Journal of Materials Chemistry C最新文献

Although crystallographic engineering of perovskite single crystals offers a promising route to optimize optoelectronic performance, the intrinsic charge transport mechanisms governing facet-dependent anisotropy remain poorly understood. Herein, we resolve this issue through comparative analysis of stoichiometry-controlled MAPbI₃ single crystals with dominant (100) and (001) facets. The PbI₂-terminated (001) facet achieves enhanced atmospheric stability via oxygen-mediated passivation and reduced hydration susceptibility, contrasting sharply with the air-sensitized MAI-dominated (100) surface. Bulk characterization further identifies 18% higher mechanical hardness and 15% lower trap density in (001)-oriented crystals compared to their (100) counterparts. Synergistically, the (001) facet exhibits an 18% elevated ion migration activation energy (0.59 eV) and superior Hall effect mobility (7.3 cm² V⁻¹ s⁻¹ at 180 K), surpassing (100) by 1.55×. Temperature-dependent field-effect transistors corroborate this anisotropy, yielding a peak mobility of 14.7 cm² V⁻¹ s⁻¹ for (001) versus 8.3 cm² V⁻¹ s⁻¹ for (100). Our findings establish crystallographic orientation as a pivotal design parameter, with PbI₂-terminated (001) facets offering atomic-scale insights for advancing high-efficiency perovskite optoelectronics.

White afterglow materials have attracted considerable attention owing to their promising applications in illumination displays, biological imaging and information encryption. However, research on high-efficiency photoluminescence (PL) and afterglow dual-mode white emission remains rare. Here, we report a simple strategy to fabricate carbon dots (CDs)-based PL and afterglow dual-mode white emission materials, in which (3-aminopropyl) trimethoxysilane (APTMS) and rhodamine 6G (Rh6G) are combined as precursors through a hydrothermal reaction. After the subsequent modification with urea, dual-mode white emission CDs (Si-CDs@u) exhibiting Commission Internationale de l’Eclairage (CIE) coordinates of (0.38, 0.41) for PL and (0.40, 0.43) for afterglow were successfully synthesized, achieving a high PL quantum yield (QY) of 65 ± 1%. Experimental analysis confirms that the short-wavelength emission originates from room temperature phosphorescence (RTP) of APTMS-derived CDs, whereas the long-wavelength emission arises from delayed fluorescence via energy transfer between the RTP-active CDs and subluminophores on their surface. Finally, we presented the application of Si-CDs@u in the white-light emitting diode and afterglow display fields.

As a cutting-edge research direction in neuromorphic devices, interface-type (IT) memristors leverage interfacial engineering for resistive switching owing to the filament-free switching, low power dissipation, and high scalability. However, the trap states governing the interfacial Schottky barrier often exhibit a discrete and stochastic distribution. This study utilizes Xe ion irradiation with a fluence of 5 × 10¹⁰, 1 × 10¹¹, 5 × 10¹¹, 1 × 10¹² and 3 × 10¹² cm⁻² to introduce defects near the surface of Nb:SrTiO₃ (NSTO), thereby controlling the interface Schottky barrier. The device with the fluence of 1 × 10¹² cm⁻² maintains good stability and excellent cyclic endurance characteristics, and increases the on/off ratio by an order of magnitude (from 10⁵ to 10⁶). Meanwhile, it can well simulate the synaptic function and in the neurological system, the recognition accuracy of images reaches 94.4%. These results indicate that ion irradiation can improve the resistance of IT memristors and be used in artificial synapses to establish the next generation of neural morphology calculation.

