Physics

ABSTRACT The selective oxidation of hydrocarbons with molecular oxygen (O 2 ) is a pivotal but energy‐intensive process, with the primary energy consumption arising from the activation of the robust O═O bond. While emerging organic photocatalysts offer a sustainable route for O 2 activation under mild conditions, the prevailing mental model often involves first generating H 2 O 2 as an intermediate oxidant. Consequently, the scalable construction of efficient metal‐free systems capable of directly coupling O 2 activation with selective transformations remains a formidable challenge. Herein, a 3D, spatially π‐extended triphenylene framework (HCP‐TP‐FDA) is synthesized scalably via a simple Friedel–Crafts reaction. This hyper‐cross‐linked polymer bypasses complex monomer design and exhibits outstanding photocatalytic performance in O 2 activation. This unique capability enables efficient H 2 O 2 production (5.57 mmol g −1 h −1 ) and selective oxidation of cyclohexane to KA oil (515 µmol g −1 h −1 ) and the hydroxylation of phenol to dihydroxybenzene (167 µmol g −1 h −1 ). Mechanistic studies reveal that the synergy between electron‐rich triphenylene units and 3D conjugation facilitates directional charge migration along organized π–π stacks—a mechanism reminiscent of natural light‐harvesting systems. This process effectively promotes exciton dissociation and O 2 activation, leading to the versatile generation of reactive oxygen species.

ABSTRACT Defect‐induced lattice distortion and thermally induced lattice expansion result in lattice strains in the perovskite film. Suppressing the lattice strain is significant for improving efficiency and stability of perovskite solar cells (PSCs) but remains challenging. Herein, we report a strain inhibition strategy by treating the intermediate‐state perovskite (Inter‐PVK) film pre‐annealed at a low temperature using a boronic acid‐based molecule. The boronic acid group interacts with ionic defects on the surface of the Inter‐PVK film, in favor of reducing defect‐induced lattice distortion in the final‐state perovskite film during its downward growth process. The interaction also immobilizes organic components, preventing their volatilization and consequently inhibiting the lattice expansion. Both aspects synergistically mitigate the lattice strain throughout the entire perovskite film. The resultant low‐strain perovskite film enables an efficiency of 26.32% for inverted PSCs (certified 26.20%) and 25.57% for regular PSCs, respectively. Moreover, the devices retain 94% of their initial efficiency after 1500 h of continuous 1‐sun light soaking. Our work provides a new strategy for regulating strains in perovskite films to enhance PSC performances.

ABSTRACT Monolithic perovskite/silicon tandem solar cells are highly attractive due to their potential for high power conversion efficiency (PCE). In tandem solar cells, the perovskite top cell and silicon bottom cell are connected via a recombination layer, and the quality of this interface directly affects carrier transport and recombination. However, in silicon heterojunction (SHJ) cells–particularly on micro‐pyramidal (∼600 nm‐thick) textured surfaces, optical losses in the composite layer and non‐uniform coverage of the self‐assembled monolayer (SAM) remain challenging. Here, we investigated the optoelectronic properties of indium tin oxide (ITO) composite layers with thickness ranging from 2 to 30 nm, by optimizing the intermediate composite layer, optical losses in perovskite/silicon tandem solar cells were effectively reduced, and surface potential uniformity was enhanced. We selected an ultra‐thin (8 nm‐thick) ITO layer modified with nickel oxide (NiO x ), which was implemented as a composite interconnect, with a Poly‐SAM layer employed to realize these enhancements. Compared to the reference thickness, the optimized device exhibited an increase in short‐circuit current density of 0.85 mA cm −2 , achieving a high value of 20.82 mA cm −2 , and a power conversion efficiency of 31.80 % was achieved, and 96 % of the initial PCE was retained after 500 h of maximum power point tracking.

Abstract Capacitance, photon detection probability (PDP), and dark count rate (DCR) constitute the primary performance metrics for single-photon avalanche diodes (SPADs) in weak-light detection applications. Understanding their interdependencies and trade-offs is essential for optimal device design, particularly as miniaturization and integration trends intensify. This work investigates the size-dependent performance characteristics of two distinct SPAD structures (STR A and STR B) fabricated by a standard 0.18-μm BCD process. Through combined experimental measurements and TCAD simulations, we systematically analyze the basic coupling mechanism between device size and these three parameters. It establishes a quantitative relationship among junction size and device performance, and introduces the edge ratio metric as a design parameter. providing practical guidelines for SPAD integration and high-precision timing detection.

We present a high-speed infrared spectroscopic ellipsometer using a tunable quantum cascade laser (QCL), leveraging its high brightness for potential in situ and in-line monitoring applications. The instrument employs a dual-rotating-element configuration comprising an achromatic Fresnel rhomb-type rotating compensator and a rotating analyzer, enabling acquisition of 3 × 4 Mueller matrix elements over a wavelength range defined by the installed QCL laser modules. We demonstrate the measurement speed of the QCL ellipsometer and its advantages relative to conventional Fourier-transform infrared ellipsometry through a series of case studies, including measurements of complex molecular vibrations of acrylic and polycarbonate, anisotropic phonon absorption of LiNbO3 single crystal, and its temperature-dependent response. Additionally, we perform time-dependent measurements during the thermal growth of an SiO2 film on Si, highlighting the instrument's capability for real-time process monitoring.

