Wide-bandgap perovskite solar cells have shown great potential in tandem photovoltaic applications; however, insufficient interfacial charge transport remains a key bottleneck limiting further efficiency improvements. In this work, NiOx hole transport layers with different thicknesses were prepared by tuning the precursor concentration, and their effects on interfacial properties and device performance were systematically investigated. The results show that increasing NiOx thickness leads to a higher work function and improved surface wettability, which facilitates more uniform spreading and nucleation of the perovskite precursor, resulting in smoother perovskite films with larger grain sizes. Steady-state photoluminescence measurements indicate that the film prepared at an intermediate concentration exhibits the most efficient interfacial charge extraction. Consequently, the device performance shows a pronounced thickness dependence, with the 5 mg mL-1 device achieving the best power conversion efficiency (PCE) of 19.41%. These results demonstrate that simple thickness modulation enables synergistic optimization of NiOx interfacial properties, providing an effective strategy for interface engineering in wide-bandgap perovskite solar cells.
Achieving efficient and narrowband deep-blue emission remains a persistent challenge for multiple-resonance thermally activated delayed fluorescence (MR-TADF) materials, which are essential for high-definition organic light-emitting diode (OLED) displays. Here, we present a synergistic backbone-donor engineering strategy that transforms a simple mono-boron B/N/O framework into an efficient deep-blue emitter with high spectral sharpness. By synergistically integrating an auxiliary donor, 10-phenyl 5H-phenophosphazinine 10-sulfide (NPS) and rigid carbazole-fused motif within the MR backbone, this synergistic modification simultaneously accelerates reverse intersystem crossing and suppresses specific medium-to-high frequency molecular vibrations that contribute to spectral broadening by steric hindrance traction effects, enabling efficient triplet harvesting and significant narrowband emission. The suppressed molecular vibrations yield a small full-width-at-half-maximum (FWHM) of only 18 nm at 444 nm in toluene. The OLEDs based on proof-of-concept achieve an external quantum efficiency (EQE) of 32.9% with deep-blue CIEy coordinate of 0.067, retaining high efficiencies of 25.1% and 16.6% at 100 and 1000 cd m- 2, respectively. This work represents a significant step toward addressing the longstanding trade-off between efficiency and color purity in deep-blue MR-TADF systems, offering a versatile molecular design principle for next-generation display and lighting technologies.
Organic semiconductor lasers (OSLs) remain challenging due to triplet-induced optical losses, such as singlet-triplet annihilation and triplet excited-state absorption, which become prominent at high exciton densities and increase the lasing threshold. In this study, we investigate a novel bifunctional molecule, BOXDP3, which incorporates an anthracene dimer unit into a benzobisoxazole derivative with a low amplified spontaneous emission (ASE) threshold. BOXDP3 exhibits a low ASE threshold of 3.8 mu J cm-2 in a 2 wt% CBP-doped film, representing a significant reduction compared to previously reported anthracene derivatives. Furthermore, through concentration-dependent triplet-triplet upconversion (TTU) threshold analysis in triplet-sensitized solutions, we provide evidence of intramolecular TTU activity in BOXDP3. In 0.5 wt% doped CBP thin films, longlived delayed fluorescence exceeding 100 mu s is observed, originating from triplet-to-singlet recycling via intramolecular TTU. These results indicate that incorporating intramolecular TTU functionality into laser materials would be an effective strategy for realizing next-generation, low-threshold, and stable organic semiconductor lasers.
We compare organic light-emitting diode (OLED) performance in devices based on MQAB emitters doped into similar electron transporting molecular hosts, TBADN (2-tert-butyl-9,10-di(naphtha-2-yl) anthracene) and PADN (2-phenyl-9,10-di(naphtha-2-yl) anthracene), the former exhibiting spontaneous polarization due to molecular orientation (SOP) while the latter does not. We quantify the host electric polarization and find that the device efficiency is lower when using the more polarized TBADN. Using charge modulation spectroscopy, we infer the root cause to be quenching of the luminescent excited state by cations that accumulate in the hole transport layer at the emissive interface. The cation accumulation is caused by interfacial charges associated with the SOP and persists even under conditions where the OLED emits light.
