Rapid advances in organic solar cells (OSCs) have attracted significant attention in recent years, especially after the emergence of Y6 and its derivatives. Despite the remarkable progress that has been successfully achieved, challenges such as low power conversion efficiency (PCE) and unsatisfactory stability remain. While there is considerable potential in the application of deuterated small-molecule electron acceptors to address these two issues, there is also a lack of consensus in the research outcomes, which suggests that further investigation is required. To further investigate deuterium-substituted small-molecule electron acceptors, the dideuterated analogue of Y6 (Y6-d2) was synthesized with the aim of simultaneously enhancing the PCE and stability of OSCs. Y6-d2 exhibits a more compact crystal structure while maintaining the same energy levels and absorption characteristics as those of Y6. This gives rise to larger phase separation in the blend film with PM6 and enhances the resultant photovoltaic performance of the device. While exhibiting comparable open-circuit voltage (V OC, 0.843 V), the PM6:Y6-d2-based device demonstrates superior performance with an intensively improved short-circuit current density (J SC, 28.48 mA cm-2) and fill factor (FF, 81.3%). These improvements, in turn, significantly boost the device's PCE up to 19.5% and long-term stability of its initial efficiency over 96% after 1200 h storage, surpassing the 18.86% and 84% of the benchmark PM6:Y6 device, confirming the effectiveness of dieuterated Y6 for enhancing PCE and improving stability for OSCs.

Pentazolate salts are promising high-energy-density materials yet remain hindered by extreme hygroscopicity and sensitivity. Here, a 1:1 cocrystal of NH3OH+N5 - with 18-crown-6 (18C6) prepared via slow evaporation, fully characterized by single-crystal and powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), and non-covalent-interaction (NCI) analysis. The structure reveals that the cocrystal is driven by strong N-H...O hydrogen bonds between NH3OH+ and 18C6. NCI partitioning shows that N-H...N contacts dominate the material (63.9 % of weak interactions), whereas N-H...O interactions dominate the cocrystal (43.0 %). The resulting cocrystal exhibits markedly reduced moisture uptake and mechanical sensitivity (IS = 25 J, FS = 192 N), demonstrating that crown-ether complexation is an effective approach for stabilizing pentazolate-based energetic materials.

Despite substantial progress in nanothermometry typically operational at temperatures <= 573 K, fluorescencebased sensors for extremely high-temperature environments such as aviation engines, nuclear reactors, and industrial processes remain quite inadequate due to the severe suppression of luminescence under such harsh conditions. Herein, we present a back-energy-transfer (BET) switching approach applied to Yb/Tm-doped Y2O3 nanostructures to selectively achieve either high relative sensitivity (S-r) or an extended sensing range. When the BET channel is activated via uniform co-doping ("on" state), the fluorescence intensity ratio (FIR) between the three-photon (477 nm) and two-photon (810 nm) emissions exhibits exceptional S-r due to their dependencies on BET, yielding a maximum S-r of 3.93% K-1 at 873 K, nearly quadruple the typical S-r (similar to 1% K-1) of sensors operating at much lower temperatures. However, the activation of BET accelerates quenching of the three-photon emission, making it unable to operate at higher temperatures. In comparison, spatially isolating Yb3+ and Tm3+ ions through core-shell engineering significantly inhibits BET ("off" state), mitigating thermal quenching and maintaining detectable luminescence up to 1173 K. This work establishes a fundamentally versatile approach to designing high-temperature thermometers by strategically controlling BET pathways to meet tailored requirements for either high-sensitivity detection or wide-range monitoring.

Although near-infrared (NIR)-absorbing acceptors tend to capture more photons to boost the photocurrent (JSC) of polymer solar cells (PSCs), they often suffer from significant energy loss (Eloss), resulting in a low photovoltage (VOC), which limits further improvement of the power conversion efficiency (PCE). Herein, we developed four selenium-fused NIR-absorbing acceptors (Y-SeNF, Y-SeNF-2ClO, Y-SeBNF, and Y-SeBNF-2ClO) by regulating the molecular photoelectric properties via end-group and side-chain dual-engineering. Among them, Y-SeNF-2ClO with linear side-chains and asymmetric end-groups showed favorable molecular packing and energy levels, achieving an optimized active layer morphology and suppressed energy loss. Therefore, among the binary PSCs with a polymer donor D18, the Y-SeNF-2ClO device achieved the minimized Eloss and the highest product of VOC×JSC, leading to a champion PCE of 17.41

