14 Aug 11:39
Chem. Sci., 2025, 16,16770-16779
DOI: 10.1039/D5SC02235E, Edge Article
Open Access
Xinyue Yan, Shi-Yu Song, Shicong Liang, Kai-Kai Liu, Xiao-Ting Liu, Chao Lu
Based on the synergy of coordination and D–A interactions, D guests have been introduced into MOFs composed of A ligands to manipulate TSCT interactions. As a result, TADF-type host–guest MOFs for X-ray scintillators have been achieved.
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11 Aug 12:34
by Xuming Hu,
Zhiyu Deng,
Zhiheng Wang,
Qishen Chen,
Jie Liang,
Xiaoxian Song,
Hai Bi,
Yue Wang
By introducing the frontier molecular orbital perturbation strategy into hole-blocking molecular skeletons, the electron energy level can precisely align with the n-doping electron transport layer, enabling low-voltage and voltage-stable sensitized fluorescence. Consequently, OLEDs based on proof-of-concept demonstrate exceptionally high power efficiencies of 312.5 lm W−1 in maximum and 211.7 lm W−1 at 10 000 cd m−2 with stabilized voltage drifts of 0.158 V (500 h aging times).
Abstract
Advancements of organic light-emitting diodes (OLEDs) based on sensitized fluorescence have demonstrated promising efficiency and superior color purity. Nevertheless, overcoming the driving voltage issues, including low operating voltage and clarification of voltage increase during electrical aging, remains challenging. Here, it is disclosed that electron energy level mismatch at the hole-blocking layer (HBL)/n-doping electron transport layer (n-ETL) interface dominates the voltage stability of device degradation. To address this interfacial bandgap, a frontier molecular orbital perturbation strategy is developed through integrating auxiliary electron-withdrawing groups into the HBL skeleton, enabling low-voltage and voltage-stable phosphorescent- sensitized fluorescence (PSF) within a new conception of the p-i-n type OLED framework. Optimized pure-green PSF OLEDs based on proof-of-concept achieve record-high power efficiencies of 312.5 and 211.7 lm W−1 at maximum and 10 000 cd m−2, with stabilized voltage drifts of 0.158 V after 500 h aging times and excellent T95 (lifetime to 95% of the initial luminance) of 43 300 h. Degradation analyses reveal that continuous voltage drifts stem from the electron transport deterioration by metal-migration of n-ETL, differing from the brightness decline mechanism (attributed to electron trapping centers). The findings provide critical insights into driving voltage bottlenecks, offering guidance for achieving high-performance sensitized fluorescence OLEDs.
11 Aug 12:30
by Dong Wang,
Wanting Ju,
Mengyu Ren,
Ziyu Su,
Zhiping Yan,
Junqiao Ding,
Ning Su
Two MR-TADF molecules BCz-BNDCzMe and BCz-BNDCzPh are reported with large steric hindrance groups 4,4′-bicarbazole derivatives incorporated into the MR core (BCz-BN). Remarkably, their devices achieve the maximum external quantum efficiency of 26.75% and 28.31%, respectively.
Abstract
Organic light-emitting diodes (OLEDs) employing multiple resonance-thermally activated delayed fluorescence (MR-TADF) emitters exhibit high exciton utilization efficiency and outstanding color purity. Nevertheless, typical MR-TADF emitters possessing well-developed conjugated planarity often encounter significant aggregation-induced quenching (ACQ) effect through π–π stacking, which substantially impacts device efficiency and color purity. To address these issues, in this work, large steric hindrance groups 4,4′-bicarbazole derivatives are incorporated into the MR core (BCz-BN) to obtain two target molecules, namely BCz-BNDCzMe and BCz-BNDCzPh. Compared to BCz-BN, which exhibits an electroluminescence (EL) emission peak at 488 nm with a full width at half maximum (FWHM) of 30 nm, BCz-BNDCzMe and BCz-BNDCzPh demonstrate blue-shifted emissions peaking at 481–482 nm and featuring narrower FWHM values of 25–26 nm. Remarkably, the maximum external quantum efficiency (EQEmax) of 26.75–28.31% is achieved for BCz-BNDCzMe and BCz-BNDCzPh based devices at high doping concentrations (10–20 wt.%). These values are significantly higher than the EQEmax of 20.50% for BCz-BN-based devices at a 3 wt.% doping level. These findings unequivocally indicate that incorporating a bulky steric hindrance group into the MR-TADF core efficiently mitigates interchromophore interactions, thereby further suppressing the ACQ effect and enhancing device efficiency at high doping concentrations.
11 Aug 12:04
by Jiaju Shi,
Yusheng Zhou,
Faxu Lin,
Ge Li,
Wenqing Yan,
Guodong Liang,
Ben Zhong Tang,
Wei Qin
Near-infrared afterglow (NIR-AG) materials are successfully developed using a facile relay phosphor strategy and an efficient phosphorescence resonance energy transfer process. Bright NIR-AG materials are first reported with aggregation-induced emission (AIE) characteristics and an ultralong lifetime of 269 ms at an emission maximum of 822 nm, demonstrating the best performance among the organic afterglow materials and highlighting their versatile applications.