Organic solar cells (OSCs) have attracted significant research interest as next-generation photovoltaic technologies due to their environmental friendliness, lightweight nature, and flexibility. However, the performance of OSCs exhibits notable sensitivity to variations in incident light angle, which restricts their practical application under real-world illumination conditions to some extent. In this paper, a microstructure film composed of polystyrene (PS) and poly (methyl methacrylate) (PMMA) was fabricated on the back side of the device via a straightforward spin-coating process to reduce angular dependence of OSCs' efficiency on incident light. At an optimal blending ratio of 3:7, a trench-like microstructure forms, enhancing internal light reflection and extending the optical path length. Consequently, the short-circuit current density increases from 25.54 mA/cm2 to 26.47 mA/cm2, and the power conversion efficiency improves from 14.08% to 14.77% under normal incidence. More importantly, the device retains 94.1% of its initial efficiency at an oblique incident angle of 45 degrees, demonstrating excellent angular independence. This research presents a promising approach for reducing the angular dependence of OSCs' performance on incident light, which is expected to facilitate their wider adoption in practical industrial applications.
The performance of organic electronic devices is closely tied to their nanoscale donor-acceptor microstructure, yet quantifying these features remains challenging using conventional characterization tools. X-ray scattering and electron microscopy techniques provide high-fidelity structural information, but they are slow, expensive, and challenging to deploy in high-throughput or autonomous processing environments. Here, we propose a complementary, proxy-based route to microstructure inference that leverages the device's transient short-circuit current response under modulated illumination. Using a microstructure-aware excitonic drift-diffusion (EDD) framework that incorporates arbitrary time-dependent generation profiles, we compute current (J(t)) responses for 500 computationally generated donor-acceptor morphologies subjected to full-wave-rectified sinusoidal excitation. From each response, we extract a suite of physically motivated time-and frequency-domain features and pair them with key microstructural descriptors, specifically interfacial area, characteristic domain size, and connectivity. SHAP-based feature selection reveals that a compact subset of transient-response features captures most of the microstructure dependence. Linear surrogate models trained on these subsets achieve good test R2 across all descriptors, with interfacial area and domain-size predictions exceeding R2 = 0.9, using fewer than 10% of the simulated morphologies for training. These results demonstrate that high-frequency, amplitude-modulated electrical measurements can recover essential microstructural fingerprints, suggesting a pathway toward compact, non-destructive, and automation-ready characterization tools for high-throughput research in organic electronics.
This study presents an antisolvent-free, one-step spin-coating method for fabricating {CH(NH 2 ) 2 } 1-x Cs x PbI 3 (FA 1x Cs x PbI 3 ) perovskite films using a volatility-controlled cosolvent. Using 2-Methoxyethanol (2-ME) as a highly volatile primary solvent to drive rapid supersaturation, while 1-cyclohexyl-2-pyrrolidone (CHP) acts as a highboiling-point cosolvent to moderate crystallization kinetics through intermediate stabilization. Crucially, CsCl is introduced as a strategic additive to overcome the inherent low solubility of conventional cesium precursors in 2-ME. CsCl appears to play dual roles: enabling effective Cs + incorporation to stabilize the alpha-phase perovskite and likely assisting crystallization by facilitating the formation of transient chloride-mediated intermediates. Optimizing the formulation with 3.5 vol% CHP and 7.5 mol% CsCl led to significant improvements in film uniformity, crystallinity, and optical properties. Consequently, n-i-p planar heterojunction solar cells fabricated using a 0.45 M precursor solution achieved a high power conversion efficiency of 21.1% with short-circuit current density (25.8 mA/cm 2 ), open-circuit voltage (1.06 V), and fill factor (77.5%), and a stabilized output of 20.8%, confirming the potential of this DMF- and antisolvent-free process for scalable PSC production, while emphasizing that the present approach is based on volatility control rather than complete solvent detoxification.
