Boosting performance of triboelectric nanogenerator via mechanical field-effect modulation

Structural modulation of D-D-π-A type metal-free organic sensitizers for high-performance dye-sensitized solar cells: The influence of alkyl and alkoxy chains.

Molecular engineering of phenoxazine-based sensitizers: DFT/TDDFT study of the effects of auxiliary acceptors on improving the efficiency of DSSCs.

Direct seawater electrolysis holds promise for sustainable green hydrogen production, yet its scalability is hindered by cathode fouling from Mg(OH)2 and Ca(OH)2 precipitates and high energy barriers for the hydrogen evolution reaction. Herein, we present a hybrid electrocatalyst, RuNiMo/MO/MN, integrating Ru single atoms with a NiMo, MoO2, and Mo2N heterostructure (NiMo/MoO2/Mo2N) to address these challenges through strong metal-support interactions and a cation-inhibitor strategy. Self-released NH4+ ions sequester local OH- to suppress precipitate formation, preserving active site accessibility, while Ru single atoms facilitate the injection of electrons to MoO2, optimizing H adsorption and reducing the energy barrier for H2 evolution. RuNiMo/MO/MN cathode achieves a low overpotential of 259.2 mV at 10 mA cm-2 and a high Faradaic efficiency of 99.5 %, with 2,000-h durability at 100 mA cm-2 in natural seawater, surpassing commercial Pt/C. Furthermore, RuNiMo/MO/MN | |RuO2 membrane electrode assembly sustains operation at 200 mA cm-2 for over 250 h, with a hydrogen production cost of $1.36 per kg, below the US Department of Energy target of $2 per kg.

We report a detailed examination of multiple negative differential conductance (NDC) features with hysteresis, observed in interband cascade lasers and light emitting diodes made from six different wafers covering an emission wavelength range from 2.7 to about 7 μm. These features arise from resonant tunneling in quantum wells (QWs), can be observed in both forward and reverse biases, and persist up to 160 K and over 300 K, respectively. By comparing features from wafers with a variable number of cascade stages (Ns) and different electron injector doping concentrations, strong correlations are established between the Ns and the number of NDC peaks, as well as between the appearance of forward-bias NDC features and the doping concentration. Under reverse bias, two distinct groupings of NDC peaks appear, which can be plausibly attributed to resonant tunneling through both ground and excited states in QWs. By comparing different internal structures, this tunneling can be isolated to the cascade stages of the emitters. NDC analysis is also shown to be useful as a tool for diagnosing partial internal damage within devices, providing a simple non-destructive way to test device performance.

Steric regulation at the dye/semiconductor interface critically governs charge recombination and interfacial energetics in dye-sensitized solar cells (DSSCs) but remains poorly defined for unsymmetrical squaraine sensitizers. Here, two π-extended unsymmetrical squaraine dyes (AQ1 and AQ2) are designed to clarify how alkyl-chain-induced steric modulation influences aggregation, surface packing, and intramolecular charge-transfer (ICT) dynamics. Both dyes show strong visible-near-infrared absorption and suitable the highest occupied molecular orbital and the lowest unoccupied molecular orbital (HOMO-LUMO) alignment for electron injection into TiO2. In AQ2, branched alkyl substituents provide enhanced steric shielding at the TiO2 interface, suppressing aggregation, modifying interfacial dipoles, and increasing Rrec. Importantly, efficiency gains arise mainly from steric control of interfacial energetics and recombination kinetics rather than aggregation suppression alone. Consequently, AQ2-based DSSCs deliver 7.41% power conversion efficiency with higher Rrec = 11.64 Ω and longer electron lifetime (τ = 8.58 ms) than AQ1, despite lower dye loading. Electrochemical impedance spectroscopy (EIS) and density functional theory (DFT) corroborate suppressed back-electron transfer.

Colloidal quantum dot light-emitting diodes (QLEDs) typically rely on ZnO-based electron transport layers (ETLs), which often suffer from excessive electron injection and an undesirable positive aging effect. Herein, we demonstrate a new class of ZnxCd1-xS alloy nanocrystals as bandgap- and mobility-tunable ETLs for inverted QLEDs. By varying the Zn/Cd ratio, the optical bandgap of the ZnxCd1-xS nanocrystals can be continuously tuned from 2.52 to 3.85 eV, enabling precise alignment of the conduction band minimum with the quantum dot emissive layer. Furthermore, an in situ ligand exchange with 3-mercaptopropionic acid (MPA) is employed to replace the long-chain insulating oleylamine ligand, significantly enhancing the film conductivity by nearly 2 orders of magnitude. MPA-treated Zn0.1Cd0.9S-based QLED achieves a maximum external quantum efficiency of 16.4% and a peak luminance of 139,937 cd m-2, representing an ∼93% enhancement over the untreated device. This work establishes composition- and ligand-engineered ZnxCd1-xS alloy nanocrystals as versatile and efficient ETL platforms for next-generation QLEDs.

