Simultaneously realizing high internal quantum efficiency (IQE) and light outcoupling efficiency (LOE) in OLEDs solely depending on molecular engineering has never been achieved. Here, we design three OLED emitters (DCzPDO, DPhCzPDO, and DPAPDO), all comprising 3-hydroxypropenone and β-diketone tautomers. One prominent feature of them is hot-exciton emission enabled by high-lying reverse intersystem crossing (hRISC), hence significantly improving material electroluminescence. Interestingly, in DPAPDO, both isomers exhibit hot-exciton fluorescence, while in the other two materials, only the β-diketone tautomer demonstrates this feature. On the other hand, these materials possess different degrees of preferential transition-dipole-moment alignment, promoting light extraction in OLEDs. Furthermore, their molecules tend to self-assemble along 1D directions, inducing a quasi-parallel V-shaped nanogroove, significantly enhancing light outcoupling in devices. Among them, DPAPDO achieves the highest device performance, reaching a maximum external quantum efficiency (EQE) of 23.7%. DPAPDO comprises the highest concentration of β-diketone isomer, with both isomers facilitating effective hRISC transitions, leading to a near unity IQE of luminescence. Additionally, DPAPDO displays the highest-quality film nanostructure and moderate horizontal dipole ratio, thereby achieving a high LOE of 57%. All these factors account for its high OLED performance. The synergistic interplay between electroluminescence and molecular/supramolecular structures paves the way for cost-effective, scalable, high-efficiency OLEDs.

Traditional white organic light-emitting diodes (WOLEDs) often rely on mechanism of incomplete energy transfer, which generally necessitate extremely low doping concentrations for low-energy emitters. This poses significant challenges in device fabrication reproducibility and color coordinate consistency. In this work, we developed a hot exciton yellow-emitting excited state intramolecular proton transfer (ESIPT) fluorophore, T4AC, featuring a large Stokes shift. The material achieves a high exciton utilization efficiency of up to 88.8 %, via highenergy-level reverse intersystem crossing (hRISC). By co-doping T4AC with a thermally activated delayed fluorescence (TADF) blue emitter, DMAc-MPM, we realized highly efficient and reproducible bluish WOLEDs employing a single emitting layer with complementary-color emissions. Minimal spectral overlap effectively suppressed energy transfer, thus ensuring independent triplet harvesting via hot exciton mechanism in T4AC and the TADF process in DMAc-MPM, respectively. The resulting device exhibits color stable and high-efficiency cold white emission, achieving maximum external quantum efficiency (EQE) of 11.50 % and current efficiency (CE) of 27.74 cd A- 1. More importantly, these bluish WOLEDs demonstrated excellent reproducibility across multiple batches, with small EQE variations within 11.15 % +/- 0.62 % and CIE coordinate fluctuations confined to a narrow range of (0.181 +/- 0.004, 0.351 +/- 0.030). This study presents a viable strategy for the development of simple-structured, highly efficient, and reproducibly fabricated cold WOLEDs.

A photoredox-catalyzed trifluoromethylation/cyclization of N-allylbenzimidazoles using eosin Y-Na2 under visible light affords trifluoromethylated benzimidazo-fused heterocycles. Two complementary protocols are established: Method A employs Togni's II under nitrogen-the first example of this catalyst-reagent combination; Method B utilizes the more economical Langlois reagent under air. The reaction features broad substrate scope and enables unprecedented seven-membered ring formation.

Organic thermofluorochromic materials (TFMs) hold great promise for large-area, flexible thermal indication and anti-counterfeiting, yet their utility at high temperatures is severely hindered by poor solid-state thermofluorochromism, inaccurate temperature readout, and severe thermal quenching. Herein, we report three heat-resistant TFM films based on distinct thermochromic mechanisms: stepwise stacking modulation with delayed fluorescence and nonadiabatic vibrational coupling (tBu-DHPPO), high-barrier tautomerization (HBT-TPA), and suppression of energy transfer in their hybrids (tBu-DHPPO/HBT-TPA). Leveraging their enhanced thermal robustness, these TFM films deliver outstanding thermometric performance across a wide temperature range (20–300 °C), exhibiting high maximum relative sensitivities of 2.46, 5.87 and 2.49% °C−1 above 150 °C and remarkable optimal temperature resolutions of 0.05–1.07, 0.21–1.26, and 0.05–1.01 °C, respectively. By integrating these three cross-validated TFMs with machine learning, we established a smartphone-based optical readout platform that achieves ultrahigh-accuracy temperature prediction, with a near-perfect coefficient of determination (R2) of 0.99997 and a low root-mean-square error (RMSE) of 0.4682 °C. Furthermore, these TFM films enable naked-eye, non-invasive thermal imaging, patterning, and anti-counterfeiting encryption under ambient conditions. These findings demonstrate a new strategy that bridges multiple robust thermofluorochromic films and accessible machine learning, paving the way for next-generation intelligent thermal reading and anti-counterfeiting systems.

