Highly efficient multiple resonance TADF emitters by hybridizing long-range and short-range charger transfer characteristics to enable narrowband and low roll-off OLEDs

Abstract

Multiple resonance thermally activated delayed fluorescence (MR-TADF) materials show great potential for ultrahigh-definition organic light-emitting diodes (OLEDs) owing to their exceptional luminescence efficiencies and narrow emission spectra. Nevertheless, the device performances of MR-TADF emitters typically suffer from significant efficiency loss under high current densities due to the slow reverse intersystem crossing (RISC) rates. Herein, we propose a straightforward yet effective strategy to introduce three typical spiral electron-acceptor fragments to an MR framework featuring hybridized short-range charge-transfer (SRCT) and long-range charge-transfer (LRCT) characteristics. Comprehensive photophysical and computational investigations of these MR-TADF materials demonstrated that the difference in the electron-withdrawing ability among the three acceptor units of the MR framework had a significant influence on the emission color, full-width at half-maximum (FWHM) and RISC rates. Remarkably, the sensitizer-free OLED based on BNAP demonstrated the best device performance, with an electroluminescent peak at 512 nm, an FWHM of 36 nm, CIE coordinates of (0.17, 0.68), and a maximum external quantum efficiency (EQE) of 36.1%. The EQE values at 100 cd m⁻² and 1000 cd m⁻² were 32.8% and 16.1%, respectively, revealing that the introduction of the LRCT feature effectively modulated the energy level and harnessed the high-energy triplet excitons to suppress efficiency roll-off.

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Introduction

Organic light-emitting diodes (OLEDs) with expansive viewing angles, exceptional contrast, ultra-thinness, and self-emissivity have been widely used in modern devices including smartphones, televisions, and computers.^1–3 In the last ten years, pure organic thermally activated delayed fluorescence (TADF) materials, as new-generation OLED emitters, have garnered widespread attention owing to their near 100% internal quantum efficiencies (IQEs) (achieved by utilizing the key reverse intersystem crossing (RISC) process from the lowest excited triplet (T₁) and singlet (S₁) states), high efficiencies comparable to those of commercial phosphorescent materials, and low production costs (due to avoiding the use of precious metals).^4–7 Conventional TADF materials are typically composed of strong donor–acceptor (D–A) moieties, enabling the complete separation of the HOMO and LUMO, thereby achieving small energy differences (ΔE_ST) between the singlet and triplet states.^8,9 However, the long-range charge-transfer (LRCT) transitions of these D–A architectures typically show a relatively broad full-width at half-maximum (FWHM > 70 nm) due to their large structural relaxation and vibrational coupling, making it hard for them to satisfy the rigorous demands of high-resolution displays.^10,11 In order to solve this problem, it is highly desirable to develop high efficiency and narrowband emission OLEDs without the aid of filter or optical microcavity effects, which could not only effectively decrease energy losses but also simplify the device fabrication process and save costs, thereby holding crucial practical significance for the development of OLEDs.

Recently, a fascinating design approach has emerged to address the color purity issues by utilizing the multiple resonance (MR) effect with atomic-scale separation between the HOMO and LUMO distributions through the use of electron-deficient boron atoms and electron-rich nitrogen atoms, resulting in a narrowband emission with an FWHM of <40 nm and excellent photoluminescence quantum yield (PLQY) close to 100%.^12–24 However, the restricted short-range charge-transfer (SRCT) nature of MR-TADF cores inevitably leads to an inefficient RISC process compared with those of their traditional D–A counterparts.^25–32 The corresponding devices exhibit serious efficiency roll-off at operational brightness levels due to triplet deactivation by the quenching effects of excitons, which largely limit their potential for commercialization. In order to facilitate the RISC process of MR-TADF emitters, many strategies, such as heavy atom integration,^{23,28,33–35} conjugation extension,^36–39 and substitution of electron-donating or -withdrawing groups, have been successfully proposed.^{20,21,29,40–43} However, these strategies often broaden the emission bandwidth (FWHM > 40 nm) due to the introduction of large deformation atoms and uncontrollable electron push–pull effect. The principles concerning molecular structure designs with a narrow FWHM and high RISC rate are still ambiguous and need further investigation.

