Search Results (424)

Indium Tin Oxide (ITO) is one of the most widely used ohmic materials for fabricating ohmic layers in thin-film solar cells. ITO thin layers have reached almost the maximum theoretical conductivity and the lowest practical resistivity. Along with indium’s toxic environmental impact and the high cost of materials, these are the reasons why new materials for efficient, cheaper thin-film transparent ohmic layers are being examined. One of those materials is copper-doped zinc oxide (ZnO:Cu). In this paper, we present a new approach to copper-doped zinc oxide fabrication methods, based on the modern authorial Physical Vapor Co-Deposition technique, which involves optimizing Cu concentration to fine-tune crystal structure, optical band gap, and electrical properties, creating n-type TCOs essential for efficient charge transport in next-generation thin films perovskite solar cells. Full article

Metal-chalcogenide compounds with perovskite-type compositions have drawn increasing attention for their optical properties for solar energy conversion. Herein, a new α-type polymorph of the ternary sulfide SrHfS₃ is described, crystallizing in the NH₄CdCl₃ structure type. The yellow-colored plate-shaped crystals were synthesized at 1173 K using an elemental tin flux in an evacuated sealed tube. Its crystal structure was characterized at room temperature using single crystal X-ray diffraction to form in the orthorhombic Pnma space group, with the refined cell parameters of a = 8.5041(4) Å, b = 3.8004(2) Å, c = 13.8935(6) Å, and V = 449.02(4) ų. The structure comprises five independent crystallographic sites, having one Sr, one Hf, and three S sites. The structure can be described as containing one-dimensional chains of distorted HfS₆ octahedra extending down the b-axis to form ${\displaystyle \genfrac{}{}{0pt}{}{1}{\infty }}[$HfS₃]²⁻ strips of edge-sharing octahedra. The Sr atoms act as charge-balancing space fillers in the structure. High-purity bulk samples of α-SrHfS₃ could be prepared for measurement of its bandgap by optical diffuse-reflectance spectroscopy, showing a direct bandgap of 2.1(1) eV. Results of electronic structure calculations are consistent with this bandgap and type. The conduction and valence band edges stem from the respective empty Hf d-orbitals and the filled S p-orbital states. In summary, crystal growth of the α-type polymorph of SrHfS₃ has been demonstrated using a Sn flux approach, which can facilitate future broader synthetic explorations at lower temperatures. Full article

This study presents an all-optical artificial synapse based on 2D perovskite materials for neuromorphic visual simulation. While conventional optoelectronic synapses, which integrate memory and processing, are prevalent in this field, their inherent optical-to-electrical conversion during signal processing incurs significant energy costs. In contrast, our proposed device operates purely in the optical domain. Under ultraviolet–visible light control, the change in light transmittance of this device can simulate various key biological synaptic plasticity behaviors, including paired-pulse facilitation and learning ability. By integrating these devices into a 28 × 28 synaptic array, we constructed an artificial neural network that mimics the experience-driven enhancement characteristic of human visual perceptual learning. Under light-responsive regulation, the system optimized image recognition learning behavior, and after multiple training sessions, the recognition accuracy stabilized above 97%. This study is based on two-dimensional perovskite materials and provides a new material platform for realizing intelligent visual systems with adaptive learning capabilities. Full article

In this work, the electronic, structural, and magnetic properties of Ti-, V-, Cr-, Mn-, and Ni-doped AgZnF₃ perovskites are systematically investigated using the Korringa–Kohn–Rostoker method combined with the coherent potential approximation (KKR-CPA) within the generalized gradient approximation (GGA). Transition metal dopants (Ti and V) at a concentration of 5% substituting the Zn site introduce 3d states that cross the Fermi level in the majority-spin channel, resulting in half-metallic behavior. Ferromagnetic stability is predicted for Ti-, V-, Cr-, and Mn-doped AgZnF₃ at a doping concentration of 5%. The TM-doped AgZnF₃ alloys exhibit noticeable variations in exchange splitting between the t₂g and e_g states of the TM-3d orbitals. In Ti-doped AgZnF₃, the calculated spin magnetic moments follow the expected trend based on crystal-field splitting theory. Furthermore, a clear correlation is observed between the nature of the transition metal dopant (Ti, V, Cr, Mn, and Ni) and the total magnetic moment of the system. Full article