Red-emitting materials have significantly advanced the development of materials for OLEDs and bioimaging. However, traditional red dyes often suffer from the 5 % external quantum efficiency (EQE) limit and aggregation-caused quenching (ACQ), which impede their practical applications. Herein, two red-emitting materials, TPA-QP and Cz-Ph-QP were designed and synthesized with donor-acceptor (D-A) structures. The ratio of localized π-conjugation to intramolecular charge transfer components was rationally adjusted due to the different spatial configurations of the donor units. Both emitters exhibited hybridized local and charge transfer (HLCT) characteristics and the higher planarity of the TPA-QP molecular structure enhanced π-conjugation and facilitated effective hybridization between the locally excited (LE) and charge transfer (CT), resulting in deep-red (DR) emission at 680 nm and high photoluminescence quantum yields of 15.6 %. Furthermore, TPA-QP-based OLED demonstrated emission closer to the standard saturated red (λ = 657 nm, CIE coordinates of (0.65, 0.33)) with an excellent maximum EQE of 6.47 % and low efficiency roll-off. Additionally, the fabricated nanoparticles (TQ NPs) showed deep-red emission (λ = 682 nm) and were successfully applied in cellular imaging. The results provide deeper insights into the effects of spatial configuration changes on promoting the luminescence performance of the long-wavelength HLCT molecules.

The development of high-efficiency deep blue organic light emitting diode (OLED) emitters is critical for display and solid-state lighting applications. However, achieving optimal performance is challenging due to conflicts between color purity, photoluminescence intensity, and exciton utilization efficiency. In this study, two deep blue emitters based on pyrenyl phosphine oxides are synthesized by modifying a carbazole substituent, aiming to achieve a balance between moderate emission bathochromism, high photoluminescence quantum yield (PLQY), and favorable transition characteristics. Additional exciton harvesting via high-lying reverse intersystem crossing (hRISC) markedly enhances the efficiency of OLED devices. The maximum external quantum efficiencies (EQEs) achieve 11.23% and 8.14%, with Commission International de L'Eclairage (CIE) coordinates of (0.15, 0.07) and (0.15, 0.12), respectively. The presence of hRISC transitions also contributes to significant heat resistance to the devices, with a 22- and 71-fold enhancement in electroluminescence (EL) in the deep blue and white OLEDs, respectively, as the temperature increases from room temperature to 500 and 450 K. This study demonstrates the strong potential for these emitters in energy-saving OLED applications suitable for extreme environments.

Efficient excited state intramolecular proton transfer (ESIPT) OLED emitters are critical for the development of cost-effective and color-stable WOLEDs due to their significant Stokes shifts, which minimizes spectral overlap. In this research, a yellow-emitting ESIPT fluorophore, HBT-PA, has been demonstrated to achieve high-efficiency OLEDs with a maximum external quantum efficiency (EQE) surpassing 5% and a current efficiency (CE) of 22.20 cd A-1. This performance is attributed to the effective utilization of excitons by the S2 singlet reservoir in the keto tautomer, enabling the harvesting of triplet excitons through multi-channel, highly efficient high-lying reverse intersystem crossing (hRISC), which is predominantly barrierless and characterized by substantial spin-orbit coupling (SOC) matrix elements of 6.7-10.9 cm-1. Complementary-color WOLEDs, exhibiting remarkable color stability and performance, were fabricated based on the fluorophore's exceptionally large Stokes shift. These WOLEDs demonstrated maximum EQE and CE values of 13.57% and 16.84 cd A-1, respectively. This study highlights the significant potential of HBT-PA for low-cost and large-scale production of energy-efficient WOLEDs.