Herein, we propose an effective and simple strategy for the hybridization of SRCT and LRCT characteristics of MR-TADF emitters by integrating three typical spiral electron-acceptor fragments (triphenyltriazine, acetophenone, and naphthalenedicarboximide) at the para-position of the B atom in the structure of the parent molecule BCz-BN, namely, BNTRZ, BNAP, and BNNDI (Fig. 1). When increasing the electron-withdrawing abilities of these auxiliary groups, the LUMO orbitals progressively shifted and localized toward the triphenyltriazine, acetophenone, and naphthalenedicarboximide groups, and the correlation between the LRCT and SRCT could effectively enhance the spin–orbit coupling (SOC) between the singlet and triplet excited states to facilitate the RISC process. Among them, BNAP exhibited the most effective hybrid SRCT and LRCT characteristics, culminating in a high PLQY (96%), an ultrafast singlet radiative decay (0.93 × 10⁸ s⁻¹), and a rapid RISC rate (k_RISC = 6.04 × 10⁴ s⁻¹). Moreover, a sensitizer-free device based on BNAP demonstrated the best EL performance with an EL peak at 512 nm, FWHM value of 36 nm, CIE coordinates of (0.17, 0.68), and maximum EQE of 36.1%. Meanwhile, the EQE values at 100 cd m⁻² and 1000 cd m⁻² were 32.8% and 16.1%, respectively. The smaller efficiency roll-off could be attributed to the facts that the introduction of LRCT characteristic adjusted the energy level and distribution of the excited states and increased the SOC, thereby promoting the rapid up-conversion of triplet excitons.

Fig. 1 Molecular design and chemical structures of BNTRZ, BNAP, and BNNDI.

Results and discussion

Molecular synthesis and characterization

The synthesis route of the three compounds is outlined in Scheme S1 (SI). Compound DtCzB-Bpin was obtained according to a previously reported procedure.²¹BNTRZ, BNAP, and BNNDI were obtained via Suzuki coupling reactions between DtCzB-Bpin and the respective acceptors. Their structures were fully characterized by ¹H and ¹³C NMR spectroscopies, mass spectrometry, and elemental analysis (Fig. S1–S9, SI). Their thermal stabilities were investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) (Fig. S10, SI). BNTRZ, BNAP, and BNNDI demonstrated excellent thermal stabilities with high decomposition temperatures (T_d) of 469 °C, 434 °C, and 501 °C, respectively. According to the DSC curves, a weak endothermic peak was observed at 206 °C for BNTRZ, corresponding to the glass transition temperature (T_g), while no obvious glass transitions were detected in the scanning curves of BNAP and BNNDI. The experimental data confirmed that these MR-TADF emitters met the processing requirements for the long-term evaporation processes of devices. Their electrochemical behavior was investigated by cyclic voltammetry to explore the influence of acceptor units with varying strengths (Fig. S11, SI). The HOMO energy levels of BNTRZ, BNAP, and BNNDI were evaluated to be −5.32, −5.34, and −5.41 eV, based on the onsets of their oxidation curves at 0.74, 0.76, and 0.83 V, respectively. Their onset reduction potentials, which were more strongly influenced by the acceptor groups, were measured to be −1.71, −1.65, and −1.46 V, respectively, exhibiting a clear increasing trend with the enhanced electron-withdrawing abilities of the acceptors. The LUMO energy levels were further determined to be −3.02, −3.08, and −3.27 eV, respectively. Apparently, the electrochemical bandgaps of the three compounds (2.30, 2.26, 2.14 eV for BNTRZ, BNAP, and BNNDI, respectively) could be effectively modulated by changing the electron-withdrawing abilities.

Single-crystal analysis

Single-crystal structure of BNTRZ was obtained through gradient sublimation (Fig. S12, SI). BNTRZ exhibited significant steric hindrance between the triphenyltriazine unit and BCz-BN core with a torsional angle of 59.30°, which was beneficial to suppress the strong π–π intermolecular interactions and reduce the non-radiative energy loss in its aggregated state. Weak C–H⋯π non-covalent interactions (2.785 Å) and C–H⋯N hydrogen bonding interactions (2.718 Å and 2.833 Å) were found, while intermolecular π⋯π interactions were absent in the packing structures of the BNTRZ crystal. This highly twisted molecular configuration and robust steric hindrance of BNTRZ can hinder the planar overlap of chromophores, weaken the intermolecular π⋯π stacking interactions, and suppress exciton collision and annihilation/quenching, enhancing its tolerance to doping concentration variations during device fabrication and effectively minimizing performance fluctuations caused by concentration changes.