While fluorination and alkyl chain modifications are recognized as effective strategies for regulating the packing behavior of non-fullerene acceptor (NFA) molecules, their specific impacts on dielectric properties and associated energy losses in organic solar cells (OSCs) remain unclear, posing a constraint on further efficiency enhancements. To address this gap, it is designed and synthesized a series of NFAs with systematically varied quinoxaline fluorination degrees and alkyl chain lengths, aiming to elucidate the structure-property relationship whereby molecular architecture governs dielectric characteristics, directs molecular packing, and ultimately dictates device performance. This findings demonstrated that both increased core fluorination and extended alkyl side chains enhance the dielectric properties of NFAs while concurrently reducing the free volume within the molecular packing. Notably, the C12BQ-o8F molecule-featuring octa-fluorination and a 2-butyloctyl side chain-achieved the highest dielectric constant (2.42) and exhibited dense in-plane molecular packing (19.50 & Aring;), facilitating ultrafast hole transfer and markedly reducing voltage loss (0.491 eV). When incorporated as a guest acceptor into the PM6:BTP-eC9 binary host, the resulting ternary device attained an efficiency of 19.52%. This work elucidates the critical interplay between core fluorination and side-chain engineering in modulating dielectric properties, offering a molecular design pathway toward low-loss, high-efficiency OSCs.

Molybdenum oxide (MoOx), commonly adopted as an HTL material, offers potential for solution-based processing. Precise control over the oxidation state of molybdenum (Mo) within the HTL is crucial for achieving optimal OSC performance. In this study, we present an n-type doping strategy for MoOx by incorporating highly conductive Ti3C2Tx as an n-type dopant. The surface functional groups of Ti3C2Tx MXene mediate an auxiliary reduction process, selectively converting a fraction of Mo(VI) to Mo(V) and thereby yielding n-doped MoOx. Leveraging the intrinsic high electrical conductivity of Ti3C2Tx MXene, the resulting Ti3C2Tx-MoOx composite exhibits markedly enhanced conductivity relative to pristine MoOx, ultimately enabling the fabrication of high-performance OSCs with robust interfacial stability. Devices featuring the optimized Ti3C2Tx-MoOx composite HTL achieve a champion power conversion efficiency (PCE) of 17.44%, outperforming control devices based on PEDOT:PSS (16.36%) or pristine MoOx (16.48%). The versatility of this composite HTL is further demonstrated by its effectiveness in boosting the PCE of OSCs based on both PM6:Py-DT and PBDB-T:ITIC active layers. This work represents a step toward mitigating the longstanding conductivity-processability trade-off in inorganic HTLs, offering a promising material design strategy to support the development of high-performance and stable OSCs.

The ternary strategy is a promising approach to further boost the photovoltaic performance of organic solar cells (OSCs). However, designing and preparing a promising third component to effectively regulate the morphology of the ternary blends and achieve excellent power conversion efficiencies (PCEs) remains challenging. Commonly, promising third components (e.g., second acceptors) are typically either crystalline (with the risk of overaggregation) or amorphous (as passive diluents). Herein, we synthesized two amorphous wide-bandgap molecules, featuring a dithienocyclopentathieno[3,2-b]thiophene electron-donating core and 1,3-dimethylbarbituric acid (ITT-BA) and 1,3-diethyl-2-thiobarbituric acid (ITT-EB) as end groups, which act as thermodynamic crystallization promoters to adjust the evolution of the active layer in PM6:Y6-based OSCs. Interestingly, at optimal additions, these amorphous wide-bandgap small molecules combine strongly with Y6 to form alloy phases with increased melting enthalpy (Delta H m), indicating that the enhancement of the nucleation barrier transforms the film solidification of the ternary blend into a slow and controllable process. Therefore, ITT-BA and ITT-EB promote crystallization-guided phase separation, thus forming a highly ordered and oriented acceptor phase. The optimized ternary morphology slightly decreases the hole mobilities and improves the electron mobilities, achieving balanced charge transport and suppressing nonradiative losses, enabling the PM6:Y6:ITT-BA and PM6:Y6:ITT-EB ternary devices to achieve champion power conversion efficiencies (PCE) of 19.19% and 19.40%, with concurrent improvements in open-circuit voltage (V OC), fill factor (FF), and short-circuit current density (J SC), significantly surpassing the 18.41% PCE of the PM6:Y6 binary counterpart. The versatility of this thermodynamic modulation strategy has been demonstrated in other high-performance systems, highlighting the effectiveness of these amorphous wide-bandgap molecules in regulating the crystallization process of Y-type host acceptors to achieve high-efficiency OSCs.