Abstract
Organic materials with afterglow properties have gained significant interest owing to their long lifetimes and potential applications. However, most of these organic materials emit light in the visible region, posing a significant challenge for developing near-infrared afterglow (NIR-AG). In this study, NIR-AG materials with ultralong lifetimes and aggregation-induced emission (AIE) features are fabricated using a relay phosphor strategy. Red relay phosphors are easily fabricated by incorporating pyrene derivatives into an electron-rich matrix. The triplet excited energy of the relay phosphor is manipulated and effectively transferred to the excited singlet state of the AIE molecule via phosphorescence resonance energy transfer. Following the radiative decay of the excitons, an exceptional NIR-AG is ultimately generated with an ultralong lifetime of 269 ms at an emission maximum of 822 nm. The NIR-AG materials with ultralong lifetimes and AIE characteristics are reported for the first time, demonstrating one of the best performances among the organic afterglow materials. Notably, the NIR-AG materials can be processed into diverse aggregated forms for advanced anticounterfeiting, fingerprint identification, information encryption, and tissue penetration imaging using red and NIR dual-delay channels with good performances. These promising findings are encouraging for the development of organic NIR-AG materials with exceptional performance.
11 Aug 12:03
by Qihuan Li,
Yizhou Song,
Jiaqi He,
Junsheng Zhang,
Guo Zou,
Yixiang Cheng
This study reports two compounds crystallizing in achiral point groups (2/m and 1¯$\bar{1}$) that exhibit circularly polarized room-temperature phosphorescence. Mechanistic investigations reveal that the synergistic effect of intermolecular π–π stacking and C─H···N hydrogen bonding during crystallization induces symmetry breaking, facilitating directed helical assembly. The photoluminescence dissymmetry factors (g
lum) reach 5.5 × 10−2 (543 nm) and 4.3 × 10−2 (550 nm), respectively.
Abstract
Very recently, considerable attention has been given to pure organic circularly polarized room-temperature phosphorescent (CP-RTP) materials due to their unique photophysical properties. However, the directed construction of optically active phosphorescent signals within achiral systems remains a formidable challenge. In this study, two achiral crystals, 2CN4S and 2F4S, belonging to the achiral point groups 2/m and 1¯$\bar{1}$, exhibit strong CP-RTP emission with high photoluminescence dissymmetry factors (g
lum) up to 5.5 × 10−2 (543 nm) and 4.3 × 10−2 (550 nm), respectively. This phenomenon is attributed to the intrinsic mirror-antiparallel molecular conformations induced by the targeted substitution of cyano/fluoro groups, which spontaneously assemble into symmetry-breaking helical superstructures through synergistic C─H···N hydrogen bonding and π–π interactions. This work not only establishes a novel approach for CP-RTP material design but also overcomes structural constraints in optically active materials within achiral point group systems.
11 Aug 12:03
by Yu Mei Hu,
Maggie Ng,
Xiongkai Tang,
Cangyu Wang,
Yuqi Huang,
Xianglian Zhu,
Panpan Li,
Season Si Chen,
Man‐Chung Tang
This work presents a strategic molecular design utilizing fused B/N and C ═ O/N units within the MR-TADF framework to enhance molecular rigidity and accelerate RISC, resulting in efficient sky-blue OLEDs. BNTO-based hyper-fluorescence OLEDs achieved a moderate EQE of 19.4% and a LT70 of 500 h at 1000 cd m−2, emphasizing the importance of structural rigidification and excited-state engineering for color purity and stability.
Abstract
Blue-emitting multiple-resonance thermally activated delayed fluorescence (MR-TADF) emitters with high photoluminescence quantum yield (PLQY), high robustness with short-lived emission lifetime is particularly desired for the development of organic light-emitting diodes (OLEDs). In this study, a series of MR-TADF molecules featuring fused boron/nitrogen (B/N) and C ═ O/N frameworks is reported. These emitters namely BNO, BNDO, and BNTO are systematically designed and synthesized to investigate the impact of molecular rigidity or planarity toward their excited-state dynamics through stepwise intramolecular electrophilic acylation reactions. Computational studies and single-crystal X-ray diffraction data revealed the enhanced planarity of BNDO and BNTO. Upon photoexcitation, these compounds exhibited blue emission with PLQYs of approaching unity and short-lived delayed lifetimes (<2 µs). BNTO-based OLEDs achieved sky-blue emission peaking at 489 nm, a moderate device operational lifetime of over 500 h at 70% of the initial brightness (LT70) at 1000 cd m−2, which shows longer device stability when compared with BNO and greener emission when compared to BNDO. This study highlights that manipulation of the rigidity of compounds and emissive states of MR-TADF compounds is essential in achieving blue emission and improving OLED operational stability.
11 Aug 12:03
by Yaoyu Xie,
Shengxiong Wu,
Zihao Zhu,
Jingmin Wang,
Zhiyuan Kuang,
Lintao Zhang,
Alim Abdurahman,
Qiming Peng,
Xin Ai
Two luminescent radicals have been synthesized that feature through-space charge-transfer (TSCT) excited states. The spatial separation and non-bonding character between the donor and radical units suppress electron-vibrational coupling, resulting in CZP-FR-TTM showing a photoluminescence quantum efficiency (PLQE) of 64.3% and an ultralow non-radiative decay rate of 1.3 × 10⁶ s−1. Weak orbital coupling leads to non-Aufbau electronic structures, thereby enhancing the radical stability.