Theoretical simulation

To understand the effect of different auxiliary acceptor units of the MR-TADF materials on their ground-state properties, theoretical investigations were performed using the density functional theory (DFT) method at the B3LYP/6-31G(d,p) level. The frontier orbital distributions and energy levels of these compounds are depicted in Fig. 2. The HOMOs of BNTRZ, BNAP, and BNNDI closely resembled those of BCz-BN, exhibiting a regular distribution in accordance with the MR effect. In contrast, the LUMO was progressively localized on the triphenyltriazine, acetophenone, and naphthalenedicarboximide fragments as the electron-withdrawing strength of the substituents increased, with LUMO energy levels of −1.82 eV, −1.95 eV, and −2.43 eV for BNTRZ, BNAP, and BNNDI, respectively. The trends in the orbital energies aligned well with the electrochemistry measurements (Fig. S11). Notably, the LUMO distribution of BNNDI became almost entirely localized on the acceptor unit due to the strong influence of the naphthalenedicarboximide moiety, while BCz-BN acted as a donor group, exhibiting a typical LRCT characteristic of conventional D–A-type TADF emitters. Both BNTRZ and BNAP demonstrated oscillator strengths (f) exceeding 0.2 owing to the hybrid SRCT and LRCT orbital distribution of this molecular design, indicating their rapid radiative decay processes and high PLQYs. In contrast, the LRCT-dominated transition in BNNDI yielded a significantly lower f value of 0.0446, typically leading to a low PLQY.

Fig. 2 HOMO–LUMO energies, distributions, energy band gaps, oscillator strengths, state levels and SOC constants of BNTRZ, BNAP, and BNNDI.

In addition, natural transition orbital (NTO) analysis was performed to reveal the changes induced by the secondary acceptors using time-dependent DFT (TD-DFT). As shown in Fig. S13 (SI), the S₁ states of BNTRZ and BNAP exhibited an obvious hybrid orbital distribution that combined both SRCT and LRCT characteristics, in which the “particles” showed slight extensions toward the π-bonding acceptors. Meanwhile, both BNTRZ and BNAP exhibited extremely small reorganization energies of 0.2078 and 0.2160 eV, respectively, illustrating that the additional LRCT in the S₁ states would not destroy the multiple resonance effect due to the relatively weak acceptors (Fig. S14, SI). In contrast, the S₁ states of BNNDI were completely separated, in which the ‘‘holes’’ and ‘‘particles’’ were located on the BCz-BN core and acceptor, respectively, demonstrating the dominant LRCT feature. Meanwhile, the higher-lying excited states (T₂ and T₃) of BNTRZ and BNAP exhibited LRCT or hybridized local charge-transfer (HLCT) features,^44–46 and the calculated energy levels of the triplets (T₂ and T₃) and singlet (S₁) were also close. Owing to the involvement of LRCT excited states that are distinct from the original SRCT feature of the MR core, both BNTRZ and BNAP displayed significantly larger SOC matrix elements of 0.10 and 0.12 cm⁻¹ and 0.37 and 0.10 cm⁻¹ for 〈S₁|Ĥ_SOC|T₂〉 and 〈S₁|Ĥ_SOC|T₃〉, respectively. These results implied that introducing weak acceptors did not change the SRCT properties but facilitated the spin-flip of triplet excitons and provided more channels to accelerate the RISC rate from the high-lying triplet states to singlet state.

