.

A streamlined 1,2-BN-fluoranthene embedding strategy has been developed to generate a series of narrowband emitters with emission bands spanning the visible to near-infrared region (429–703 nm). Notably, these emitters exhibit an exceptionally narrow full width at half maximum (FWHM) as low as 14 nm, along with a record-high external quantum efficiency (EQE) reaching 44.3%.

ABSTRACT

Developing a generalizable design principle that reconciles wide-range color tunability with intrinsically narrowband emission in polycyclic aromatic hydrocarbons (PAHs) remains a fundamental challenge in molecular optoelectronics. Herein, we combine the aromatic localization effect (ALE) with heteroatomic topology engineering to establish a versatile 1,2-BN-fluoranthene embedding strategy, implemented through a concise carbazole-assisted borylation. This approach furnishes a modular family of [B–N]₂PAHs whose emissions span the visible-to-near-infrared range (429–703 nm) while retaining exceptionally narrow full widths at half maximum (FWHM) down to 14 nm. Their chromaticities satisfy the stringent BT.2020 display standard, with selected derivatives even reaching the ultra-high-purity ProPhoto RGB gamut, establishing a viable platform for wide-color-gamut OLEDs. Representative pyrene- and perylene-based [B–N]₂PAHs display near-unity photoluminescence quantum yields (up to 99%) and ultrahigh horizontal transition dipole ratios (up to 98.0%), enabling outstanding electroluminescence performance. Devices based on these emitters exhibit emission peaks at 481 and 542 nm with narrow FWHMs of 19 and 29 nm, respectively and achieve maximum external quantum efficiencies (EQE_max) of 35.5% and 44.3%—the first fluorescent OLEDs to surpass the 40% EQE threshold. Importantly, 1,2-BN-embedded PAHs rival state-of-the-art 1,4-BN-based multiple-resonance (MR) emitters, while offering a substantially simpler, more general synthetic blueprint readily extendable to diverse PAH architectures.

This work establishes a facile strategy to fabricate multicolor, ultra-stable CPRTP films by covalently anchoring arylboronic acid chromophores onto nanostructured chitosan derived from shrimp shell waste via B─O bonds. According to the strategy, the resulting composite films exhibit multicolor right-handed CPRTP emissions, ultralong lifetimes, high dissymmetry factors, and harsh-environment stability, enabling advanced multilevel anti-counterfeiting.

Abstract

Developing circularly polarized room-temperature phosphorescent (CPRTP) materials from biomass holds great promise for chiral science and biophotonics. However, current luminescent materials face significant challenges, including color monotony in CPRTP emission and poor luminescence stability under humid and aqueous conditions. Here, a facile and versatile molecular engineering strategy to anchor arylboronic acid chromophores onto shrimp shell-derived nanostructured chitosan films via B─O covalent bonds is presented. Synergistic B─O/H-bond rigidification stabilizes triplet excitons and suppresses non-radiative decay, while the intrinsic chiral nematic structure preserves circular polarization. The resulting films exhibit tunable right-handed CPRTP emissions ranging from green to yellow to red under ambient conditions, ultralong phosphorescence lifetimes (419–805 ms), and high dissymmetry factor values (up to −0.29). Notably, these CPRTP films demonstrate exceptional photostability (stable for over six months) even after exposure to harsh hydrophilic conditions (soaking in acid, base, and salt solutions) and diverse organic solvents. Furthermore, the films possess mechanical flexibility, enabling their fabrication into various label products. Proof-of-concept demonstrations utilizing their fluorescence, ultralong phosphorescence, circular polarization, and time-dependent afterglow confirm their potential in multilevel anti-counterfeiting and optical information storage. This sustainable, scalable, shrimp-derived CPRTP platform provides new insights for designing high-performance biomass-based chiroptical phosphorescent materials.

A chiral narrow-band fluorophore undergoes aging-induced enhancement of fluorescence and circularly polarized luminescence (CPL) signals in the aggregate state, accompanied by a light-triggered aggregation-induced emission (AIE) to aggregation-caused quenching (ACQ) transition. The fusion strategy provides a straightforward and facile approach for constructing CPL materials with robust chiroptical performance.

Abstract

The development of circularly polarized luminescence (CPL) materials has garnered considerable interest owing to their promising applications in areas such as 3D displays and information encryption, with most efforts devoted to generating CPL activity and improving the dissymmetry factor (g _lum). However, the essential requirement of narrow-band emission for high-resolution organic optoelectronic applications is often overlooked. Here we employed the anthracene group as strong assembly unit and BODIPY as narrow-band fluorophore to construct with chiral binaphthyl moiety. The resulting compounds R/S-An-BDP displayed light-triggered transformation from aggregation-induced emission (AIE) to aggregation-caused quenching (ACQ) with CPL signals regulation. Moreover, R/S-An-BDP showed aging-driven narrow-band fluorescence with the full width at half maximum (FWHM) of 14 nm and CPL activity with the |g _lum| value of 0.048 in the aggregate state, attributed to the combined effect of BODIPY and anthracene unit. These findings highlight a functional group fusion strategy for constructing CPL materials with large g _lum values and narrow emission, offering a promising approach towards high-performance CPL materials.

Nature Communications, Published online: 03 November 2025; doi:10.1038/s41467-025-64663-w

The incorporation of a B–O Lewis pair into an MR-TADF molecule's skeleton results in a stable, saddle-shaped 3BON molecule, which exhibits highly efficient deep-blue TADF emission at 440 nm with a narrow FWHM of 18 nm and a small ΔE_ST of 0.12 eV. The resulting OLEDs achieve a record EQE_max of 26.3% in the deep-blue region.