Minimizing the spectrum overlaps of energy transfer (ET) is necessary but not sufficient for achieving high-sensitivity film thermosensing. Herein we have designed two blue emitters of DBA-BPAc and Z-DBABH exhibiting blue and bluish-green emissions, respectively, to hybridize with the red-emitting Ir(MDQ)2(acac). Compared with Z-DBABH, DBA-BPAc shows a larger spectrum overlap of ET and a relatively smaller discrepancy in fluorescence thermal decay, while its emission spectrum displays a much smaller overlap with that of Ir(MDQ)2(acac). The dual minimization of spectrum overlap of ET and emissions results in its superior ratiometric film thermosensing of the DBA-BPAc film in wide-range and high-temperature regions. The DBA-BPAc/Ir(MDQ)2(acac) film exhibits a maximum relative sensitivity (Sr) of 3.36% °C−1 at 166 °C, exceeding 0.43% °C−1 in 50–265 °C. In comparison, the Z-DBABH/Ir(MDQ)2(acac) system displays a reliable but relatively lower performance, with a maximum Sr of 1.92% °C−1 (at 300 °C). The temperature resolution remains below 2.06 °C throughout the entire temperature range (20–300 °C), achieving a best value of 0.60 °C at 180 °C. Notably, both films display distinct naked-eye color transitions with temperature changes, enabling multi-level anti-counterfeiting applications. This work provides new insights for designing high-performance thermometers.

Hot exciton organic light-emitting diode (OLED) emitters can balance the high performance of a device and reduce efficiency roll-off by fast reverse intersystem crossing from high-lying triplets (hRISC). In this study, an excited-state intramolecular proton transfer (ESIPT) fluorophore of 2-(benzo[d]thiazol-2-yl)-4-(pyren-1-yl)phenol (PyHBT) with the typical characteristic properties of a hot exciton is developed. With high efficiency of utilization of the exciton (91%), its yellow OLED exhibited high external quantum efficiency (EQE) of 5.6%, current efficiency (CE) of 16.8 cd A-1 , and power efficiency (PE) of 17.3 lm W-1 . The performance of the yellow emissive "hot exciton" ESIPT fluorophores is among the highest recorded. Due to the large Stokes shift of the ESIPT emitter, non-energy-transferred high-performance white OLEDs (WOLEDs) are developed, which are reproducible and highly efficient. This is possible because of the independent harvesting of most of the triplets in both complementary-color emitters without the interference of energy transfer. The PyHBT-based WOLEDs exhibit a maximum EQE of 14.3% and CE of 41.1 cd A-1 , which facilitates the high-yield mass production of inexpensive WOLEDs.

Organic ratiometric light-emitting thermosensors have great advantages such as large-area thermal mapping, fast response and high resolution. However, thermally-quenched luminescence and interference caused by energy transfer largely diminishes their sensitivities. In this work, we have developed a heat-resistant organic yellow-emitting Excited State Intramolecular Proton Transfer (ESIPT) fluorophore to be used as monochromic and ratiometric film thermometer for high-temperature sensing. This ratiometric film thermosensor exhibits higher sensing abilities with widened detection range for high-temperature sensing, with the relative sensitivity (S-r) higher than 0.5 % K-1 in temperature range from 40 similar to 160 degrees C to 40 similar to 300 degrees C. The maximum S-r of the hybrid film reaches as high as 2.5 % K-1 at 220 degrees C. Applications in naked-eye thermal mapping and double encryption have also been demonstrated.

Abstract Compliant and large‐area high‐temperature gradient sensing is essential for scientific and industrial applications but remains a big challenge. Although organic luminophores have intrinsic advantages of flexibility and solution processability, they generally suffer from significant emission quenching at high temperatures due to thermally facilitated nonradiative decay. Herein, a heat‐resistant blue emitter of C3 based on triarylphosphine oxide has been developed, due to the thermal population of the higher emissive state from its lowest excited state. Based on this, hybridization of C3 with a faster thermally‐deactivated yellow dye of T4AC which exhibits a large Stokes shift enables blocking of energy transfer and independent thermal response of the two respective emitters. Thus, sensitive ratiometric film thermometers for high‐temperature sensing can be constructed. The relative sensitivity (Sr) reaches 1.27%°C−1 at 128 °C and the temperature resolution is < 0.77 °C in a wide sensing range of 20–240°C. Moreover, naked‐eye thermal mapping and multiple anti‐counterfeiting of these ratiometric films have also been demonstrated.

Conventional fluorescent WOLEDs generate white light by incomplete energy transfer but face challenges in precisely controlling energy transfer and improving device efficiency due to the maximal utilization of 25% singlet excitons. In this study, two newly developed excited-state intramolecular proton transfer (ESIPT) fluorophores emit orange and white light. These fluorophores utilize excitons efficiently (70-88%) via high-level reverse intersystem crossing (hRISC) exclusively in the keto form and in both isomers (enol/keto), respectively. The white emitter, with comparable dual emissions, enables the fabrication of color-stable cold-white single-emitter OLED with a CRI of 74 and maximum external quantum efficiency (EQE) of up to 5.60%. The orange emitter, when combined with a sky-blue TADF fluorophore, creates non-energy-transferred single-emitting-layer (SML) high-performance cold- and pure-white WOLEDs with CIE coordinates of (0.26, 0.35) and (0.32, 0.32), and maximum EQEs of 13.34% and 9.66%, respectively. Importantly, these complementary-color WOLEDs demonstrate high reproducibility, offering advantages for industrial batch fabrication. Thus, this research presents a route to achieve cost-effective mass production of simple-structured and high-efficiency WOLEDs.