Photophysical properties

The key photophysical properties were analyzed in dilute toluene (1 × 10⁻⁵ M) using UV-vis absorption and photoluminescence (PL) spectroscopies at room temperature. As shown in Fig. 3 and Table 1, BNTRZ, BNAP, and BNNDI exhibited n–π* and π–π* transition absorption bands below 400 nm from their molecular backbones, along with the SRCT transition of the MR segment at peaks of 473, 475, and 473 nm, respectively. From the absorption onset, the optical bandgaps of BNTRZ, BNAP, and BNNDI were calculated to be 2.46, 2.42, and 2.36 eV, respectively. Compared with BCz-BN, BNTRZ and BNAP exhibited slight redshifts, with emission peaks at 493 and 497 nm and high absolute PLQYs of 82% and 93%, respectively, owing to hybridization of the SRCT and LRCT characteristics within the entire molecule. It is worth noting that the FWHM values of BNTRZ (24 nm) and BNAP (24 nm) were comparable to that of BCz-BN (23 nm), implying that the weak acceptor subunits did not induce additional detrimental structural relaxation. In sharp contrast, the PL spectrum of BNNDI displayed a relatively broad emission band at 519 nm with a significantly increased FWHM value of 45 nm and Stokes shift of 46 nm, respectively, indicating that the strong electron-withdrawing naphthalenedicarboximide group could induce the formation of the low-lying LRCT state. From the onsets of the fluorescence and phosphorescence spectra, the S₁/T₁ energy levels of BNTRZ, BNAP, and BNNDI were estimated to be 2.69/2.55 eV, 2.64/2.53 eV, and 2.55/2.33 eV, with corresponding ΔE_ST values of 0.14, 0.11, and 0.22 eV, respectively. The larger ΔE_ST of BNNDI largely impeded the T₁ → S₁ spin-flipping, leading to a reduced RISC rate and exciton utilization. We further investigated the solvatochromic absorption and PL spectra of BNTRZ, BNAP, and BNNDI in solvents with different polarities, from hexane to dichloromethane (Fig. S15, SI). Both BNTRZ and BNAP showed minimal solvent-dependent spectral shifts in their absorption and emission profiles with high PLQYs (75–93%) from low-polarity hexane to high-polarity dichloromethane, implying the dominant SRCT characteristic in their ground and S₁ states. In contrast, BNNDI demonstrated dramatic solvatochromism (redshift of 81 nm and FWHM of 116 nm) and relatively lower PLQYs (45–79%), indicating its strong LRCT characteristic and intermolecular CT nature, which agreed well with the theoretical results (Table S1, SI).

Fig. 3 (a) UV/vis absorption, PL (298 K), and phosphorescence (77 K) spectra of BNTRZ, BNAP, and BNNDI in toluene (1 × 10⁻⁵ M). (b) Emission spectra of the doped films using PhCzBCz as the host matrix.

Table 1 Summary of the photophysical properties of BNTRZ, BNAP, and BNNDI

Compound	λ abs (nm)	λ max,PL (nm)	FWHM^b (nm)	Stokes shift^a (nm)	S1^a (eV)	T1^a (eV)	ΔEST^a (eV)	E g (eV)	PLQY^b (%)	k RISC (10^4 s^−1)
a In 10^−5 M toluene solution. b In 10^−5 M toluene solution and doped films of emitters in PhCzBCz. c The rate constants of RISC in doped films of emitters in PhCzBCz.
BNTRZ	473	493/498	24/34	20	2.69	2.55	0.14	2.46	82/85	1.39
BNAP	475	497/508	24/32	22	2.64	2.53	0.11	2.42	93/96	6.04
BNNDI	473	519/540	45/57	46	2.55	2.33	0.22	2.36	73/79	0.81

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To gain a deeper understanding of the solid-state properties of the three emitters, we prepared thin films using 9-(2-(9-phenyl-9Hcarbazol-3-yl)phenyl)9H-3,9′-bicarbazole (PhCzBCz) as the host matrix with optimized doping concentrations for each device.²¹ As shown in Fig. 3b, BNTRZ, BNAP, and BNNDI exhibited blue-green and yellow emissions at 498, 508, and 540 nm, with corresponding FWHM values of 34, 32, and 57 nm, respectively. Notably, the absolute PLQYs of the doped films were measured to be 85%, 96%, and 79%, respectively. Compared with their solution states, BNTRZ and BNAP showed minor emission redshifts and FWHM broadening, while BNNDI displayed more significant changes. This phenomenon likely originated from the molecular aggregation between the guest molecules and guest–host interactions in the solid state. The transient PL decay spectra of BNTRZ, BNAP, and BNNDI demonstrated typical dual-component lifetime characteristics of a TADF nature with rapid transient lifetimes (τ_p) of 4.3, 5.5, and 6.3 ns, and delayed lifetimes (τ_d) of 100.32, 31.27, and 184.05 μs, respectively (Fig. S16, SI). The temperature-dependent transient PL spectra of BNTRZ, BNAP, and BNNDI in the doped thin films also confirmed their TADF characteristics. Based on the lifetimes and PLQYs, we calculated their detailed photophysical parameters using previously described formulas (Table S2, SI). All the three compounds showed high radiative decay rates (k_r) around 10⁸ s⁻¹. However, BNTRZ and BNNDI exhibited substantial non-radiative decay rates (k_nr) of 25.08 × 10⁶ and 22.40 × 10⁶ s⁻¹, respectively, indicating significant energy loss. In contrast, BNAP demonstrated a relatively smaller k_nr of 3.88 × 10⁶ s⁻¹, which was two orders of magnitude lower than the k_r value (0.93 × 10⁸ s⁻¹), suggesting predominant radiative energy release. Notably, BNAP achieved the highest k_RISC of 6.04 × 10⁴ s⁻¹ among the three MR-TADF molecules, likely attributable to its unique SRCT/LRCT hybrid character that effectively promoted the RISC processes. Conversely, BNNDI showed the lowest k_RISC (0.81 × 10⁴ s⁻¹) due to its excessively large ΔE_ST.