Abstract
High-performance luminescent radicals featuring donor-radical (D-R) charge-transfer (CT) excited states have emerged as promising candidates for optoelectronic applications. However, prior studies have predominantly focused on through-bond charge-transfer (TBCT) mechanisms. In this work, we report the first examples of luminescent radicals based on TTM (tris(2,4,6-trichlorophenyl)methyl radical) with through-space charge-transfer (TSCT) excited states, represented by TPA-FR-TTM and CZP-FR-TTM. Spatial separation and non-bonding character between the donor and radical units minimizes electron-vibrational coupling and effectively suppresses non-radiative decay. As a result, CZP-FR-TTM exhibits an outstanding photoluminescence quantum efficiency (PLQE) of 64.3% and an ultralow non-radiative decay rate of 1.3 × 106 s−1, among the lowest ever reported for luminescent radicals. Furthermore, the reduced electronic coupling leads to non-Aufbau electronic structures, enhancing radical stability. These findings establish TSCT as a powerful design strategy for high-performance and stable luminescent radicals, opening new avenues for open-shell optoelectronic materials.
07 Aug 16:03
by Javier Urieta‐Mora,
Seung Ju Choi,
Jaeki Jeong,
Silvia Orecchio,
Inés García‐Benito,
Manuel Pérez‐Escribano,
Joaquín Calbo,
Likai Zheng,
Minseop Byun,
Seyeong Song,
Gi‐Hwan Kim,
Shaik M. Zakeeruddin,
Seog‐Young Yoon,
Yimhyun Jo,
Agustín Molina‐Ontoria,
Enrique Ortí,
Nazario Martín,
Michael Grätzel
Fluorene-functionalized spiro-phenothiazine (PTZ-Fl) exhibits strong Li+ affinity and thermal stability, enabling a PCE of 25.75% in small-area cells and 22.07% in 25 cm2 modules. Under ISOS-L3 conditions, PTZ-Flbased devices retain over 80% efficiency after 1000 hours, demonstrating superior stability and scalability compared to spiro-OMeTAD for next-generation perovskite solar cells.
Abstract
Improving both the efficiency and long-term stability of perovskite solar cells (PSCs) is critical for their commercial deployment. Despite the widespread use of spiro-OMeTAD as a hole-transporting material (HTM), its inhomogeneous doping behavior and susceptibility to moisture and heat have hindered its large-scale industrial implementation. Here, a family of spiro-phenothiazine-based HTMs (PTZ) is reported to address these drawbacks. Among them, the fluorene derivative (PTZ-Fl) shows a larger Li+ affinity and forms a compact interphase by intercalation in the perovskite passivating layer that prevents Li+ migration. PSCs incorporating PTZ-Fl exhibit power conversion efficiencies (PCEs) up to 25.8% (certified 25.2% under reverse scan), retaining 80% of their initial performance after 1000 h under ISOS-L-3 protocol. Furthermore, a 5 × 5 cm mini-module reaches a PCE of 22.1%, surpassing spiro-OMeTAD-based PSCs and retaining over 85% of its efficiency after 1100 h under ISOS-D-1 protocol. These results demonstrate that PTZ-Fl not only enables high PCEs but also substantially improves operational stability, offering a promising pathway toward the large-scale deployment of next-generation PSCs.
07 Aug 16:00
by Youhei Chitose,
Gomathi Vinayakam Mageswari,
Ryota Zenke,
Toshiharu Ide,
Shintaro Kohata,
Ja‐Hon Lin,
Tzu‐Chau Lin,
Youichi Tsuchiya,
Chihaya Adachi
A rational molecular design strategy is presented for simultaneously enhancing two-photon absorption (2PA) and thermally activated delayed fluorescence (TADF) by incorporating electron-withdrawing units into a CzTRZ scaffold. The resulting materials exhibit high 2PA cross-sections, efficient reversed intersystem crossing, and excellent OLED performance, opening new possibilities for advanced imaging probes and organic semiconductors.
Abstract
The simultaneous realization of two-photon absorption (2PA) and thermally activated delayed fluorescence (TADF) in a single molecular system remains challenging due to an inherent trade-off in their molecular design requirements. In this study, we present a strategy to enhance both properties by introducing electron-withdrawing substituents into the CzTRZ scaffold, thereby leveraging an electron-withdrawing-enhanced intramolecular charge transfer (EWICT) character. The incorporation of TRZCF3 and TRZCN units effectively enhances the charge transfer (CT) character of CzTRZ, resulting in high 2PA cross-sections (156 GM for CzTRZCF3
and 200 GM for CzTRZCN) and a reduced singlet-triplet energy gap (ΔE
ST = E
S1 – E
T1). Computational and experimental studies reveal that incorporating TRZCF3 and TRZCN units selectively stabilizes the S1 state and reduces ΔE
ST, significantly facilitating the reversed intersystem crossing (RISC) process. Notably, 1c exhibits the fastest RISC rate (k
RISC), leading to superior TADF properties and an external quantum efficiency (EQE) of 13.5% in OLEDs. Moreover, a relatively high two-photon brightness of 174 GM is estimated for 1c. These findings demonstrate a rational molecular design strategy for the synergistic enhancement of 2PA cross-sections and excellent OLED performance, paving the way for applications in advanced imaging probes and organic semiconductors.