High‐contrast and stably visualized ambient or luminescent color‐switching can be achieved by thermal‐induced non‐invasive chemical reaction for naked‐eye threshold temperature indication. The clear and visible output signal of these indicators arises from the large absorption/emission spectral changes upon heating. However, such chemical reactions are difficult to realize in solid‐state, especially in the high‐temperature region. Herein, a series of naked‐eye high‐temperature threshold film indicators have been developed based on the solid‐state in situ thermal decomposition reaction of difluoroboron β ‐diketonate derivative. These thermosensitive films feature three high‐contrast visible outputs of ambient thermochromism, fluorescence color change, and luminescence ON/OFF switching, which can be easily detected with the naked eye. The PR‐PS film of (E)‐4‐(2‐(6‐bromopyren‐1‐yl)vinyl)‐2,2‐difluoro‐6‐phenyl‐2H‐1 λ 3 ,3,2 λ 4 ‐dioxaborinine (PR) doped in polystyrene (PS) polymer matrix achieved high sensitivities related to change of ratiometric luminescence and fluorescence intensity up to 230%°C −1 and 1.85%°C −1 , respectively. Furthermore, the polymer matrix with different glass transition temperatures enables programmable tuning of threshold temperature from 120 to 180 °C. These thermosensitive films show clear and high‐contrast color changes and emission turn‐off in real‐time with consistent air stability, high photostability, and waterproofing property. This shows considerable potential in outdoor robust high‐temperature threshold sensing and information storage.

Red emitting materials are the key to development of organic light-emitting diodes (OLEDs) and bioimaging, but limited by the energy gap law and aggregation-caused quenching (ACQ), impeding their applications. Herein, two red emitters TPA-QxPy and Cz-Ph-QxPy were designed and synthesized with aggregation-induced emission (AIE) characteristics. TPA-QxPy had a strong charge transfer (CT) state, while due to the different spatial configurations of the donor units, intramolecular hydrogen bonds were formed in the Cz-Ph-QxPy, enabling the locally excited (LE) state to be incorporated into CT emissive state to form hybridized local and charge-transfer (HLCT) state. The results demonstrated that the higher planarity of the Cz-Ph-QxPy enhanced the pi-conjugation and hybridization between the CT and LE, showing a red emission at 600 nm and a high fluorescence quantum yield of (phi PL) 30.8% in film. Cz-Ph-QxPy-based OLED achieved highly efficient red emission with external quantum efficiency (EQE) of 7.56% at 580 nm. Moreover, benefiting from AIE characteristics, the fabricated TQx NPs and CQx NPs with near-infrared (NIR)/red emission showed high photostability and biocompatibility and were successfully used for cellular imaging. This work provides new insights for promoting the luminescence performance of red emitting materials with HLCT state by spatial configuration changes.

Fine tuning the energy gaps of red emitters and promoting the fluorescence efficiencies are especially highly desired considering their specific applications. Herein, by varying the molecular symmetry from D-A-D to D-A structures, the red fluorescent emitters with triphenylamine (TPA) donor and 2,3-dicyanopyrazino phenanthrene (DCPP) acceptor realized increased fluorescence quantum yield (phi PL) from 2TPA-DCPP to TPA-DCPP due to the decreased non-radiative paths. Moreover, fine control of the emitting color from orange to red and then to deep -red was achieved depending on the intermolecular packing patterns of TPA-DCPP in the aggregation state. Taking the advantages, TPA-DCPP-based OLED exhibited red emission (lambda = 640 nm, CIE coordinate of (0.62, 0.38)) with an excellent maximum EQE of 8.30%. The TPA-DCPP@F-127 nanoparticles showed deep-red emission (lambda = 684 nm) and were successfully used for cellular imaging of Hela cells. Our results demonstrated that "the simpler, the better" strategy may be feasible to construct D-A structured red emitters with high effi-ciencies for diverse applications.