Electroluminescent properties

To investigate the electroluminescent (EL) properties of BNTRZ, BNAP, and BNNDI, optimized multilayer devices were fabricated with the following configurations: ITO/HATCN (5 nm)/TAPC (30 nm)/TCTA (10 nm)/mCP (5 nm)/x wt% emitters in PhCzBCz (30 nm)/TmPyPb (40 nm)/LiF (1 nm)/Al (120 nm). Here, ITO, HATCN, TAPC, TCTA, TmPyPb, LiF, and Al acted as the anode, hole-injection, hole-transporting, electron-blocking, electron-transporting, and electron-injection layers, and cathode, respectively. In the light-emitting layers, the optimal doping concentrations of BNTRZ, BNAP, and BNNDI as guest materials in PhCzBCz were explored. The corresponding energy level diagram and the chemical structures of the materials used are presented in Fig. 4. To achieve effective energy transfer from the host to the emitters and further optimize device performance, different doping concentrations (1, 2, 3, and 5 wt% for BNAP and BNNDI and 5, 10, 15, and 20 wt% for BNTRZ) were implemented. In contrast to the BNAP- and BNNDI-based devices, no obvious bathochromic shifting or spectral broadening were observed in the OLEDs using BNTRZ as the emitter at doping concentrations of up to 20 wt%, which was derived from the alleviated intermolecular interactions owing to the highly twisted molecular configuration, effectively facilitating it to hold decent brightness and efficiency at high doping concentrations. The numerical data illustrating the EL performance of these devices are provided in Fig. 5, Table 2, and Fig. S17–S19, Table S3, respectively.

Fig. 4 Energy level diagram (a) and chemical structures (b) of the materials used in the devices.

Fig. 5 (a) EL spectra at 5 V; (b) luminescence and current density versus voltage; (c) EQE versus luminance curves; and (d) CE/PE versus luminance curve characteristics of the BNTRZ-, BNAP-, and BNNDI-based devices.

Table 2 Summary of the EL data of the BNTRZ-, BNAP- and BNNDI-based devices

Emitters	λ EL (nm)	FWHM (nm)	V on (V)	L max (cd m^−2)	CE^a (cd A^−1)	PE^b (lm W^−1)	EQE^c (%)	Roll-off^d (%)	CIE (x, y)
a CEs of maximum/at 100 cd m^−2/1000 cd m^−2. b PEs of maximum/at 100 cd m^−2/1000 cd m^−2. c EQEs of maximum/at 100 cd m^−2/1000 cd m^−2. d EQE roll-offs at 100 cd m^−2.
BNTRZ	496	34	3.3	21 371	47.2/28.2/16.6	42.9/21.9/10.4	20.6/13.5/7.7	34.5	(0.12, 0.50)
BNAP	512	36	3.5	54 089	115.9/97.7/49.0	95.8/72.4/29.9	36.1/32.8/16.1	9.1	(0.17, 0.68)
BNNDI	548	72	3.1	39 050	93.5/58.7/17.3	89.0/49.6/10.7	25.6/15.1/4.9	41.0	(0.40, 0.57)