07 Aug 15:53
by Yan‐Xin Zheng,
Li‐Gao Liu,
Yu‐Yao Zhou,
Shu‐Ya Yang,
Xin‐Qi Zhu,
Xin Hong,
Bo Zhou,
Long‐Wu Ye
![Copper-Catalyzed Asymmetric [2 + 2 + 2] Cycloaddition of Diynes via Vinyl Cations](https://onlinelibrary.wiley.com/cms/asset/e6ab5379-a911-49e0-9bb9-496c62153bb2/anie202514641-gra-0001-m.png)
A copper-catalyzed asymmetric [2 + 2 + 2] cycloaddition of diynes via vinyl cations has been disclosed, enabling the efficient and practical synthesis of valuable chiral polycyclic indoles with excellent yields and unprecedented diastereo- and enantioselectivities. This reaction features the first asymmetric [2 + 2 + 2] cycloaddition via vinyl cations and the first enantioselective triyne cyclization for the construction of carbon stereocenters.
Abstract
Catalytic asymmetric [2 + 2 + 2] cycloaddition of diynes represents an efficient and atom-economical strategy for the assembly of valuable chiral cyclic targets in a single step. However, this strategy traditionally relies on the cyclometallation process. Moreover, there are no versatile asymmetric [2 + 2 + 2] cycloaddition methods for diynes that are compatible with C─C double/triple bonds and C─X double bonds. Here, we disclose a copper-catalyzed asymmetric [2 + 2 + 2] cycloaddition of diynes via vinyl cations. This universal [2 + 2 + 2] cycloaddition is suitable for the asymmetric cycloaddition of diynes with various C─C double/triple bonds and C─X double bonds, leading to a range of valuable chiral hexahydropyrrolocarbazoles, tetrahydropyrrolocarbazoles, and tetrahydropyran[4,3-b]indoles in generally excellent yields with excellent diastereo- and enantioselectivities. Importantly, this protocol features the first asymmetric [2 + 2 + 2] cycloaddition via vinyl cations, and constitutes the first construction of carbon stereocenters in triyne cyclization.
03 Aug 19:20
by Yulong Shi,
Wei Yang,
He Zhang,
Cheng Zhong,
Shaolong Gong,
Changying Yang
A near-infrared polycyclic boron/nitrogen-embedded type I photosensitizer (PS) featuring multiple-resonance (MR) is designed and facilely synthesized, which is capable of efficiently generating high toxic superoxide anion radicals (O2
•−) and exhibits a remarkable photothermal conversion efficiency exceeding 50% under laser irradiation. The MR-configured PS achieves a superior anti-tumor efficacy both in vitro and in vivo synergistic phototherapy.
Abstract
Type I photosensitization is of particular significance in the anaerobic tumor treatment. Nonetheless, the development of high-performance type I photosensitizers (PSs) remains challenging, due to weak absorption and inefficient intersystem crossing (ISC) progress. Herein, an effective approach toward a near-infrared (NIR) type I PS (NIR-BN) is demonstrated using a boron/nitrogen-embedded polycyclic aromatic hydrocarbon with multiple-resonance (MR) character, for the first time. A small singlet-triplet splitting (ΔE
ST = 0.09 eV) and high molar extinction coefficient (3.3 × 104 M−1 cm−1) of the NIR MR-configured PS supports an efficient ISC for the triplet sensitization. The distorted molecular configurations induce multi-model structural relaxations after the optical excitation, resulting in a remarkable photothermal conversion efficiency exceeding 50% for NIR-BN nanoparticles. Of note, the nanoparticles are capable of generating the highly toxic superoxide anion radical (O2
•−) under 660 nm laser irradiation, benefiting from the vigorous intramolecular dihedral angle vibrations in the excited states. Consequently, the biocompatible PS demonstrates superior performance for in vivo synergistic photodynamic and photothermal therapies.
03 Aug 18:32
by Jianwei Liang,
Lingyun Zhu,
Yuanping Li,
Gang Xu,
Haixiang Han,
Yuanming Li,
Zheng Zhou
The removal of {FeCp} moieties in two ferrocene-dopped cycloarylenes via reductive cleavage approach unveils the intrinsic optical properties of anionic cycloarylenes. 1
3– exhibits a mixed emission from S2→S0 and S1'→S0, while 2
4– follows Kasha's rule displaying an S1'→S0 emission, notably, both anionic cycloarylenes display thermally activated delayed fluorescence (TADF) with lifetimes on the millisecond scale.
Abstract
Incorporation of non-benzoid rings into cycloarylenes significantly alters their molecular geometry and optical behavior. Recently, we synthesized two ferrocene-doped cycloarylenes, (CpFe)3-1 and (CpFe)4-2. However, the {FeCp} moieties in these architectures limited their optical properties. In this work, we report a reductive Fe─Cp bond cleavage approach that enables the removal of {FeCp} moieties efficiently, yielding two anionic cycloarylenes, 1
3– and 2
4–. Single crystal X-ray diffraction analysis reveals different structure deformation between two charged species including molecular symmetry and π-conjugation. Comprehensive spectroscopic analyses and theoretical calculations demonstrate that both 1
3– and 2
4– exhibit steady emission at 560 and 587 nm, respectively, with noticeable high quantum yields (59.70% and 84.99%). 1
3– violates Kasha's rule via a rare mixed emission from S2→S0 and S1'→S0, whereas 2
4– adheres to the conventional S1'→S0 decay. Furthermore, both compounds exhibit thermally activated delayed fluorescence (TADF) as the first example observed in cycloarylenes, with lifetimes reaching the millisecond scale. This work establishes alkali-metal-mediated reductive cleavage as an effective strategy to break Fe─Cp bond and provides new insight into the photophysical behavior of charged molecular nanocarbons, paving the way for the rational design of functional molecular materials.