ABSTRACT Butyrate, a valuable short‐chain fatty acid, serves as a natural preservative, flavor enhancer, and gut health modulator in the food and feed industries. However, its sustainable microbial production is constrained by the low yield and selectivity inherent to conventional fermentation processes, primarily due to intracellular redox and energy limitations. To address this, we developed a light‐driven probiotic system by integrating in situ biomineralized cadmium sulfide (CdS) nanoparticles with metabolically engineered Clostridium tyrobutyricum . This hybrid interface enables direct injection of photogenerated electrons into cellular metabolism, boosting the intracellular NADH/NAD + ratio by 51% and effectively reprogramming the redox state. Consequently, the system achieved a 33.2% increase in butyrate yield (0.437 vs. 0.328 g/g) and elevated product selectivity from 89.5% to 95.7%. This work demonstrates a green and energy‐efficient strategy for enhancing the bioproduction of food‐grade butyrate, offering a novel platform for advancing light‐powered fermentation in food biotechnology.

Improving the efficiency of photoelectrocatalytic cells relies on precise control of interfacial electron transfer rates to favor the generation of long-lived charge-separated states. Achieving efficient forward electron transfer while suppressing charge recombination remains a central challenge. In this study, we investigate a cobalt-based transition metal complex that undergoes charge transfer-induced spin crossover (CTISC) as a strategy to modulate interfacial charge dynamics in dye-sensitized photoelectrochemical architectures. Ultrafast and nanosecond transient spectroscopy were used to quantify electron injection and dye regeneration. Open-circuit voltage decay measurements were employed to assess the lifetimes of injected electrons under operating conditions. Density functional theory (DFT) calculations were used to estimate the inner-sphere and outer-sphere reorganization energies associated with the redox processes. The results demonstrate that the large inner-sphere reorganization energy associated with spin-state change significantly prolongs charge-separated lifetimes. These findings highlight the potential of spin-state-mediated reorganization as a design principle for suppressing charge recombination and improving the performance of dye-sensitized photoelectrochemical systems.

Abstract This paper investigates the turn-off dVCE/dt controllability of an ultrahigh-voltage SiC P-IGBT. Both simulation and experimental analyses of the inductive-load turn-off process of the SiC P-IGBT were conducted with different gate resistances. Meanwhile, experimental and TCAD simulation results reveal a turn-off dVCE/dt uncontrollability at low Rg. The mechanism is attributed to the collector-gate displacement current, which modulates the Miller voltage relative to the threshold voltage, thereby controlling the turn-off dVCE/dt. When the Miller voltage drops below the threshold voltage, the MOS channel turns off during the Miller plateau. As a result, additional hole and electron injection into the drift region is eliminated, and the turn-off dVCE/dt becomes approximately constant. As Rg increases, the Miller voltage exceeds the threshold voltage, enabling MOS channel turn-on and enhanced hole and electron injection that slows depletion region expansion, thereby showing controllable turn-off dVCE/dt.

Bismuth iodide oxide (BiOI) has significant potential for promoting the repair of infectious nerve defects due to its excellent photoelectric conversion and carrier mobility properties. Nevertheless, their applications are restricted by inefficient near-infrared light absorption and excessive electronic transition barriers. Herein, bismuth (Bi) nanoparticles are hydrothermally deposited on BiOI, which introduces oxygen vacancies (OV) and form a Bi-BiOI Schottky junction, and then added into a poly-L-lactic acid (PLLA) scaffold. Concretely, Bi nanoparticles induce a collective oscillation of free electrons, expanding the photoresponse range. The generated hot electrons are then injected into the built-in electric field of BiOI via the heterojunction, thereby enhancing the photoelectric effect. More ingeniously, OV can introduce defect energy levels, which lower the electron injection barrier and improve electron-hole separation, thus promoting the photocatalytic effect. The results proved that the photoresponse extended to the near-infrared region and that the photoelectricity effect was confirmed by a 50% increase in transient photocurrent and an output voltage of 5 mV. Electrical signals promoting neuronal differentiation were evidenced by 40-fold and 20-fold increases in Nestin/GFAP protein and neural mRNA expression, respectively. ROS production increased by 51.8%, which effectively eradicated biofilms, and penetrated bacteria, inducing GSH depletion and protein leakage. Consequently, the antibacterial rates reached 92.5% (E. coli) and 93.1% (S. aureus).