The effects of scattering channels in high operating temperature terahertz quantum cascade laser structures are studied. The electron transport is calculated using a density matrix Monte Carlo method, where the scattering channels are isolated to determine their effects by including and excluding each channel in the transport calculations. Scattering channels leaking to the continuum and from the longitudinal-optical phonon interaction are considered. All channels investigated except one are found to decrease the maximum operating temperature, and only phonon backscattering to the upper lasing state enhances thermal performance. Improving the isolation of scattering channel states is expected to further increase the operating temperature, with thermal backfilling to the lower lasing state dominating.

Electron emission from boundaries is ubiquitous in radio-frequency capacitively coupled plasmas (RF-CCPs) and can exert a significant influence on discharge characteristics. In this work, particle-in-cell Monte-Carlo collisions (PIC-MCC) simulations with an external circuit are performed to investigate a conduction-current-dominated RF-CCP mode, termed the inverted RF-CCP, which is induced by strong boundary electron emission. In this mode, the displacement current becomes negligible, and the conduction current dominates in both bulk plasma and sheaths, as opposed to the classic RF-CCPs. The inverted RF-CCP also features weak resistive sheaths, and the plasma impedance is dominated by a resistive–inductive bulk region due to sheath inversion. Parametric scan of neutral pressure reveals the origin of the observed phase behavior. These findings provide practical methods for diagnosing the inverted RF-CCP, based on its distinctive impedance signature without direct sheath diagnostics. Additionally, we show that unbalanced electron emission can generate discharge asymmetry, enabling a unidirectional ion flow between electrodes.

Hard carbons (HCs) are promising anodes for sodium-ion batteries (SIBs) but suffer from irreversible Na⁺ trapping, inadequate rate capability, and compromised low-temperature performance, primarily due to microstructural defects and suboptimal surface chemistry. Herein, an in situ-transformation carbonization strategy is proposed to synthesize surface low-concentration N, P-doped hard carbons (NP-HCs) for high-rate and low-temperature SIBs. A heteroatom-enriched polyphosphazene is conformally coated onto poplar wood precursors, with triethylamine playing a dual-function role in facilitating polymerization and precursor modification. This strategy endows the NP-HCs with a tailored interfacial environment for fast Na⁺ desolvation and transport, while establishing a bulk environment featuring abundant closed pores and expanded interlayer spacings. Consequently, NP-HCs deliver an ultrahigh reversible capacity of 428.8 mAh g^-1 and outstanding rate capability (272.6 mAh g^-1 at 10 C). Notably, remarkable low-temperature performance is achieved, with exceptional rate capability and cycling stability (93.1% capacity retention over 1200 cycles) at -20°C, underscoring their robustness under extreme conditions. Operando/ex situ characterizations coupled with computational studies reveal Na-storage mechanisms and accelerated kinetics, offering critical insights for high-performance HCs.

Lithium-rich manganese-based oxides (LRMO) suffer from rapid capacity decay, mainly driven by interfacial instability and bulk structural degradation associated with Jahn-Teller (J-T) distortion in Mn³⁺-rich regions. Such distortion accelerates surface oxygen activity, triggers nonuniform cathode electrolyte interphase (CEI) formation along with promoted parasitic reactions. Herein, we develop an electrolyte‑induced interfacial/bulk dual regulation strategy that enables negligible capacity decay in Li‑rich cathodes via coordinated interfacial/bulk regulation. In situ characterizations combined with interfacial compositional analyses confirm the dynamic formation of a thin, uniform, and robust LiF/LiBO₂-rich CEI, which stabilizes surface oxygen species and suppresses interfacial side reactions. Meanwhile, local structural analyses combined with theoretical calculations reveal that fluorinated molecules regulate Mn into a low-spin configuration, thereby alleviating J-T distortion and preventing bulk structural degradation. Benefiting from this dual induced interfacial-bulk stabilization effect, LRMO||Li cells deliver an initial capacity of 219.6 mAh g^-1 and retain 97.6% of their capacity after 400 cycles. This work provides a new pathway toward electrolyte-mediated dual stabilization and demonstrates the feasibility of mitigating capacity decay in Li-rich cathodes via electrolyte-induced interfacial/bulk regulation.