Near-infrared (NIR) absorbing and/or emitting organic materials are increasingly important for next-generation optoelectronic devices. Narrow-gap push-pull conjugated polymers have gained particular attention in this respect because of their tunable optical properties and promising performance in (semitransparent) organic photovoltaics and NIR photodetectors. In this study, three novel diketopyrrolopyrrole (DPP) based narrow-gap donor polymers containing fluorine-, chlorine-, or nitrile-substituted thiophene units are rationally designed and synthesized with the aim of enhancing the open-circuit voltage in NIR-active (semitransparent) organic solar cells. The P-DPP-3T(F):Y6 blend affords a power conversion efficiency of 5.2%, surpassing the P-DPP-3T:Y6 reference combination (yielding 4.5%). Further optimization with other NIR-absorbing non-fullerene acceptors gives an enhanced solar cell efficiency of 6.6% for the P-DPP-3T(F):Y16F combination, and even 7.8% for P-DPP-3T:Y16F. When utilized with a semitransparent top electrode, the latter affords an efficiency of 5.0% with an average visible transmittance of 33%.
In this study, poly(furfuryl alcohol) (PFA) was chemically modified by Diels-Alder addition of maleic anhydride (MA; 1, 2, 3, 5, and 15 phr) to increase carbonyl functionality and enable ambient-temperature curing with an amine hardener. Modified PFA (mPFA) samples were cured with a polyamine (HY) and, because carbonyl content alone was insufficient to achieve satisfactory mechanical performance, blended with a commercial epoxy (Araldite LY 5052) at varying weight ratios (10-50 phr). The modification reaction and curing kinetics were followed by FTIR and chemorheology; chemical structure was confirmed by H-1/(CNMR)-C-13. Hardness, tensile (ASTM D638 type V), DMTA and TGA characterized the cured networks. FTIR and rheology showed that 1-3 phr MA produces effective modification and that 30 phr HY is sufficient for ambient curing. Incorporation of 50 phr epoxy substantially improved mechanical and thermal performance: PFA-50 exhibited hardness 253 +/- 2 cycles, tensile strength 7.58 +/- 0.38 MPa, Young's modulus 71.01 +/- 1.19 MPa and Tg 57.48 degrees C, while the best-performing MA-modified formulation (PFA/2MA-50) reached hardness 309 +/- 2 cycles, tensile strength 10.19 +/- 0.54 MPa, Young's modulus 126.9 +/- 2.22 MPa and T-g 66.94 degrees C. TGA showed increased char yield for PFA/2MA-50 (15.7 wt.% at 800 degrees C) versus epoxy alone (9.7 wt.%). DFT calculations (B3LYP/6-31G (d,p), implicit DMF) support amide formation as a favorable curing pathway for MA-modified segments and are consistent with ATR-FTIR assignments. The combined MA modification and epoxy integration yields ambient-curing, mechanically robust PFA-based networks with improved thermal stability, making them promising binders for intumescent coatings.
A series of s-triazine-based homopolyesters was synthesized via polycondensation of a 4,6-bis-(N-(4-(benzoylchloride)amino))-2-(N-benzyl-piperazin-1-yl)-1,3,5-triazine (monomer) with various aliphatic and aromatic diols. The structures were confirmed using FT-IR and 1H NMR spectroscopy. Physicochemical characterization revealed that polyesters containing aromatic moieties exhibited higher density, intrinsic viscosity, and improved thermal stability compared to those derived from aliphatic diols. Solubility studies indicated enhanced dissolution behaviour in polar aprotic solvents at elevated temperatures. Thermogravimetric analysis demonstrated significant thermal resistance, particularly for bisphenol-based systems. The thermal degradation kinetics were evaluated using Coats-Redfern, Horowitz-Metzger, Broido, and Chan methods, showing consistent trends with variations attributed to model assumptions. The overall degradation trends remained consistent. The combined physicochemical and thermal characteristics suggest that these s-triazine-based homopolyesters may be promising candidates for advanced materials requiring thermal resistance and structural stability.