31 Jul 16:28
by Qinze Zheng,
Ke Du,
Xian‐Kai Chen,
Yuxuan He,
Ge Gao,
Zhengyang Bin
A strategy for designing efficient narrowband red phosphorescent emitters is presented by orthogonal integration of boron–nitrogen multiple resonance (BN-MR) frameworks into tetradentate Pt(II) complexes. Theoretical calculations reveal that the BN-MR skeleton electronically perturbs the singlet excited state, thereby enhancing transition dipole moments and accelerating radiative decay rates.
Abstract
While considerable research efforts have been devoted to developing narrowband B,N-embedded multiple resonance (BN-MR) emitters, despite the formidable challenge, the design of efficient narrowband red phosphors has been overlooked. Herein, we present a design strategy that perpendicularly integrates BN-MR frameworks into a weakly emissive tetradentate Pt(II) complex to achieve efficient narrowband phosphors. Accordingly, we synthesized two novel emitters, BCzBN-PyPt and DPABN-PyPt. The optimized emitter BCzBN-PyPt exhibits exceptional performance characteristics: 1) narrowband red emission at 605 nm with a small full-width at half-maximum (FWHM) of 35 nm/0.118 eV in toluene, 2) a dramatically shortened exciton lifetime of 1.2 µs (compared to 7.6 µs for the parent complex PhPyPt), and 3) a remarkable photoluminescence quantum yield (Φ
PL) of 75% in doped films–representing a 4.4-fold enhancement over PhPyPt (Φ
PL = 17%). Theoretical investigations reveal that the BN-MR skeleton induces significant electronic perturbation of the singlet state, leading to enhanced transition dipole moments and accelerated radiative decay (k
r = 3.3 × 105 s−1 versus 0.1 × 105 s−1 for PhPyPt). In optimized OLED devices, BCzBN-PyPt achieves superior red narrowband electroluminescence with a maximum external quantum efficiency of 22.7%.
31 Jul 16:28
by Yuchao Liu,
Shengyu Li,
Jinyang Zhao,
Wei Ping,
Zhi Yang,
Lei Hua,
Junjie Wang,
Shian Ying,
Zhongjie Ren,
Shouke Yan
Oxygen-bridged cyclized boron-based multiple resonance thermally activated delayed fluorescence emitters have been constructed by engineering the intermolecular packing, which has led to near-unity photoluminescence yields and excellent reverse intersystem crossing being achieved via intermolecular donor–acceptor interactions in the solid state. A record high external quantum efficiency of 31.75% has been achieved with deep-blue narrowband emission.
Abstract
The development of high-efficiency and low-cost multi resonance thermally activated delayed fluorescence (MR-TADF) emitters especially in the deep-blue region is critically limited due to intrinsic excimer quenching of planar π-extended frameworks. Herein, a novel design strategy is reported for realizing high-efficiency oxygen-bridged cyclized boron-based MR-TADF emitters via engineering intermolecular packing mode. Three organic donor–acceptor (D–A) molecules with different molecular configurations are designed and synthesized, which can readily form modulated packing patterns with fastidiously regulating intermolecular charge transfer (CT) in crystalline states. Experimental and theoretical investigations expose that the intermolecular D–A packing modes could be formed in relatively planar molecular architecture, which cannot only fix the intermolecular CT excited-state configuration, but the multiple conversion channels of triplet excitons can also be involved synergistically to accelerate the spin-flip, and thus achieving near-unity PLQY and excellent reverse intersystem crossing rate of 6.7 × 105 s−1 in solid states. The optimized OLEDs devices achieve an attractive EQE value of 31.75%, which is at a record high for MR-TADF OLEDs with deep-blue emission. Our strategy boosts the luminescence efficiency of MR-TADF emitters through enabling the participation of multiple triplet states and the confined excited-state conformations induced by intermolecular CT interaction in aggregation state.
29 Jul 10:06
by Yeseo Lee,
Ha Yeon Kim,
Haeun Kwak,
Chae Yeong Park,
Subin Kwon,
Shinyoung Kim,
Eunji Lim,
Kyungsuk Jin,
Chang Seop Hong,
Weon‐Sik Chae,
Minhi Han,
Min Ju Cho,
Sungnam Park,
Dong Hoon Choi
A novel single-molecule exciplex host (TIO) is developed by linking p- and n-type units, offering efficient exciplex formation, good solubility, and film quality. Solution-processed OLEDs using this host show 31.06% EQE and 87% PLQY, outperforming conventional binary exciplex systems in efficiency and processability.
Abstract
Exciplexes that exhibit efficient reverse intersystem crossing have attracted considerable attention as host materials for high-performance organic light-emitting diodes (OLEDs). However, conventional binary exciplexes, composed of p- and n-type hosts and typically designed for vacuum deposition, are not suitable for solution-processed OLEDs owing to their low solubilities, poor film-forming properties, and phase-separation tendencies. In this study, the development of a novel “two-in-one” (TIO) is reported molecule that functions as a single-molecule exciplex host and is synthesized by covalently linking p- and n-type moieties via a non-conjugated spacer. First, this molecular design preserves the intrinsic electronic and photophysical properties of both the p- and n-type units while enabling efficient exciplex formation in thin films. Second, the TIO exciplex host exhibits excellent solubility, thermal stability, and film-forming properties, making it highly suitable for solution-processed OLEDs. Finally, a TIO exciplex host-based device with a green emitter delivers a higher external quantum efficiency (31.06%) than that of a binary exciplex host-based device. This improved device performance is attributable to the high photoluminescence quantum yield (87%) of the emitting layer and its excellent charge balance. This study demonstrates the potential of a single-molecule exciplex host for enhancing OLED efficiency while providing a simplified fabrication process.