The application of organic electronics relies on reliable material manufacture. Owing to their multiscale structural characteristics, organic electronic materials face great opportunities and challenges in some unique applications compared with silicon-based semiconductors. Understanding the relationships among material structure, processing and properties is highly desirable for the multiscale manufacturing of organic functional devices. Recently, researchers have made significant progress in this field, achieving reliable fabrication across multiple scales, from molecular-scale devices to micro/milli-scale wearable systems and macroscale organic solar cell modules, to meet the specific requirements of various application scenarios. This review aims to summarize the latest advancements in multiscale manufacturing of organic electronic materials. It introduces multiscale structures and properties of organic semiconductors, with an emphasis on elucidating the structure-property relationship. Subsequently, different technologies for multiscale manufacturing and their advanced applications in organic electronics are discussed. Finally, potential challenges and prospects for the multiscale manufacture of organic electronic materials are proposed. This review could help in choosing appropriate manufacturing technologies to achieve optimal performance of organic electronic devices based on the properties of organic materials.

Electron-enhanced atomic layer deposition (EE-ALD) of amorphous, tunable titanium carbonitride (TiCxNy) films was obtained at low temperatures. The TiCxNy EE-ALD was achieved using sequential exposures of tetrakis(dimethylamido)titanium (TDMAT) and low-energy electrons in the presence of a continuous NH3 reactive background gas (RBG). The composition of the TiCxNy films was tuned by varying the NH3 background pressure and the electron exposure time. The TiCxNy EE-ALD was performed by utilizing a hollow cathode plasma electron source (HC-PES). The HC-PES delivered a high electron flux into background gases at pressures up to several mTorr. TDMAT was used as the source of Ti, C, and N. The NH3 RBG served as both a source of additional N and a method for the removal of C from the TiCxNy films. The TiCxNy EE-ALD film growth was monitored using in situ ellipsometry. The TiCxNy EE-ALD was conducted at low temperatures that never exceeded 130 °C, using NH3 pressures from 0 to 3 mTorr. The C content in the TiCxNy films could be tuned using the NH3 RBG pressure. Lower NH3 pressures led to the incorporation of more C into the TiCxNy films. The C:Ti ratio varied from ∼0.3 to ∼0.05 versus NH3 RBG pressure, as measured by X-ray photoelectron spectroscopy (XPS), at a constant electron exposure time of 10 s. Electron exposure time was also used to modulate the C content in the TiCxNy films. Shorter electron exposures led to more C incorporation. The C:Ti ratio varied from ∼2 to ∼0.1 versus electron exposure time, as measured by XPS at a constant NH3 background pressure of 2 mTorr. In situ 4-wavelength and ex situ spectroscopic ellipsometry were able to estimate electrical resistivities for the TiCxNy films. Resistivity was reduced from >2000 μΩ cm to ∼200 μΩ cm with decreasing C content. X-ray reflectivity (XRR) measurements were able to determine film densities. The film density for TiN films was 4.6 g/cm3, and the film density decreased with increasing C content. The C content in the TiCxNy films could also be varied using a CH4 RBG. Carbon could be added by carbon EE-chemical vapor deposition (EE-CVD) using electron exposures together with a CH4 RBG. The carbon could also be removed by carbon EE-chemical vapor etching (EE-CVE) using electron exposures together with NH3 RBG. The C content in the TiCxNy films was difficult to control using a supercycle approach with TiN EE-ALD and carbon EE-CVD.

Efficient, flexible, and solution-processable organic polymeric scintillators are urgently needed for diverse applications. However, conventional organic scintillators face intrinsic limitations in their exciton utilization efficiency and X-ray absorption capability. Herein, we introduce a design strategy for high-performance polymer scintillators by covalently integrating multiresonance thermally activated delayed fluorescence emitters into a bromine-functionalized copolymer matrix through facile free-radical copolymerization. The resulting copolymer scintillators exhibit enhanced exciton utilization through efficient reverse intersystem crossing and markedly improved X-ray absorption, owing to bromine incorporation. The optimized material achieves bright radioluminescence peaked at 500 nm, with a narrow full width at half-maximum of 46 nm. This scintillator achieves a high spatial resolution of 10 lp/mm, as determined by a standard line-pair test pattern, along with an exceptionally low detection limit of 301 nGy/s. Practical X-ray imaging applications confirm its capability to distinctly visualize intricate internal structures, validating its potential for clinical and industrial applications. This work establishes a versatile molecular design strategy for the development of advanced organic scintillators.

To realize highly optimized properties and performance of semiconductor photocatalysts, precise control over their composition and the site occupancy of multiple cations and anions is essential. This study demonstrates that Bi2YO4Cl, a multicationic oxyhalide photocatalyst, exhibits markedly higher activity when isovalent Bi-for-Y substitution is suppressed by simply controlling the precursor stoichiometry. The flux synthesis of Bi2YO4Cl under stoichiometric conditions induces the partial substitution of Bi3+ into Y3+ sites, creating localized states near the valence band maximum, which act as hole traps and hinder efficient charge carrier utilization. Using an excess of Y2O3 during the synthesis suppresses the undesired Bi-for-Y substitution, leading to markedly higher H2 and O2 evolution rates under visible-light irradiation. This study highlights the critical importance of precise cation placement for maximizing the photocatalytic performance of multicationic photocatalysts.

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