In solution-processed organic light-emitting diodes (OLEDs), carrier injection imbalance and interfacial quenching persist as major hurdles, primarily due to the hole-dominated transport in polymer-based emitters. Here, we introduce a simple but highly effective post-fabrication strategy for enhancing charge balance and device performance by chemically modifying ZnO nanoparticles (ZnO-NPs) through acetone immersion. This treatment selectively passivates oxygen vacancy-related trap states at the ZnO NPs surface, resulting in improved electron injection and restored hole-blocking behavior, without disrupting the device structure or layer interfaces. Comprehensive analyses, including X-ray photoelectron spectroscopy (XPS), photoluminescence (PL), and transient electroluminescence (EL) measurements, confirm the defect passivation mechanism and its impact on charge injection dynamics. Acetone-treated OLEDs exhibit reduced turn-on voltage, significantly higher luminance (exceeding 44000cd/m2), and enhanced efficiency across all RGB subpixels, while maintaining spectral purity. Furthermore, this method enables scalable fabrication of ultra-high-resolution RGB pixel arrays on a large scale without requiring additional functional layers.

We present a novel series of ruthenium dyes tailored for solar energy conversion. Each dye features a C∧NtBu donor motif, constructed from either imidazole-2-ylidene or benzimidazole-2-ylidene-based N-heterocyclic carbenes (NHCs) linked to p-tbutylpyridine. The C∧NtBu donor set, along with a solitary thiocyanate ligand, augments donor strength, while mono- or tricarboxylic acid-functionalized terpyridyl acceptors complete the coordination sphere and facilitate robust anchoring of the dyes onto TiO2 surfaces. These complexes demonstrate extensive absorption of visible light up to 790 nm and exhibit notable molar absorptivity of 84,200 M-1 cm-1 at 500 nm. Dyes based on benzimidazole-2-ylidene display protracted excited-state lifetimes (212-210 ns) and possess energy levels that are ideal for electron injection into the TiO2 conduction band. Upon integration into dye-sensitized solar cells, this dye yields photocurrent densities of 25 mA cm-2. The synergistic effect of NHC and p-tbutylpyridine donors serves to lower the Ru2+/3+ oxidation potential to 0.66 V below the I-/I3- redox couple, thereby promoting efficient dye regeneration. Devices employing these dyes achieve power conversion efficiencies up to 7.09%, exceeding the N3 and N749 benchmarks under identical conditions. This paper aims to elucidate the principles guiding the design of NHC-based ruthenium photosensitizers for optimal solar energy conversion.

The optoelectronic performance of organic light-emitting diodes (OLEDs) is critically governed by charge injection from electrodes into organic layers, where significant energy barriers at the interfaces often impede efficient charge injection. These barriers disrupt the balance between hole and electron injection in the emitting layer, thereby limiting device optoelectrical performance. Conventional electron injection layers (EILs), such as lithium fluoride (LiF) or ultrathin metal layers, often exhibit limited injection efficiency when used with certain metals, including silver. In this work, we propose a lead-free perovskite thin film, RbYbI3, as an efficient EIL for OLEDs. Deposited via vacuum evaporation, a 5-nm-thick RbYbI3 layer induces a 630-mV surface potential shift at the interface between the organic layer and the metal electrode. First-principles density functional theory calculations also confirm that RbYbI3 exhibits termination-dependent surface dipole formation, thereby lowering the effective injection barrier relative to LiF. This facilitates efficient electron injections across various organic semiconductors without requiring additional interface engineering. Furthermore, RbYbI3 is compatible with both aluminum and silver cathodes, unlike LiF, which exhibits electrode-material limitations. When applied to blue-emitting OLEDs, the device with RbYbI3 exhibits a lower turn-on voltage by 0.4V and a higher external quantum efficiency (EQE) of 19.5% than the control using LiF (EQE of 17.7%). Similarly, green OLEDs with RbYbI3 maintained superior efficiency at high luminance, with a maximum EQE of 23.0% and 20.7% at 10000cd m- 2, compared to 22.0% and 15.8% at 10000cd m- 2 for the LiF-based control device. The perovskite-based EIL is readily integrated into standard OLED fabrication processes, providing a universal and practical strategy to overcome the limitations of conventional EILs and enabling the development of high-performance OLEDs.

Abstract We numerically investigate a scheme for generating ultralow-emittance electron beams using hydrodynamic optical-field-ionization (HOFI)-induced shock injection in laser wakefield acceleration (LWFA). A steep density down-ramp formed by the HOFI process enables electron injection at low laser amplitude a 0 , reducing transverse forces and favoring longitudinal injection to minimize the beam emittance. Particle-in-cell simulations demonstrate the production of high-quality electron beams with a charge of 28 pC , an energy of approximately 350 MeV , an rms energy spread of about 3%, and a normalized projected emittance of about 80 nm rad . Unlike mechanically driven shocks commonly used in LWFA, the HOFI-induced shock exhibits superior stability, enabling precise control over the electron injection process. Moreover, because injection occurs where a 0 is relatively low and slowly varying, the scheme shows enhanced tolerance to laser energy jitter. This approach provides a promising pathway for generating high-quality electron beams suited for downstream applications such as GeV-class plasma accelerators and free-electron lasers.