Abstract

The quest for deep-blue emitters meeting the stringent BT.2020 color standard—requiring an ideal peak, narrow full-width-at-half-maximum (FWHM), and minimal singlet-triplet energy splitting (ΔEST)—is often hampered by the complex synthesis of multi-resonant thermally activated delayed fluorescence (MR-TADF) molecules. This work introduces a novel, selective strategy: incorporating B–O Lewis pairs into an MR-TADF system via intramolecular electrophilic borylation. By carefully controlling a tandem bora-Friedel–Crafts reaction, we synthesized the saddle-shaped molecule 3BON, despite the typical vulnerability of annulated boron structures to retro-bora-Friedel–Crafts reactions. 3BON exhibits highly efficient deep-blue TADF emission, with a peak at 440 nm, a narrow FWHM of 18 nm, and a low ΔEST of 0.12 eV. Compared to its parent emitter, DABNA-1, 3BON achieves a simultaneous blue-shift, narrowed FWHM, and reduced ΔEST. Principal Interacting Orbital (PIO) analysis indicates that unique orbital interactions involving the B–O Lewis pairs destabilize energy levels, causing the blue-shifted emission. Organic light-emitting diodes (OLEDs) utilizing 3BON demonstrated state-of-the-art performance. The device achieves a maximum external quantum efficiency (EQE_max) of 24.8% (at 9 wt.%) with ultra-deep blue narrowband emission (443 nm peak, 24 nm FWHM; CIE: 0.1554, 0.0454), fully satisfying the BT.2020 standard. Furthermore, 3BON's unique saddle-shaped architecture imparts remarkable doping tolerance, with EQE_max climbing up to 26.3% across a wide 0.520 wt.% doping range. A hyperfluorescent (HF) device also showed excellent performance (EQE_max = 23.8%, 441 nm peak, 19 nm FWHM). These results represent one of the best BT.2020-compliant OLED performances reported to date.

Nature Communications, Published online: 06 October 2025; doi:10.1038/s41467-025-63908-y

A series of inner-wall modified pagoda[5]arene (P5) derivatives were obtained in high yields under mild conditions via highly efficient and selective Diels–Alder (D–A) cycloadditions between P5 and the guests. These derivatives displayed the fixed conformation and stable chirality. Particularly, the neutral inner-wall modified P5 was resolved by HPLC and exhibited mirror-image circular dichroism and strong circularly polarized luminescence.

Abstract

Macrocyclic arenes with large cavities and chirality are attractive in supramolecular chemistry, but fixing their conformation and obtaining stable chirality remain significant challenges. The method of rim functionalization with bulky groups often involves multiple reactive sites, leading to poor selectivity and efficiency. Herein, the inner-wall modification as a promising yet underexplored strategy for achieving fixed conformation and stable chirality of pagoda[5]arene (P5) was developed. Consequently, a series of inner-wall modified P5 derivatives were obtained in high yields under mild conditions by the highly efficient and selective Diels–Alder (D–A) cycloadditions of P5 with (E)-1,2-bis(N-alkyl-4-pyridinium)ethylene guests, enabled by the guest pre-organization in the cavity microenvironment of P5. In contrast, reactions of 2,6-dimethoxyanthracene and the guests are not observed even at 170 °C due to the absence of the cavity microenvironment. Moreover, a neutral inner-wall modified derivative (P5py) was obtained by post-reaction demethylation. P5py exhibited stable planar chirality, and its enantiomers were efficiently resolved by chiral HPLC. Notably, the enantiomers showed mirror-imaged CD signals and strong CPL property. This work provides a new facile strategy for fixing the conformation and achieving the stable chirality of macrocyclic arenes with chiral large cavities, and thereby broadens their prospects for applications in supramolecular and materials chemistry.

Based on one-step phosphine-oxide post-modification strategy, the first B/N/P═O fused multiple resonance thermally activated delayed fluorescence (MR-TADF) emitters are developed. The resultant emitters exhibit excellent photophysical properties with high-efficiency, narrowband emission, enhanced reverse intersystem crossing rates and suppressed concentration quenching, and electroluminescence performances with high maximum external quantum efficiencies and minimal spectral broadening in a wide doping concentrations range of 1–20 wt%.

Abstract

Multiple-resonance thermally activated delayed fluorescence (MR-TADF) materials featuring high efficiency and narrowband emission are crucial for wide color-gamut organic light-emitting diodes (OLEDs), but they often suffer from complex synthesis and limited structural diversity. In this study, we report a one-step, metal-free phosphine-oxide (P═O) post-modification strategy to construct the first B/N/P═O fused MR-TADF emitters, PO-BCzBN and PO-tFBN. This strategy introduces a covalent P═O lock, enhancing the rigidity of the π-conjugation plane to maintain narrowband emission while simultaneously suppressing aggregation-caused quenching (ACQ) through the steric hindrance introduced by the trigonal pyramidal geometry of sp³-hybridized P atom. PO-BCzBN and PO-tFBN show photoluminescence emission peaks at 466 and 493 nm with narrow full widths at half maximum (FWHMs) of 21 and 23 nm in solution, near-unity photoluminescence quantum yields of 98% and 99%, rapid reverse intersystem crossing rates of 2.0 × 10⁴ and 2.1 × 10⁴ s⁻¹, and suppressed concentration quenching in films. Sensitizer-free OLEDs based on PO-BCzBN and PO-tFBN achieve maximum external quantum efficiencies of 21.6%–34.2% (electroluminescence emission peaks, λ _ELs, = 472–476 nm, FWHMs = 24–28 nm) and 28.3%–35.8% (λ _ELs = 496–500 nm, FWHMs = 26–27 nm) across a broad doping range (1–20 wt%), respectively, demonstrating superior resistance to spectral broadening and ACQ.