26 Jul 08:29
by Masanori Uji,
Sakura Nakagawa,
Atsuko Nihonyanagi,
Daigo Miyajima,
Naoya Aizawa,
Nobuhiro Yanai
The TTA-UC from visible/UVA to UVB/C is demonstrated by combining a heptazine derivative with TIPS-benzene-based emitters. The heptazine derivative has a triplet energy level high enough to sensitize the emitters. The introduction of bulky tert-butyl substituents to the TIPS-benzene emitter is a simple and powerful strategy for enhancing the TTA-UC performance.
Abstract
UV energy generation via triplet-triplet annihilation-based photon upconversion (TTA-UC) plays a pivotal role in enabling high-energy photochemical reactions. However, generating UVB/UVC energy through TTA-UC remains a significant challenge. In this work, the TTA-UC from visible/UVA to UVB/UVC is demonstrated by combining (triisopropylsilyl)ethynyl benzene (TIPS-benzene)-based emitters with an organic sensitizer, a heptazine derivative. The heptazine derivative exhibits absorption in the visible/UVA region and has a triplet energy level high enough to sensitize the TIPS-benzene-based emitters. The introduction of bulky substituents into TIPS-benzene suppresses the deactivation pathways of the excited triplet state that compete with TTA, thereby enhancing the TTA-UC efficiency. This study demonstrates the direction of molecular design for the challenging generation of UVB/UVC energy.
26 Jul 08:28
by Yi‐Yun Chen,
Yu‐Cheng Kung,
Cheng‐Han Tsai,
Chun‐Kai Wang,
Dian Luo,
Yi‐Sheng Chen,
Shun‐Wei Liu,
Allen Chu‐Hsiang Hsu,
Wen‐Yi Hung,
Ken‐Tsung Wong
A stable and efficient near-infrared OLED with electroluminescence peaked at 834 nm has been achieved by employing an exciplex-forming donor:acceptor:spacer ternary blend with deep red emission as the host for accommodating a new benzobisthiadiazole (BBT)-based near-infrared emitter iCzPBBT.
Abstract
This study explores new ternary exciplex-forming systems comprising a deep red-emitting CPF:58p-QN blend and various ratios of spacer TPF to optimize donor-acceptor interactions and exciplex characteristics. Time-resolved photoluminescence reveals delayed fluorescence of CPF:58p-QN:TPF blends, confirming the thermally activated delayed fluorescence (TADF) characters. By introducing different ratios of TPF, a progressive blueshift emission wavelength ranging from 696 nm (without TPF) to 659 nm (50 wt.% TPF) is observed. Notably, device A2, featuring CPF:58p-QN:TPF (2:2:1) blend as emitting layer, achieves a maximum external quantum efficiency (EQEmax) of 2.13% with the electroluminescent peak (EL λmax) centered at 672 nm. Moreover, a fluorescence emitter iCzPBBT is introduced as a dopant to realize a near-infrared (NIR) emissive device. Device B2, utilizing the CPF:58p-QN:TPF (2:2:1) blend as host doped with 5 wt.% iCzPBBT, exhibits an EQEmax of 1.35% (EL λmax = 848 nm), demonstrating effective energy transfer from exciplex to NIR dopant. Device C2 with a reduced amount of iCzPBBT (2 wt.%) to mitigate concentration quenching achieves an EQEmax of 1.72% (EL λmax = 834 nm) and good stability (LT90 > 88 h under a constant current density of 0.6 mA cm⁻2). This study underscores the potential of a ternary exciplex-forming system as a promising host for NIR OLED applications.
26 Jul 08:27
by Tuul Tsagaantsooj,
Xun Tang,
Takuji Hatakeyama,
Chihaya Adachi
Efficient light amplification depends on balancing oscillator strength, spectral overlap, and vibronic emission. While rigid multi-resonance materials boost oscillator strength, their small Stokes shifts induce self-absorption. Enhancing the vibronic sideband can offset this by aiding light amplification. Conversely, large Stokes shifts (e.g., D–A systems like PXZN-B) minimize reabsorption, enabling robust amplification despite their moderate oscillator strength.
Abstract
Thermally activated delayed fluorescence (TADF) molecules offer significant promise for organic laser applications due to their potential triplet harvesting. Encouragingly, localized charge-transfer characteristics within rigid skeletons, such as multiple-resonance (MR) effects and locked donor–acceptor (D–A) interactions, are particularly attractive as they enable both large oscillator strengths and TADF properties. In this study, representative boron/nitrogen (B/N)-containing TADF molecules are investigated to reveal the crucial role of Stokes shifts in tuning absorption–emission overlap. This overlap influences self-absorption losses and ultimately reorganizes the transition mode for lasing output. Notably, although ν-DABNA exhibits the highest stimulated emission cross-section coefficient (σem), it results in lasing from the 0−1 vibronic transition with the highest lasing threshold (12.0 µJ cm−2) owing to its strong steady-state and excited-state absorption losses. In contrast, PXZN-B, featuring a locked D–A skeleton with a smaller σem, achieves a lower lasing threshold of 3.9 µJ cm−2 by leveraging a larger Stokes shift, which minimizes reabsorption losses and facilitates efficient light amplification at the dominant 0−0 transition. These findings highlight the importance of balancing oscillator strength enhancement with favorable spectral separation to modulate the ideal transition mode for efficient organic lasing.