Trap passivation and injection barrier tuning via self-assembled dipole interfaces for starlight-sensitive organic photodetectors

Abstract We have proposed and analyzed a quantum cascade laser operating at λ = 1.27 μm based on a Si/CaF2 heterostructure, and successfully demonstrated room-temperature electroluminescence (EL). Threshold current density was calculated as a balance of optical gain and loss according to waveguide structure design; population inversion was confirmed by analyzing inter-subband relaxation time τ_21 and extraction time τ_1 (τ_21 ∶ τ_1=2:1). Two periods of active layer were epitaxially grown on an n-Si (111) layer of a silicon-on-insulator (SOI) substrate equipped with conduction layer for electron injection and waveguide by molecular beam epitaxy (MBE). Fourier-transform infrared spectroscopy confirmed a distinct three-peak EL emission, with intensity increasing nearly linearly with the injected current density; and centered around 1.25 μm because of thickness ±1 ML fluctuation of thin films, which is suspected to be caused in process of epitaxy. Furthermore, a systematic wavelength shift of the emission peaks under increasing applied voltages was clearly identified, which can be consistently explained by the Stark shift in the transition quantum well induced by the applied bias that tilts the barrier tops, effectively making the barriers thinner at higher bias, producing the same effect as reducing the barrier thickness and leading to a wavelength shift.

ABSTRACT The global energy transition is stimulating the design and advancement of high-efficiency photovoltaic materials. In this research, we have focused particularly on the utilisation of nine quinoxaline-based organic dyes (M1–M9) which are used as sensitisers in dye-sensitised solar cells. We performed simulations based on density functional theory (DFT) and time-dependent DFT (TD-DFT) in order to determine energy levels, ultraviolet-visible (UV-Vis) absorption parameters, the free energy of electron injection and the global descriptors, as well as interfacial adsorption on the TiO2 semiconductor. The results confirmed that all the investigated compounds exhibit a small band gap for all the investigated compounds, with values ranging from 1.65 eV to 2.59 eV. This enables favourable charge transfer and visible light absorption. Additionally, wavelengths are extracted between 360 and 560 nm following TD DFT computations, highlighting that M3, M5 and M6 dyes have high oscillator strengths and excellent light-harvesting efficiencies.

Abstract To explore potential pathways for performance enhancement, this study investigates the effect of an external electric field on porphyrin-based dye-sensitized solar cells (DSSCs). Focusing on the porphyrin-based Dye 31, we systematically investigated the electronic structure characteristics of the dyes and Dye@TiO 2 system, as well as the regulatory mechanism of the local electric field on some parameters. Comparative analysis revealed that Dye 31 exhibits superior overall performance over Dye 25 across multiple metrics, featuring a smaller energy gap (E g ), enhanced intramolecular charge transfer (ICT), and a longer excited-state lifetime ( τ ). The 31@TiO 2 system exhibits significant charge separation, high electron injection, and better optoelectronic performance. Furthermore, the influence of local electric field strength on energy levels and gaps, spectra and charge transfer was discussed. This work provides insight into the photoelectric performance of chlorophyll derivative dyes and the mechanism of electric field influence.

The charge-transfer-to-solvent (CTTS) states of aqueous halides serve as prototypical systems for probing electron-transfer dynamics. In the photogeneration of hydrated electrons [e-(aq)] from iodide ions [I-(aq)], the concomitant formation of I2 and I3- as primary byproducts severely limits the e-(aq) quantum yield. Although the formation of these byproducts has been extensively studied, the post-photoexcitation dynamics of I3-(aq), particularly the competition between molecular dissociation and electron ejection, remain unclear and warrant further investigation. In this paper, we employ time-dependent density functional theory calculations to confirm that the experimentally observed absorption peak at ∼5.5eV originates from a CTTS state of I3-(aq). Furthermore, abinitio molecular dynamics simulations in excited states reveal that photoexcited I3-(aq) can generate a short-lived e-(aq) prior to dissociation. Crucially, the nascent I2 fragment efficiently traps the ejected electron via its low-lying σ* molecular orbital (MO). To overcome this bottleneck, we propose a strategic solution: introducing an electron-donating protic solvent (e.g., ethylene glycol). This approach simultaneously suppresses I3- formation and elevates the unoccupied MO energy level of I2, thereby mitigating its electron-trapping capability and ultimately enhancing the e-(aq) quantum yield from I-(aq). This work establishes a novel design principle, modulating solute MO energetics, for optimizing electron injection efficiency in liquid-phase systems.