The rapid advancement of aerospace and wind power industries necessitates epoxy resin matrices with simultaneous high strength and high toughness. However, conventional modification methods struggle to mitigate the trade-off between strength and toughness in epoxy resins, rendering the development of epoxy resins with both high strength and high toughness a persistent challenge. In this study, two Xylok epoxy resins (X-PPEP and X-BPEP) were synthesized utilizing para-xylene dimethyl ester (PXDM) and 4,4 '-bis(methoxymethyl)biphenyl (BMMB) as raw materials, respectively. Subsequently, with 4,4 '-diaminodiphenylmethane (DDM) serving as the curing agent, the properties of the corresponding castings and composites were investigated. The results reveal that the crosslinked networks of X-PPEP/DDM and X-BPEP/DDM exhibit highly rigid backbones and substantial free volume fraction, thereby endowing them with exceptional mechanical properties. Specifically, the tensile strength and elongation at break of both systems exceeded 90 MPa and 7%. The impact strength of X-BPEP/DDM reached 49.72 kJ/m(2). Furthermore, the glass fiber-reinforced composites based on these resins also exhibited excellent mechanical properties. These findings provide a viable strategy for fabricating epoxy resins with balanced strength and toughness, highlighting the significant application potential of X-PPEP and X-BPEP in high-performance sectors such as aerospace and wind power generation.
A new diether-diamine monomer, 1,1-bis [4-(4-aminophenoxy)-3-methylphenyl]cyclopentane (BAMPC), containing a cardo cyclopentane unit and a pendant methyl substituent, was synthesized through a multistep procedure. The structure of the methyl-substituted diether-diamine monomer was confirmed using FT-IR, 1H NMR, 13C NMR, and mass spectrometry. Polycondensation of BAMPC with aromatic dialdehydes, including terephthalaldehyde and isophthalaldehyde, produced a series of co-poly (azomethine-ether)s incorporating cardo cyclopentane units in the polymer backbone. The influence of the cardo cyclopentane structure and pendant methyl group on the solubility and thermal stability of the resulting co-poly (azomethine-ether)s was examined. The polymers exhibited glass transition temperatures (Tg) in the range of 165-178 degrees C and thermal degradation temperatures (Td) between 456 and 486 degrees C, indicating thermal stability. The polyazomethines were soluble in polar aprotic solvents such as DMF, NMP, DMAc, and DMSO at ambient temperature or upon heating. X-ray diffraction analysis indicated that SPAM-2, SPAM-3, SPAM-4, and SPAM-5 exhibited amorphous characteristics with a broad diffraction peak around 2 theta approximate to 20 degrees, whereas SPAM-1 showed semicrystalline behaviour. The inherent viscosities of the co-poly (azomethine-ether)s ranged from 0.20 to 0.39 dL g-1.
Quantum dot (QD) inks incorporating scattering particles offer great potential for high-performance color conversion layers with high color purity and wide color gamut. Electrohydrodynamic (EHD) printing enables high-resolution additive manufacturing but is limited by the lack of suitable scattering inks. Here, we systematically optimized a QD ink system by mixing TiO2 scattering particles for color conversion applications. The dispersion stability and continuous inkjet behavior of TiO2 particles were investigated, revealing that low-boiling-point solvents lead to rapid evaporation and nozzle clogging. Isobornyl methacrylate (IBOMA) with high boiling point was therefore selected as the solvent. Optical characterization shows that the ink containing 4 wt% TiO2 achieves a blue-light absorption of 84.3% and a color conversion efficiency (CCE) of 11.4%, approximately 40% higher than that of pure QD ink, without noticeable aggregation over three days period. For the first time, EHD printing was successfully used to fabricate scattering-particle-doped QD color conversion patterns with pixel sizes of similar to 30 mu m, demonstrating the feasibility of scattering inks for high-resolution micro-LED color conversion.
Organic semiconductor nanoparticles-based electronic devices have sparked considerable interest as their manufacturing process allows the use of non-toxic solvents. However, the development of microfabrication techniques to pattern semiconductor nanoparticle film with benign solvent fell behind. Here, we demonstrate a simple and low-cost microfabrication process, where the patterning is done by solution-stamping of alcohol-soluble polymer and subsequent lift-off of semiconductor nanoparticles. To demonstrate the potential of the developed process, aligned solution-stamping was used to pattern different function layers of nanoparticle-based organic thin film transistors.