Energy transfer is usually applied in ratiometric thermometry, but it often decreases sensitivities due to much reduced distinguishment in the thermal responses of two different‐colored emitters. Herein, a feasible strategy to restrain energy transfer is utilized for achieving sensitive high‐temperature detection, simply by increasing the dopant concentration to induce microphase separation. Atomic force microscopy phase images reveal that this phase separation becomes dominant when the doping ratio reaches above 40%. This results in suppression of energy transfer, which is evidenced by systematic photophysical investigations. On this basis, by using heat‐resistant emitters, a series of inexpensive and easily prepared solid‐film organic high‐temperature ratiometric thermometers are developed. They exhibit a broad eye‐detective sensing range of 102–236 °C with the relative sensitivity ( S r ) higher than 0.5% K −1 and the maximum temperature resolution attaining 0.39 K. Good reversibility and stability are also demonstrated in ambient atmosphere.

The development of organic thermosensitive fluorophores for use in heat‐resistant organic light emitting diodes (OLEDs) and large‐area and flexible high‐temperature sensing remains challenging due to the susceptibility of such materials to thermally facilitated nonradiative decay. A series of “hot exciton” materials (“C1” and “C2”) based on pyrrole‐substituted triarylphosphine oxides that exhibit high heat resistance have been developed. At a temperature of 260 °C, the films retain 42% (C1) and 29% (C2) of their room temperature fluorescence. This is thanks to thermally facilitated reverse intersystem crossing (RISC) from a high‐lying triplet to a singlet state. By combining the novel fluorophores with a yellow emitter with an extremely large Stokes shift, flexible and large‐area ratiometric film thermometers are fabricated that demonstrate naked‐eye high‐temperature sensing. The relative sensitivity, S r , of the film thermometer is higher than 1% K –1 in the high‐temperature region (393 to 470 K), with the maximum S r reaching 1.26% K −1 at 430 K. Using these blue emitters, heat‐resistant cyan and white OLEDs are also fabricated. With thermally populated singlets and nearly 100% exciton harvesting via fast RISC, the C1‐based cyan OLED exhibits a nearly 12‐fold enhancement in electroluminescence on heating from room temperature to 530 K, while the corresponding white OLED displays a 5.7‐fold electroluminescence enhancement.

Threshold temperature sensors are crucial for recording the thermal histories of environments under different scenarios. However, most organic threshold thermometers are not suitable for high‐temperature indication due to significant thermo‐facilitated emission quenching. Here, a series of ratiometric luminescent high‐temperature threshold organic film indicators have been realized by synergetic effects of intramolecular local excited to charge transfer states and disaggregation from excimer to monomer. Varying the polymer matrixes with different glass transition temperatures effectively tunes the threshold sensing temperatures. More importantly, the wide sensing span of the high‐temperature region enables the single‐sample films (in one kind of polymer matrix) to achieve multiple temperature threshold indications, directed only by multiple naked‐eye emission color changes. These drop‐casting organic film thermometers indicate great potential in robust and low‐cost outdoor applications, as well as large‐area and flexible threshold temperature sensing.

Pillar[n]arene-based supramolecular polymers have attracted great interest because of their tunable morphologies and external stimuli responsiveness. However, most of the investigations of supramolecular polymers previously reported were focused on their formation and transformation, and investigations on their applications are rare. Herein, we designed and prepared hybrid polymeric materials by incorporating Pd nanoparticles into a supramolecular polymer, constructed from a pillar[5]arene dimer and a three-arm guest. The obtained hybrid polymer was fully characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, scanning electron microscopy-energy-dispersive X-ray mapping, and X-ray diffraction technologies. Importantly, the hybrid supramolecular polymeric materials exhibited desirable catalytic activity for reductions of toxic nitroaromatics and C-C bond-forming Suzuki-Miyaura reaction in aqueous solution.

Amorphous thin films from solution‐processable semiconductors are key materials for low‐cost and large area optoelectronics. Design rules toward novel amorphous compounds with outstanding light emission and light amplification properties require understanding of the intimate relation between chemical and electronic structure. Here, a series of compounds with tunable electronic transition characters of the lowest excited state, from local excited (LE), hybrid local charge‐transfer (HLCT) to charge‐transfer (CT) character is delicately designed. By deploying a combination of computational calculations and femtosecond‐transient absorption experiments, it is shown that pure LE states strongly coupled to high wavenumber vibrational modes favor to form a few dominant discrete vibrational levels and are essential for optical gain, whereas HLCT or CT states are preferably coupled to low frequency vibrational modes and form a large number of consecutive vibrational levels which lead to broad excited‐state absorption overwhelming stimulated emission. The results provide guidelines for the rational design of efficient organic laser materials.