Mechanical properties of lead-free hybrid perovskites have attracted growing interest because of their significance in future eco-friendly optoelectronic applications. However, there are very limited studies about the intrinsic elastic properties and high-pressure structural evolution of hybrid perovskites, and the fundamental structure–mechanical property relationships are insufficiently understood. Here, we report the elastic behavior of a three-dimensional (3D) hybrid organic–inorganic perovskite, (DABCO)RbBr₃ (DABCO = triethylenediammonium), and confirm the processability through processing with chiral metasurfaces and the generation of circular dichroism. Our in situ high-pressure synchrotron X-ray diffraction experiments demonstrate that this crystal does not start to amorphize until 2.3 GPa. Density functional theory calculations reveal that its E, G and v range between 20.73 and 27.93 GPa, 8.21 and 11.62 GPa and 0.18–0.39, respectively. Additionally, due to the low elastic moduli and polar crystal structure, we fabricate a device of (DABCO)RbBr₃ composite film, which shows favorable performance for piezoelectric energy harvesting. This work utilizes (DABCO)RbBr₃ to open up new avenues for applications in manufacturing and energy harvesting. Full article

Zinc titanate (ZnTiO₃) is a chemically stable and non-toxic oxide perovskite whose photovoltaic potential remains largely unexplored due to its wide indirect bandgap. This study evaluates whether oxygen-vacancy (F-center) engineering can tailor its electronic structure and improve its suitability as a photovoltaic absorber. Density Functional Theory (DFT) calculations using VASP (PAW − GGA/PBE + U) were performed to evaluate structural stability, electronic properties, and electron affinity, while optical absorption was modeled through a combined Tauc–Gaussian approach. Device performance was assessed via SCAPS-1D simulations in an FTO/ZnO/ZnTiO₃/Spiro-OMeTAD architecture. Oxygen vacancies induce bandgap narrowing from ~2.96 eV to ~1.47 eV and generate Ti-3d-dominated donor-like and deep intragap states. The calculated electron affinity is ~3.77 eV. Simulated single-layer devices reach Voc ≈ 1.11 V, Jsc ≈ 8.27 mA·cm⁻², FF ≈ 83%, and a maximum efficiency of ~7.65%, primarily limited by moderate absorption strength and defect-assisted recombination. Multilayer configurations indicate that geometric optimization can significantly enhance projected efficiency, approaching 19.25% under idealized conditions. Although vacancy engineering extends visible-light absorption, the intrinsic indirect band-gap character constrains the ultimate photovoltaic performance of ZnTiO₃. Full article

The potential of La_0.2Sr_0.8MnO₃ (LSM28) perovskite oxide for thermochemical energy storage (TCES) is assessed by analyzing its thermochemical performance. The TCES capacity of LSM28 was measured using a non-stoichiometric and van’t Hoff analysis at various reduction temperatures ( T r e d ) and oxygen partial pressures ( P O 2 ). O₂ release and the associated non-stoichiometry (δ) increase with T r e d and decrease with P O 2 , according to the results, reaching a maximum δ of 0.101 at 1473 K and 0.0001 atm. The van’t Hoff research also showed that LSM28’s TCES capacity fluctuates greatly with δ, peaking at 37.1 kJ/kg under ideal circumstances. Full article

Junction spectroscopy techniques (JSTs) are powerful tools for investigating electrically active defects in semiconductors. Originally developed to study point-like defects in bulk semiconductors, JSTs have since been extended to increasingly complex systems, providing valuable insights into defect energetics and interactions. This review paper outlines the fundamental principles of JSTs and critically examines their application to emerging materials, such as perovskite solar cells and two-dimensional (2D) materials. By highlighting both the capabilities and limitations of JSTs in these non-classical systems, the review demonstrates their continued relevance and important role in advancing next-generation semiconductor materials and devices. Full article

Polymeric hole-transport materials (HTMs) play a pivotal role in improving the efficiency, stability, and scalability of perovskite solar cells (PSCs). Owing to their structural tunability, polymeric HTMs enable effective control over energy-level alignment, charge transport, interfacial interactions, and film formation. This review summarizes recent advances in polymeric HTMs, including conjugated-backbone polymers, donor–acceptor (D–A) copolymers, and emerging architectures such as hyperbranched, ionic, chelating, and anchorable polymer systems. Particular emphasis is placed on structure–property–performance relationships and interfacial engineering strategies that govern device efficiency and long-term operational stability in PSCs. Finally, the key challenges and future directions for developing scalable and robust polymeric HTMs are discussed. Full article

Two-dimensional (2D) materials are competitive in a diverse range of areas, spanning from electronic and optoelectronic devices to wearable devices, due to their unique physical and chemical characteristics, as well as remarkable flexibility. As a typical 2D material, lead iodide (PbI₂), featuring a high atomic number and tunable band gap, has been extensively studied in many applications of electroluminescent (EL) devices, photodetectors, and perovskite solar cells. However, high-performance PbI₂-based photodetectors remain a challenge. Herein, we present a high-performance flexible photodetector based on 2D layered PbI₂ nanoplates, which were synthesized via a straightforward air sublimation method. The PbI₂-based photodetector exhibits an excellent photoresponse and the highest responsivity peaks at 34 A/W at 405 nm, together with an ultrahigh transient switching on/off current ratio of 10⁷. Due to a low dark current (10⁻¹⁴ A), the device exhibits an extremely low noise level (<10⁻²⁶ A²Hz⁻¹) and acceptable detectivity (2 × 10¹⁰ Jones). Furthermore, remarkable mechanical flexibility was observed in the device on a PET substrate, preserving both its electrical conductance and photoresponse stability after 560 bending cycles. Finally, high-resolution imaging applications were implemented under a 100 Hz modulated light signal. This work highlights the superior optoelectrical properties of 2D PbI₂ growth by the in-air sublimation method and proves its promising future in flexible and wearable optoelectronic devices. Full article