Pyrene has emerged as a key scaffold in the design of organic semiconductors, distinguished by its inherent propensity for aggregation, ease of functionalization, and capacity for robust pi-stacking interactions. However, the exploration and application of pyrene-based scaffolds in n-type semiconductors remain relatively scarce. To address this challenge, three novel pyrene-derived semiconductors functionalized with pentafluorophenyl (5 F) end-groups were synthesized and characterized in organic field-effect transistors (OFETs). Compared to the pyrene-core analogue (1,6-5FPy), the 4,9-diazapyrene (PyNN) -core derivatives (1,6-5FPyNN and 3,8-5FPyNN) exhibit deeper lowest unoccupied molecular orbital (LUMO) energy levels and enhanced electron transport properties, attributed to the incorporation of two nitrogen atoms into the pyrene framework. Through this synergistic modulation by N atoms doping and substitution site isomerism, the three molecules exhibit distinct conformation and packing motifs in the single crystals. Specifically, 1,6-5FPyNN possesses a reduced intramolecular torsion angle and strengthened intermolecular interactions, evidenced by short C-H & centerdot;& centerdot;& centerdot;N contacts (2.47 & Aring;). The molecules adopt an edge-on orientation on the substrate surface, and the polycrystalline films display elongated, interconnected grains (similar to 2 mu m), which is favourable for charge transport. The n-type small-molecule semiconductor 1,6-5FPyNN demonstrates optimal performance, achieving an electron mobility of 1.64 +/- 0.29 cm(2) V-1 s(-1), establishing this material as one of the most promising n-type small-molecule pyrene derivatives reported thus far.
Phthalonitrile (PN) resins exhibit outstanding thermal and mechanical properties but suffer from intrinsically high melting temperatures and sluggish curing kinetics, which severely restrict their processability and manufacturability. In this work, a eutectic blending strategy based on ternary PN monomers was employed to markedly depress the melting temperature, enabling mild and controllable melt prepolymerization with a diamine curing agent. This approach produced a low-melting phthalonitrile prepolymer (MPPh) exhibiting a viscosity below 1 Pa & centerdot;s at 88 degrees C, providing a stable melt-processing window. DSC and FTIR analyses revealed that the prepolymerization predominantly proceeded through linear chain growth via amino-nitrile addition reactions. To address the inherently low curing reactivity of MPPh, 3-aminophenylacetylene (APA) was introduced as a reactive diluent to activate the curing process and further tailor the rheological behavior. The modified resin (MP-m) demonstrated significantly enhanced curing efficiency and a reduced viscosity below 1 Pa & centerdot;s at 66 degrees C, excellent isothermal stability, and pronounced shear-thinning behavior. The cured MP-m resin retained excellent thermal stability and mechanical performance. These findings provide a simple and solvent-free strategy for the preparation of low-melting-point phthalonitrile, broadening the practical application potential of PN resins in high-temperature composite manufacturing.
In this study, a novel flame retardant designated as SFD, which contains phosphorus (P), nitrogen (N), and sulfur (S), was successfully synthesized via a one-pot method utilizing 2-aminobenzothiazole, furfural, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) as raw materials. This flame retardant was subsequently incorporated as an additive into epoxy resin (EP), with various formulations prepared using dicyandiamide (DDM) as the curing agent. The epoxy formulations containing only 3 wt% of SFD exhibited an improved Limiting Oxygen Index (LOI) of 34% and achieved UL-94 V-0 ratings. The Peak Heat Release Rate (PHRR), Total Heat Release (THR), and Total Smoke Production (TSP) for the EP/SFD composites were reduced by 28.0%, 30.1%, and 30.0%, respectively, in comparison to pure EP. Mechanical property assessments of the SFD/EP composites indicated that the incorporation of SFD had minimal impact on the mechanical properties of EP; thus, SFD can enhance the flame retardancy of EP without compromising its mechanical integrity. Analysis of the flame retardant mechanism revealed a significant P-N synergistic effect between the benzothiazole moiety and the phosphorus heterophenanthrene moiety present in SFD. The addition of SFD effectively mitigates heat release and smoke production during combustion processes involving EP while demonstrating excellent flame-retardant characteristics along with smoke suppression capabilities; furthermore, it promotes carbon layer formation. This research presents a straightforward strategy for synthesizing a multi-element synergistic flame retardant system that holds promise for application across a broad spectrum of thermoset plastics.