This study presents delocalization and bandgap engineering in defective MoS₂ by metal ion doping. Due to inevitable defects, MoS₂ field-effect transistors (FETs) exhibit unstable electrical characteristics. However, doping with indium, gallium, zinc, and oxygen ions using an IGZO layer enhances the stability and electrical performance of MoS₂ FETs and remarkably enables efficient detection of near-infrared light. Chemical and structural analyses reveal that metal ions diffuse into defective MoS₂, forming a few-nanometer-thick doped MoS₂ layer with a delocalized electronic structure and a reduced bandgap, and also a quasi-quantum well structure made of MoS₂, doped MoS₂, and IGZO. Current–voltage analyses and ab initio density functional theory calculations reveal that, due to the delocalized doped layer and the quasi-quantum-well structure, charge transport is confined to the layer, leading to remarkable near-infrared detection properties and band-like charge transport. We thus regard the doping-induced delocalization and bandgap engineering in defective MoS₂ as a promising strategy for next-generation optoelectronic applications.

The call for a green economy has accelerated research and development of energy-saving optoelectronic devices. The choice of photoelectric material and the design of the device configuration are crucial for achieving high device performance. In this study, we investigated the photoelectric response behaviors of van der Waals (vdW) heterostructure photodetectors by employing a type-II MnPSe₃/MoS₂ heterojunction for charge carrier transport. Two types of device architecture were designed, one has a vertically stacked heterostructure with the photogenerated carriers transferring in an out-of-plane direction in the overlapped area of both materials; the other utilizes the photogating effect using the top MoS₂ as the photogate for the carrier distribution modulation and MnPSe₃ at the bottom as the carrier transport channel. Both PDs demonstrated a broadband photoelectric response in the range of 254–1020 nm under the biased condition. Additionally, the former device exhibited distinct self-powered behavior with a spectral detection range spanning from 365 nm to 635 nm, which was attributed to the higher charge carrier separation efficiency resulting from the built-in electric field of the MnPSe₃/MoS₂ heterojunction and the asymmetric barrier heights of the two metal–semiconductor interfaces. This study reveals the possibility of harnessing the vdW MnPSe₃/MoS₂ hybrid in low-power-consuming optoelectronic devices and its application potential in broadband photoelectric detection.

Cadmium telluride (CdTe) nanoparticles have become an interesting material for various research applications due to their outstanding optoelectronic properties and structural flexibility. In this study, four La-doped CdTe (LCT) nanomaterials were grown using the hydrothermal method to examine the effect of La addition on their optical, structural, and optoelectronic characteristics. With increasing La concentration, a morphological transition from nanoparticles to a nanoparticle–nanorod hybrid structure was shown by field emission scanning electron microscopy (FESEM) analysis. The cubic CdTe phase was validated by X-ray diffraction (XRD) patterns, and the material's unique vibrational modes were revealed by Raman spectroscopy. The chemical composition and oxidation states of the constituent elements were further revealed by X-ray photoelectron spectroscopy (XPS) spectra. With increasing La content, the optical bandgap showed red-shift behaviour, decreasing from 2.17 eV to 2.06 eV, while the refractive index (n) increased from 2.57 to 3.44. Photoresponse studies showed that all samples exhibited increased photocurrent under illumination compared to dark conditions. Additionally, all samples exhibited reverse saturable absorption (RSA) behaviour, as confirmed by nonlinear optical (NLO) analysis, which revealed positive nonlinear absorption coefficients. These results indicate that La-doped CdTe nanostructures, particularly the LCT-0 sample, have considerable potential for use in nonlinear optical devices and high-performance photodetectors.

Transparent conducting films (TCFs) were fabricated through the transformation of silk fibroin (SF), a renewable natural biopolymer, into carbon nanosheets (CNSs) via a catalyst free carbonization process. By adjusting the SF concentration, spin coating rate, and heat treatment temperature, the thickness of the CNS films was tuned from 3.7 to 38.8 nm, while maintaining uniform and smooth surfaces with R_a values between 0.28 and 0.62 nm. Structural analyses showed that pseudo-graphitic nanodomains gradually developed as the heat treatment temperature increased, and these changes directly influenced the optical and electrical properties. The optimized CNS films exhibited an optical transmittance of up to 95.7% at 550 nm and an electrical conductivity of 4.4 × 10² S cm⁻¹, achieving a balanced combination of transparency and conductivity comparable to other solution-processed carbon electrodes. This study provides a scalable and sustainable method for producing ultrathin and flexible carbon-based TCFs and offers clear guidance on the relationships among processing conditions, structural features, and the resulting material properties using silk fibroin as a renewable precursor.