26 Jul 08:27
by Shengnan Wang,
Shuyao He,
Hao Huang,
Runjie Ding,
Lifen Xia,
Yuchao Liu,
Shian Ying,
Dongge Ma,
Shouke Yan
The planarized excited state conformation, induced by intramolecular non-covalent interactions, endows the ultraviolet fluorophore with a high radiative rate and a hybridized local and charge-transfer state characteristic, resulting in external quantum efficiencies of 8.84% and 8.15% at 500 and 1000 cd m⁻2, respectively, with color coordinates of (0.166, 0.025) in the device.
Abstract
The serious efficiency roll-off in the ultraviolet organic light-emitting diodes (UV-OLEDs) limits their potential for advanced applications under high-brightness conditions. In this work, two high-performance asymmetric donor-acceptor-donor’ type tetrafluorobenzene-bridged fluorophores (mPIoCZ4F and mPImCZ4F) are developed with a hybridized local and charge-transfer state characteristic. The planarized excited state conformation induced by intramolecular non-covalent interactions endows the emitters with high radiative rate and fluorescence efficiency, while simultaneously preserving effective UV emission. The doped devices utilizing mPIoCZ4F and mPImCZ4F as emitters exhibit high color purity with electroluminescence peaks of 391 and 389 nm, and full-width at half-maximums of 41 and 39 nm, as well as impressive external quantum efficiencies (EQEs) exceeding 8.3%. Due to the multi-channel high-lying reverse intersystem crossing and limited intersystem crossing, mPIoCZ4F-based device exhibits a more excellent EQE of 8.91%, and remains 8.84% and 8.15% at 500 and 1000 cd m−2, indicating a minimal efficiency roll-off. Such outstanding performance provides the possibility for UV-OLEDs to be utilized in high-brightness applications.
25 Jul 10:50
by Tao Jiang, Jiayi Qin, Jieyu Lin, Xiaoxuan Lin, Wei Liu, Zhixin Xie, Carl Redshaw, Zujin Zhao, and Xing Feng
ACS Applied Materials & Interfaces
DOI: 10.1021/acsami.5c08493
25 Jul 09:55
J. Mater. Chem. C, 2025, 13,18092-18100
DOI: 10.1039/D5TC02210J, Paper
Yili He, Haoting Yang, Yuanchun Yue, Xiangqing Gan, Shuai Xiao, Xian Chen, Shaobiao Zhu, Danrui Wan, Renze He, Han Si, Guoyun Meng, Pangkuan Chen, Junqiao Ding
A π-extended tetracoordinate boron [8]helicene, Hel-BNN, was synthesized, exhibiting efficient TADF and pronounced chiroptical properties. A sensitized OLED using it exhibited an EQEmax of 21.9% and displayed circularly polarized electroluminescence.
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25 Jul 09:51
by Li Wan,
Eunkyung Cho,
Rui Zhang,
Theis Brock‐Nannestad,
Zhaohui Wang,
Jean‐Luc Brédas,
Veaceslav Coropceanu,
Feng Gao
A fundamental chiroptical response amplification mechanism is revealed to massively enhance molecular helicene chiral emitters. The luminescent dissymmetry factor of the helicene emitter is amplified by 133 times through excited-state hybridization with a polymeric chiral environment. The amplification mechanism does not rely on a specific energy transfer process, therefore offering new paths for the design of chiral emissive systems.
Abstract
Circularly polarized (CP) light is extensively used in various fields such as asymmetrical synthesis, sensing, and advanced displays. Consequently, significant efforts have been made to develop chiral materials that intrinsically emit CP light with a large dissymmetry factor (g-factor). It is widely considered that the dissymmetry factor for individual organic emitters, due to the amplitude offset between their electric and magnetic transition dipole moments, is limited to ≈10−2, which is inadequate for practical applications. Recent efforts to enhance CP light emission have therefore focused on amplifying the dissymmetry of circularly polarized luminescence (CPL), often via specific energy transfer processes. Here, a fundamental mechanism is discovered – excited-state hybridization, which amplifies CPL through excitonic coupling without relying on energy transfer processes. Through this wavefunction hybridization, both the amplitude and sign of the rotatory strength related to the molecular emitter's electronic transition are modified to align with its chiral environment, remarkably boosting the CP luminescence from an intrinsic dissymmetry factor of −10−3 up to +0.40. This breakthrough allows for more versatile design strategies for chiral emissive systems, moving beyond designs limited to energy transfer processes and paving the way for new approaches to achieve strong CP emissive materials.
23 Jul 11:52
by Yufu Sun,
Xi‐Feng Fu,
Chen‐Lu Hou,
Ting‐Ting Lin,
Dong‐Hai Zhang,
Jin Liu,
Jia‐Xuan Hu,
Fu‐Lin Lin,
Liang Zhou,
Lingyi Meng,
Xu‐Lin Chen,
Can‐Zhong Lu
Highly efficient ultra-deep-blue TADF emitters were developed through the construction of multipathway charge transfer characteristics. OLEDs employing the optimized molecule as the terminal emitter and as a sensitizer exhibit high-performance deep-blue electroluminescence, achieving EQEs of up to 24.7% and 37.9%, with corresponding CIE-y values of 0.038 and 0.106, respectively.