The permanently crosslinked networks of conventional thermosetting epoxy resins endow glass fiber-reinforced polymer (GFRP) composites with excellent mechanical performance and enable their widespread application in aerospace, automotive, and other fields, but make efficient recycling extremely challenging. In this study, dynamic boronate ester (B-O-C) bonds were introduced as reversible crosslinking units to replace traditional irreversible covalent linkages, enabling the construction of recyclable thermosetting epoxy materials. A concise and effective strategy was developed to construct reversible boronate ester networks within epoxy resins. A hydroxyl-rich linear prepolymer was prepared via aniline-initiated chain extension of bisphenol A-based epoxy resin and was crosslinked with tripropyl borate under catalyst-free conditions, yielding a recyclable epoxy vitrimer (EAT) with high mechanical performance and room-temperature degradability. Owing to the rapid alcoholysis kinetics of B-O-C bonds, the cured EAT thermosets and their GFRP composites could be completely depolymerized in pure methanol within 2 h, enabling clean separation and recovery of the resin and glass fibers. XPS analysis suggested that excess boron-containing groups may react in situ with silanol groups on the glass fiber surface, likely giving rise to Si-O-B interfacial linkages, which may contribute to the excellent mechanical properties of the composites. Reprocessed materials fabricated from recovered resin and fibers retained more than 80% of their original mechanical performance after one recycling cycle. This work provides an efficient and feasible route for achieving closed-loop chemical recycling of high-performance GFRP under mild conditions.
The inherent brittleness of epoxy (EP) has long imposed limitations on its utilization within advanced field. This study synthesized a novel high-performance soluble polymer with a tetramethyl biphenyl structure (named tetramethyl biphenyl poly arylene ether ketone, S-TBPAEK) as a toughening agent for preparing EP composites. The aromatic structure in S-TBPAEK enhanced the heat resistance of composites, while its unique tetramethyl structure promoted excellent compatibility with EP. Additionally, it was observed that when S-TBPAEK content reached 12.5 phr, the impact strength of composite was significantly increased by 170 %. Additionally, the mechanical properties of the composite, such as flexural strength and tensile strength, have been enhanced by approximately 43.7 % and 55.8 % respectively. Finally, the fracture surfaces of the composites were analyzed using SEM to investigate the fracture mechanism. The results revealed that the fracture behavior of impact, flexural and tensile specimens transitioned from brittle to ductile fracture. The phenomenon suggested that the S-TBPAEK/EP composite absorbed more energy during fracturing process, thereby enhancing its toughness. In summary, S-TBPAEK shows great promise as a toughening agent for epoxy composites, offering new insights into the field of epoxy toughening.
This study establishes a systematic mechanistic framework for phthalonitrile resins containing polyimide skeletons (PIPN) to address their narrow processing window and unclear thermo-mechanical regulation. Six PIPN model compound with varied dianhydride structures PM (PMDA), BP(BPDA), F (6FDA), ABP(ABPDA), K(BTDA), E (BPADA) were designed and synthesized. Through integrated multiscale simulations and experimental characterization, a comprehensive "structure-weak interactions-packing order-molecular mobility-energetics-macroscopic properties" correlation model was constructed for the first time. Molecular backbone rigidity, symmetry and planarity govern the performance: fully rigid PM-PIPN exhibited strongest pi-pi stacking and electrostatic interactions, yielding the highest melting point (390 degrees C) and superior predicted modulus. Conversely, flexible segments (E-PIPN) or sterically hindered groups (F-PIPN) systematically weakened intermolecular interactions, reducing both melting point and modulus while increasing Poisson's ratio. Electrostatic potential analysis, weak interaction visualization (IRI), mean square displacement (MSD) and cohesive energy density calculations synergistically revealed the regulation mechanisms from electronic, spatial, dynamic and energetic perspectives. This mechanistic framework provides theoretical foundations for rational molecular design of high-performance PIPN resins.