Organic solar cells (OSCs) hold great promise for next-generation photovoltaics, yet achieving both high efficiency and long-term stability remains a formidable challenge. This difficulty originates from the multiple influences of crystallization kinetics and thermodynamics in bulk heterojunction films. Herein, we introduce a nematic liquid crystal, 3UTPP4, to synergistically regulate both the kinetic and thermodynamic aspects of film formation in the PM6:BTP-eC9 system. 3UTPP4 prolongs the film formation process, enabling more controlled molecular assembly and effectively circumventing the metastable state (cold crystallization) of BTP-eC9. The resulting films exhibit enhanced molecular ordering with reduced π-π stacking distance, suppressed recombination, and improved charge carrier mobility. Consequently, the optimized devices deliver a power conversion efficiency (PCE) of 20.07% with an excellent fill factor (FF) of 80.51%. Moreover, outstanding device stability was successfully realized, retaining 95% of the initial PCE after 1,600 h of storage in nitrogen and achieving a photothermal stability T80 exceeding 1,000 h. The generality of this strategy is further validated across other high-performance systems, with D18:L8-BO achieving an excellent PCE of 20.73% and an FF of 82.14%. This work establishes liquid crystal-assisted synergistic regulation of kinetic and thermodynamic processes as a promising pathway toward efficient and stable OSCs.

A novel photochromic azoporphyrin compound was designed and synthesized, featuring a covalent linkage through an amide bond. The compound, designated as 5,10,15-triphenyl-20-{4-[4-(2-(3,5-dimethyl-1H-pyrazol-4-yl))diazenyl]benzamido}phenylporphyrin (TPP-AAP), incorporates an azo-functional group that confers photochromic properties. Its molecular structure and photochromic properties were characterized using NMR spectroscopy, UV-vis spectroscopy, and fluorescence spectroscopy. Upon the addition of a weak base (Na2CO3), the azo unit of TPP-AAP underwent trans -> cis isomerization upon irradiation at 254 nm UV light; the reverse process (cis -> trans) could be induced by subsequent irradiation with 450 nm visible light. The compound maintained stable antifatigue performance after multiple cycles. Fluorescence spectral analysis revealed that upon UV irradiation, the intense Q(0,0) emission band at 652 nm was significantly quenched. Concurrently, the Q(0,1) band at 718 nm underwent a blue shift to 706 nm, accompanied by an increase in intensity. These results demonstrate that the molecular conformational change significantly modulates the excited-state relaxation pathway. Consequently, the corresponding fluorescence signal provides an effective mechanism for nondestructive readout.

Lithium pentazolate (LiN5) is a novel nitrogen-rich energetic material that exhibits excellent detonation properties. However, it is difficult to control its crystal morphology after precipitating from a single solvent. Herein, various crystal morphologies were obtained by adjusting the solvents (NMP, DMA, DMF, and EtOH) and antisolvents (DCM, EA) combination. In contrast to the raw material with a cubic morphology, the LiN5 crystals derived from DMA-EA adopt a rod-like morphology, while the EtOH-EA and EtOH-DCM yield tetragonal block-like and quasi-ellipsoidal morphologies, respectively. Both cubic and tetragonal block-like crystals show higher thermal stability (159 degrees C-161 degrees C) than that of rod-like and quasi-ellipsoidal counterparts (148 degrees C-150 degrees C). The impact sensitivity (IS) of quasi-ellipsoidal crystals (IS = 25 J) is superior to that of rod-like (IS = 8 J) and tetragonal block-like (IS = 15 J) morphology. Unfortunately, the desired quasi-ellipsoidal crystals exhibit slightly higher hygroscopicity with a water content of 7.8% under the same conditions. Moreover, XRD analysis shows that the EtOH solvent leads to a significantly enhanced diffraction peak corresponding to the (430) plane of LiN5, whereas the EA antisolvent results in an additional distinct peak assigned to the (432) plane. Our results propose a general strategy for regulating the crystal morphology of LiN5, further revealing the connection between crystal morphology and physical-chemical properties.