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All the doped OLEDs exhibited turn-on voltages below 3.5 V, suggesting efficient carrier injection and transportation within the devices. In addition, the EL spectra of the best devices maintained spectral stability under varying voltages (4–10 V) and showed single-peak emission without parasitic bands, indicating their excellent spectral stability and efficient energy transfer (Fig. S20, SI). The doped device based on BNTRZ exhibited a blue-green emission with an EL peak at 496 nm and an FWHM of 34 nm. At a doping concentration of 10 wt%, the device achieved the maximum EQE, luminance (L_max), power efficiency (PE_max), and current efficiency (CE_max) of 20.6%, 21 371 cd m⁻², 42.9 lm W⁻¹, and 47.2 cd A⁻¹, respectively. Even at 20 wt% doping concentration, the maximum EQE remained at 15.3% and the emission spectrum was almost unchanged (Fig. S17). However, significant efficiency roll-off was observed in BNTRZ-based device due to the weak hybridization of the SRCT and LRCT characteristics and low RISC rate, with the EQE decreasing from 13.5% at 100 cd m⁻² to 7.7% at 1000 cd m⁻². For the BNAP-based OLED, the optimal EL performance was achieved at a 3 wt% doping concentration. Owing to the hybridization of the SRCT and LRCT characteristics, the device showed a green emission at 512 nm with an FWHM of 36 nm and CIE coordinates of (0.17, 0.68), approaching the NTSC green standard (0.21, 0.71), with remarkable L_max, CE_max and PE_max values of 54 089 cd m⁻², 115.9 cd A⁻¹, and 95.8 lm W⁻¹, respectively. Benefiting from the highest PLQY and k_RISC among the three MR-TADF emitters, the device achieved an EQE as high as 36.1% and maintained 32.8% even at a luminance of 100 cd m⁻² with a relatively mild efficiency roll-off of 9.1%. The relatively narrowband emission, low efficiency roll-off and enhanced device performance of the BNAP-based OLED were comparable to those of the most-efficient mono-boron MR-TADF-based devices with similar electroluminescent spectra (Table S4, SI). In contrast, the BNNDI-based device at 2 wt% doping displayed a broad, featureless yellow-green emission at 548 nm (FWHM = 72 nm) and a maximum EQE of 25.6%, completely deviating from the typical narrowband characteristics of MR-TADF materials and resembling conventional D–A-type TADF emitters. The performance differences among the BNTRZ-, BNAP-, and BNNDI-based devices originated from their distinct emission mechanisms. The LRCT-dominated emission in BNNDI led to a stronger vibronic coupling and structural relaxation, causing color purity and efficiency degradation.

Conclusions

By addressing the critical challenge of simultaneously achieving a narrow FWHM and rapid RISC process in OLEDs, this work introduced three MR-TADF emitters, BNTRZ, BNAP, and BNNDI, integrating three typical spiral electron-acceptors into the para-position of the B atom in the core of the parent molecule BCz-BN, with an aim to investigate the interplay between the SRCT and LRCT characteristics. Importantly, the hybridization of the SRCT and LRCT characteristics enhanced the radiative decay for high PLQYs and improved the SOC between the excited singlet and triplet states to promote the RISC processes while maintaining narrowband emissions. Benefiting from the excellent hybridization of the SRCT and LRCT characteristic of BNAP, the sensitizer-free OLED demonstrated the best device performance, with an EL peak at 512 nm, FWHM of 36 nm, CIE coordinates of (0.17, 0.68), and a maximum EQE of 36.1%. The EQE values at 100 cd m⁻² and 1000 cd m⁻² were 32.8% and 16.1%, respectively, which were attributed to the faster k_RISC of BNAP. Overall, these findings suggest that the introduction of an LRCT characteristic into an SRCT-dominated skeleton represents a promising strategy for enhancing the PLQY and accelerating the RISC processes, thus facilitating exceptional performance with high efficiency and low roll-off. This work provides an effective approach to suppress the efficiency roll-off of multiple resonance emitters.

Author contributions

The design, synthesis, characterization of compounds and device fabrication were completed by Yangze Xu, Liang Wan and Lveting Zhang. Zhuang Cheng and Xiaobo Ma provided assistance in the synthesis. Yin Hu provided support for theoretical calculations. Futong Liu provided assistance and guidance in photophysical and device characterizations. Yan Wang and Ping Lu guided the entire work and polished the manuscript.

Conflicts of interest

There are no conflicts to declare.

Data availability

The authors confirm that the data supporting the findings of this study are available within the article and its SI. See DOI: https://doi.org/10.1039/d5tc02393a

Acknowledgements

This research was supported by the Changchun Science and Technology Bureau (23JQ05) and the Open Fund of the State Key Laboratory of Luminescent Materials and Devices (South China University of Technology, 2025-skllmd-09).

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Footnote

† Dr Yangze Xu, Dr Liang Wan, and Dr Lveting Zhang contributed equally to this work.

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