Transition metal doping is commonly used for altering the properties of solid-state materials to suit applications in science and technology. Partially filled d-shells of transition metal atoms lead to electronic states with diverse spatial and spin symmetries. Chromium(III) cations have shown great potential for designing laser materials and, more recently, for developing spin qubits in quantum applications. They also represent an intriguing class of chemical systems with strongly correlated multi-reference excited states, due to the d³ electron configuration. These states are difficult to describe accurately using single-reference quantum chemical methods such as density functional theory (DFT), the most commonly used method to study the electronic structures of solid-state systems. Recently, the periodic effective Hamiltonian of crystal field (pEHCF) method has been shown to overcome some limitations arising in the calculations of excited d-states. In this work, we assess the suitability of DFT and pEHCF to calculate the electronic structure and d–d excitations of chromium(III) dopants in wide band gap host materials. The results will aid computational development of novel transition metal-doped materials and provide a deeper understanding of the complex nature of transition metal dopants in solids.

Exciplex systems based on deuterated organic semiconducting molecules provide a promising strategy to enhance the performance of organic light-emitting diodes (OLEDs). Although the enhancement of OLED performance by utilizing a partially deuterated exciplex system has been reported, the impact of deuteration of the organic semiconducting molecule on exciplex dynamics has not been fully characterized. Here, we investigate the impact of deuteration of the electron-donor molecules (mCP-d₂₀ : 1,3-dicarbazole-benzene-d₂₀) on the exciplex dynamics in the mCP-d₂₀ : 2,4,6-tris[3-(diphenylphosphinyl)phenyl]-1,3,5-triazine (PO-T2T) co-deposited films. Compared to the co-deposited films based on undeuterated mCP, the mCP-d₂₀:PO-T2T films exhibited a 1.5-fold increase in photoluminescence quantum yield (PLQY) with prolonged delayed emission lifetime. Temperature-dependent kinetic analyses for electron transition processes revealed that the enhancement of PLQY in the mCP-d₂₀:PO-T2T films originates from the suppression of thermally activated nonradiative decay from the excited charge-transfer triplet state by donor deuteration. Consequently, the OLED based on the deuterated exciplex system demonstrated a higher external quantum efficiency than those employing undeuterated donors.

Ti₃C₂ MXene (Ti₃C₂T_x), a two-dimensional transition metal carbide, is widely regarded as a highly promising cocatalyst for photocatalytic hydrogen evolution due to its high electrical conductivity and tunable surface terminations. However, the excessively strong Ti–H bond strength in conventional Ti₃C₂ MXene leads to unfavorable hydrogen desorption kinetics, which is further exacerbated due to an overabundance of highly electronegative F-terminations on Ti₃C₂T_x from the F-containing etchant (Ti₃C₂F_x). This study proposes constructing a NiOOH–Ti₃C₂F_x heterojunction to facilitate electron transfer from NiOOH to Ti₃C₂F_x for increasing the Ti 3d antibonding orbital occupancy state. The NiOOH–Ti₃C₂F_x/CdS photocatalysts are prepared through a two-step process, including the initial formation of NiOOH on Ti₃C₂F_x by a precipitation reaction and the subsequent in situ growth of CdS on the NiOOH–Ti₃C₂F_x surface. Photocatalytic hydrogen evolution tests demonstrate that the NiOOH–Ti₃C₂F_x/CdS photocatalyst achieves a significantly enhanced hydrogen production rate of 2.42 mmol h⁻¹ g⁻¹, representing 7.8 times and 4.94 times improvements over pristine CdS and Ti₃C₂F_x/CdS, respectively. DFT calculations and spectroscopic analyses reveal that the electron transfer from NiOOH to Ti₃C₂F_x increases Ti 3d antibonding orbital occupancy, thereby weakening the Ti–H_ads bond. This study provides critical insights into modulating the hydrogen adsorption capacity at Ti sites for efficient solar fuel production.