Rapid progress has been achieved in organic solar cells (OSCs) since the emergence of Y6 and its derivatives. However, the open-circuit voltages (V OC) of efficient OSCs remain relatively low, which poses a potential obstacle to further performance improvements. Another drawback is the over aggregation of Y-type molecules in the active layer, leading to an unbalanced charge transportation. To address these issues, two wide-bandgap dimeric acceptors, BETh4O and BETh4S, were synthesized and used as second acceptors in the PM6:BTP-eC9-based binary device. Benefiting from their up-shifted LUMO energy levels and wide bandgaps, these two dimers constructed cascade energy levels and complementary absorption with PM6 and BTP-eC9. In addition, the two dimers exhibit distinct cold crystallization temperature (T CC) and melting characteristics, which are beneficial to use to adjust the crystallization characteristics of BTP-eC9. Unlike BETh4S with a 1,3-diethyl-2-thiobarbituric acid end group, BETh4O sealed by 1,3-dimethylbarbituric acid is characterized by a higher melting point and a lower melting enthalpy, indicating stronger intrinsic crystallinity and structural order. This inherent order enables BETh4O to serve as an effective template for guiding the crystallization of host acceptor BTP-eC9 into highly ordered domains. Consequently, the resulting PM6:BTP-eC9:BETh4O ternary OSCs demonstrate enhanced and balanced charge transport, suppressed bimolecular and trap-assisted recombination, and improved charge collection. These advantages collectively contribute to simultaneous increases in V OC and fill factor (FF) without sacrificing the short-circuit current density (J SC), yielding a power conversion efficiency (PCE) of 19.00%, which surpasses that of the binary PM6:BTP-eC9 device (18.40%) and the PM6:BTP-eC9:BETh4S ternary device (18.45%). This work demonstrates the efficacy of wide-band gap dimers in controlling active-layer crystallinity for high-efficiency OSCs.

Highly emissive two-dimensional imine-linked covalent organic frameworks (COFs) remain challenging to construct, as strong interlayer π-π stacking and intramolecular rotation typically induce severe nonradiative decay and fluorescence quenching. Herein, three isostructural pyrene-based COFs had been synthesized, and the hydroxy-functionalized one (OH-COF) exhibited the strongest solid-state photoluminescence with a PLQY of 12.15%. The results revealed that the superior fluorescence of OH-COF originated from the synergistic effects of electronic modulation by the hydroxyl groups and structural locking via hydrogen bonding with imine moieties, which effectively suppress nonradiative transitions from the imine nitrogen lone pairs and thereby enhance the emission. Furthermore, OH-COF, equipped with distinctive dual N,O chelation binding sites, not only delivered outstanding selectivity for metal ions but also enabled a low detection limit of 0.14 μM for Fe3+ and a fast response time. This work provides valuable insights for the design of emissive imine COFs, offering a promising strategy for the development of high-performance luminescent sensors.

ABSTRACT Flexible organic scintillators are attractive for conformal x‐ray imaging but are fundamentally limited by a thickness–transparency–resolution trade‐off, as the film thickness required for efficient x‐ray absorption generally increases light scattering from dispersed phosphor domains. Here, we overcome this limitation by introducing molecular miscibility as a design principle for single‐phase organic scintillators. A water‐soluble carbazole–quaternary phosphonium copolymer is co‐processed with poly(vinyl alcohol) to form a fully amorphous film in which the emitter is molecularly integrated within the polymer network. This architecture suppresses refractive‐index scattering while rigidifying the phosphorescent chromophores, simultaneously enabling high optical transparency and efficient room‐temperature phosphorescence. The optimized scintillator exhibits 88.1% transmittance at 300 µm thickness, a light yield of 16 533 photons MeV − 1 , and a spatial resolution of 12 lp mm − 1 , while supporting large‐area fabrication, multicolor scintillation through molecular co‐doping, and conformal x‐ray imaging of curved objects with reduced geometric distortion. This work establishes molecular miscibility as a general strategy for minimizing morphology‐induced optical losses, providing a pathway toward flexible scintillators that combine efficient x‐ray stopping with high‐resolution imaging.