Abstract
BT.2020-compliant deep-blue emitters for organic light-emitting diodes (OLEDs) are in high demand to achieve a wide color gamut for ultrahigh-definition displays. Herein, we report deep-blue thermally activated delayed fluorescent emitters featuring a unique donor1-donor2-acceptor (D1-D2-A) molecular configuration in which C1-N linked carbazole derivatives serve as dual-function donors and an oxygen-bridged triarylboron unit acts as the acceptor. The new design strategy focuses on constructing excited states with multipathway charge transfer characteristics—including multiresonance, through-bond, and through-space charge transfer—by precisely tuning the relative electron-donating strengths of the D1 and D2 units. Experimental and theoretical studies reveal that the optimized emitter, BO-BTC, achieves a well-balanced trade-off among emission efficiency, color purity, singlet–triplet energy gap, and horizontal dipole orientation ratio. Consequently, OLEDs using BO-BTC as the terminal emitter or as the sensitizer for ν-DABNA achieve high-efficiency deep-blue electroluminescence, with external quantum efficiencies of up to 24.7% and 37.9%, Commission Internationale de l’Éclairage-y values of 0.038 and 0.106, respectively.
17 Jul 09:53
Chem. Sci., 2025, 16,14478-14484
DOI: 10.1039/D5SC03458B, Edge Article
Open Access
Li Zhang, Chenglin Ma, Xin Wang, Yannan Zhou, Jingru Song, Mizhen Sun, Qikun Sun, Shi-Tong Zhang, Wenjun Yang, Shanfeng Xue
Simple-structured NUV molecule with a benzonitrile acceptor achieves rapid and balanced carrier mobility. The doped OLED shows high efficiency and superior color purity, leading similar devices based on the HLCT mechanism (400 nm ≤ λEL ≤ 410 nm).
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17 Jul 09:52
by Gui-Xin Yan,
Er-Xia Chen,
Jin-Xia Yang,
Jian Zhang,
Qipu Lin
Enantiomeric tin-oxo clusters form helical supramolecular matrices through directional intermolecular interactions, enabling efficient transfer of optical handedness to encapsulated non-chiral fluorophores via spatial confinement. These assemblies exhibit tunable circularly polarized luminescence (CPL) emissions.
Abstract
Tin-oxo clusters, characterized by their well-defined chemical compositions and architectures, are multi-metal aggregates composed of Sn-oxide cores and surface ligands. Chirality, a fundamental characteristic governing biological recognition and signal transduction, remains underexplored in stannate clusters compared to extensively studied precious metal clusters. Herein, three enantiomeric pairs of chiral tin-oxo clusters were constructed using axially chiral 1,1′-bi-2-naphthol (BINOL) ligands. Structural analyses revealed supramolecular helical assemblies mediated by directional C─H···π interactions, while circular dichroism (CD) spectroscopy confirmed their intrinsic chirality. Through in situ doping engineering, non-chiral fluorophores with distinct emission profiles were incorporated during chiral cluster crystallization, yielding composite materials exhibiting circularly polarized luminescence (CPL). The optimized system achieved a maximum dissymmetry factor (g
lum) of 1.5 × 10−2. Mechanistic studies established that the spiral packing of the tin-oxo clusters facilitates stereochemical information transfer to the dyes via the spatial confinement effect. This supramolecular chirality induction paradigm offers new insights into the rational design of multifunctional optical materials.
12 Jul 20:11
J. Mater. Chem. C, 2025, 13,17094-17100
DOI: 10.1039/D5TC01905B, Paper
Jianping Zhou, Hai Zhang, Qi Wang, Danrui Wan, Guoyun Meng, Dongdong Zhang, Lian Duan
A novel narrowband multi-resonance emitter obtained by incorporating B–N covalent bonds and extending π-conjugation via a simplified lithium-free one-pot borylation reaction achieved a redshifted sky-blue emission at 484 nm with a FWHM of 19 nm.
The content of this RSS Feed (c) The Royal Society of Chemistry
11 Jul 20:30
Chem. Sci., 2025, 16,15256-15264
DOI: 10.1039/D5SC03560K, Edge Article
Open Access
Sen Wu, Dongyang Chen, Mathilde Seinfeld, Aidan P. McKay, David B. Cordes, Xiaohong Zhang, Eli Zysman-Colman
A three-boron doped MR-TADF emitter, TBDON, was developed and shows fast reverse intersystem crossing and bright, blue narrowband emission. The device with TBDON achieved a maximum external quantum efficiency of 28.1% and low efficiency roll-off.
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11 Jul 20:15
by Zheng Zhang, Weizhe Hu, Zhibo Liu, Yusuke Tsutsui, Yasujiro Murata, Shu Seki, and Takashi Hirose
Journal of the American Chemical Society
DOI: 10.1021/jacs.5c08688
11 Jul 20:14
by Xiang Wang, Xiaowan Han, Xiaoyuan Tian, Hosoowi Lee, Caihong Xiang, Chaorui Wang, Liang Luo, Hai-Yu Hu, Guangle Niu, and Juyoung Yoon
Journal of the American Chemical Society
DOI: 10.1021/jacs.5c10005
11 Jul 14:07
J. Mater. Chem. C, 2025, 13,16452-16459
DOI: 10.1039/D5TC02048D, Paper
Xia Wang, Chuanxin Liao, Xianggao Li, HongLi Liu, Shirong Wang
Three thermally cross-linkable deep-blue emitters were synthesized and full-solution-processed OLEDs all exhibited deep-blue emissions with peaks at 440, 443, and 444 nm, wherein the device based on V-SAFCz achieved an EQEmax of 1.91%.
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