Nonfullerene acceptors have emerged as core materials for near-infrared (NIR) organic photodetectors (OPDs), driving performance breakthroughs owing to their tunable molecular structures and excellent NIR light-harvesting capabilities. However, current high-performance NIR OPDs face several critical challenges, such as limited material diversity, restricted long-wavelength response range, and insufficient dark current suppression, which severely hinder their practical applications. In this study, two fused-ring quinoxaline-modified Y-type nonfullerene acceptors, BF-4F and NF-4F, with phenanthrene-fused quinoxaline and phenanthroline-fused quinoxaline structures, respectively, were designed and synthesized. Owing to the enhanced electron-withdrawing property of phenanthroline, NF-4F exhibited deeper molecular energy levels and a slightly wider band gap. Bulk heterojunction OPD devices were fabricated by blending the two materials with PM6. The results showed that the OPD device of BF-4F exhibits significantly superior comprehensive performance compared to the NF-4F-based device, demonstrating an efficient photoresponse in the NIR region (700-1000 nm) with a high specific detectivity of 1.78 & times; 1013 Jones at 850 nm. Under zero bias, the BF-4F-based device exhibits rise time/fall time (tau r/tau f) values of 505.1/250.7 ns, which are markedly faster than those of the NF-4F-based counterpart (2.31/2.76 mu s). The excellent performance of the BF-4F-based OPD is mainly attributed to its outstanding charge-transport capability, arising from the improved morphology and crystallinity of the blend film, which significantly enhances carrier mobility and promotes exciton dissociation and transport. This study demonstrates the profound impact of the structural and electronic properties of fused-ring quinoxalines on the photodetection performance of Y-type acceptors, highlighting the effectiveness of the fused-ring quinoxaline modification strategy and offering a promising molecular design strategy for achieving NIR materials for high-performance OPDs.

Near‐infrared (NIR) organic light‐emitting diodes (OLEDs) based on acceptor‐donor‐acceptor (A‐D‐A)‐type molecules are attractive for applications in biological imaging, optical communication, and night vision. However, their performance is often limited by low radiative efficiency arising from unfavorable exciton recombination zones and poor light outcoupling. Here, we demonstrate high‐performance NIR OLEDs by incorporating a one‐dimensional Bragg grating into a thermally cross‐linkable hole‐transporting layer (PF8Cz‐X) via microtransfer molding. This interlayer introduces hole traps that confine the exciton recombination zone to the vicinity of the anode, substantially enhancing the Purcell factor and boosting the effective radiative quantum efficiency. Simultaneously, the imprinted grating modifies the optical mode distribution, scattering surface plasmon polariton modes into extractable light. The optimized devices exhibit an emission peak at 880 nm, a maximum external quantum efficiency of 1.55%, and a peak radiant exitance of 74.67 mW cm−2, representing one of the highest‐performing solution‐processed NIR OLEDs beyond 800 nm. This work establishes a synergistic electrical and optical engineering strategy to overcome efficiency limitations in NIR OLEDs.

Although near-infrared (NIR)-absorbing acceptors tend to capture more photons to boost the photocurrent (J SC) of polymer solar cells (PSCs), they often suffer from significant energy loss (E loss), resulting in a low photovoltage (V OC), which limits further improvement of the power conversion efficiency (PCE). Herein, we developed four selenium-fused NIR-absorbing acceptors (Y-SeNF, Y-SeNF-2ClO, Y-SeBNF, and Y-SeBNF-2ClO) by regulating the molecular photoelectric properties via end-group and side-chain dual-engineering. Among them, Y-SeNF-2ClO with linear side-chains and asymmetric end-groups showed favorable molecular packing and energy levels, achieving an optimized active layer morphology and suppressed energy loss. Therefore, among the binary PSCs with a polymer donor D18, the Y-SeNF-2ClO device achieved the minimized E loss and the highest product of V OC & times;J SC, leading to a champion PCE of 17.41%, outperforming other devices based on acceptors with branched side-chains and/or symmetric end-groups. Encouraged by the above success, NIR-absorbing Y-SeNF-2ClO was also introduced into the classic D18:L8-BO host system to fabricate efficient ternary PSCs. Notably, the D18:L8-BO:Y-SeNF-2ClO device offered a further improved PCE of 20.08%, ranking among the highest values reported for asymmetric acceptors. This work provides a feasible molecular design strategy for end-group and side-chain dual-engineering to develop NIR-absorbing acceptors for constructing efficient PSCs.

Interface engineering is widely recognized as a key strategy for boosting both the performance and longevity of devices, thereby significantly contributing to the feasibility and success of organic solar cells (OSCs) in the market. In this work, we present a facile aqueous-based fabrication scheme for the introduction of an ultrathin MoO3 buffer layer, which exhibits excellent ion-blocking capability between indium-tin oxide and poly(3,4-ethylenedioxythiohene):poly(styrenesulfonate) (PEDOT:PSS) in conventional OSCs. The MoO3 buffer layer is deposited onto the substrate via spin-coating, utilizing a colloidal dispersion of MoO3 nanoparticles (NPs) synthesized through a low-temperature hydrothermal method. The MoO3 buffer layer not only effectively inhibits the corrosive effects associated with PEDOT:PSS but also improves energy-level matching at the hole-transport layer (HTL)/active layer interface, thereby enhancing the process of hole extraction. Accordingly, OSCs incorporating the MoO3/PEDOT:PSS structure attain a power conversion efficiency (PCE) of 18.67%, exhibiting a notable improvement over the control OSCs (PCE = 17.58%) based on the PEDOT:PSS HTL. Remarkably, unencapsulated devices maintain 82% of the initial efficiency following 750 h of storage in a glovebox, representing good stability for potential practical applications.

Low mechanical sensitivity is an evaluation index for the development of safe and stable high-energy materials. Herein, 3,6-Dinitropyrazolo[4,3-c]pyrazole (DNPP) and its ionic salts 1 - 4 with a fused-ring backbone were synthesized...

The persistent challenge of organic pollutant remediation drives the development of sulfate radical-based advanced oxidation processes, where heterogeneous cobalt-based catalysts face critical stability limitations. To address this, we rationally designed kaolinite-supported carbon-coated cobalt composites through calcination of ZIF-67/Kaol precursors, achieving enhanced peroxymonosulfate (PMS) activation for atrazine degradation. The engineered catalyst combines lamellar structure and active surface groups of kaolinite with ZIF-67-derived nitrogen-doped carbon frameworks, exhibiting exceptional catalytic performance. Mechanistic studies reveal singlet oxygen as the exclusive reactive species, with nitrogen doping in the carbon matrix substantially enhancing charge density and electron transfer efficiency. The carbon coating facilitates electron redistribution while protecting active cobalt sites, enabling sustained catalytic cycles. This work establishes a materials design paradigm combining mineral support engineering with metal-organic framework derivation strategies, demonstrating significant potential for developing robust PMS activation systems in water remediation applications.

Three new water-soluble photoswitches (PH, PM, and PB) were synthesized via assembling N-methylpyridinium to 3-pyridylazoindole scaffold which we previously researched. The n-pi* absorption of the 3-pyridylazoindolium exhibited a significant red-shift compared to their unmodified state, which meant the N-methyl photoswitches might achieve photoisomerization upon the irradiation of visible light. In both organic and aqueous solvents, the photoswitches PB exhibited excellent reversible photoswitching and regular thermal stability. In addition, the n pi* transition of compound PB red shifted 20 nm compared to its unmodified state (3). Under simulated biological conditions, the presence of glutathione (GSH) not only almost without impact on the photoisomerism of PB in aqueous solution, but also did not affect the optical fatigue resistance. Besides, because of the N-methylpyridinium of the scaffold compound PB, the adhesion of molecule and hydroxide ions was significantly enhanced and achieved discoloration towards acid-alkali. These results indicated that modification of N-methyl not only is an excellent strategy for enhancing the application potential of 3-pyridylazoindole photoswitches in aqueous phase, but also achieving detection of alkaline strength by 3-pyridylazoindole scaffold in aqueous solution.