In this work, La_0.70Ca_0.25Sr_0.05MnO₃ perovskite nanoparticles were produced in large amounts (in a single batch) and were embedded into filaments for 3D printing alongside carbon fibers. The produced materials showed room-temperature magnetocaloric effects proportional to the quantity of encapsulated nanoparticles. Moreover, the thermal properties of 3D-printed pellets (produced using the composite filaments) were also analyzed and compared to standard filaments. Full article

A high-entropy strategy has emerged as a promising approach to enhance the functional properties of piezoelectric ceramics for biomedical applications. For this reason, we have designed two novel high-entropy ceramics, (Bi_1/2Na_1/2)(Zr_1/3Sn_1/3Ti_1/3)O₃(BNZST) and (Bi_1/2Na_1/2)(Zr_1/4Sn_1/4Hf_1/4Ti_1/4)O₃(BNZSHT), which were synthesized via a two-step solid-state reaction. The phase structure, surface morphology, biocompatibility, and in vitro bioactivity were assessed. The results showed both ceramics adopted perovskite structures. BNZST and BNZSHT ceramics had relatively even crystallite sizes and element distribution, as well as achieving piezoelectric (d₃₃ ≥ 78 pC/N) properties. In vitro tests confirmed a high relative cell growth rate (RSG, >80%) after co-culturing BNZST or BNZSHT ceramic with murine fibroblasts L929 for more than 3 days. In particular, the surface with electric charge enhanced L929 with more extensive, widespread, and dense proliferation for the BNZST ceramic compared to ceramics without BNZST or unpolarized BNZST. The above indicated that multi-element doping and entropy stabilization established a novel pathway for developing a high-entropy bio-piezoelectric ceramics with high biocompatibility and bioactivity, providing the possibility for their use in bone repair materials. Full article

Lead-free perovskite solar cells have become attractive as they are more environmentally friendly than their lead-based counterparts. Among these lead-free perovskite materials is MASnI₂Br, which has attracted considerable attention due to its environmentally friendly advantages and beneficial optoelectronic properties. However, further enhancement is required in order to improve the power conversion efficiencies. In this study, an MASnI₂Br-based perovsdkite solar cell is designed and optimized using SCAPS-1D simulations. An extensive iterative simulation approach is carried out to optimize critical parameters such as electron affinity, energy bandgap, layer thickness and doping concentration for both transport layers. In addition, the thickness of the MASnI₂Br absorbing layer is optimized. With the improved device setup, the maximum achievable power conversion efficiency is 24%. Furthermore, by matching the optimized electronic structure with realistic transport materials, CBTS and TiO₂ are identified as suitable hole and electron transport layers, respectively. The proposed TiO₂/MASnI₂Br/CBTS perovskite solar cell has a power conversion efficiency of about 23.6%. Full article

Two-dimensional (2D) Ruddlesden–Popper (RP) tin halide perovskites have attracted considerable attention as lead-free photovoltaic absorbers; however, the impact of organic A-site cations on their structure and pressure-dependent optoelectronic behavior remains underexplored. In this study, density functional theory (DFT) is used to investigate the structural, electronic, and optical properties of A₂SnI₄ (A = GUA⁺, DMA⁺, MA⁺) under ambient conditions and under hydrostatic pressure. All three compounds adopt layered frameworks in which the organic cations occupy the interlayer region, while SnI₆ octahedra form the inorganic slabs. Band-gap calculations are performed using HSE06 for ambient pressure, known for its accuracy in electronic structure predictions, and PBE for pressure simulations, due to its computational efficiency in large-scale systems. At ambient pressure, Hybrid-functional (HSE06) calculations indicate that all three materials are direct-gap semiconductors, with band gaps of 2.25 eV for MA2SnI₄, 2.98 eV for DMA2SnI4, and 2.85 eV for GUA2SnI4. Under hydrostatic compression, DMA₂SnI₄ shows comparatively modest band-gap variation and saturates near 1.7 eV. In contrast, GUA₂SnI₄ and MA₂SnI₄ exhibit pronounced band-gap narrowing, including a pressure-induced direct-to-indirect transition near 2 GPa, with band gaps decreasing to 0.59 eV (GUA₂SnI₄) and 0.34 eV (MA₂SnI₄) at elevated pressures. Overall, these findings highlight that A-site chemistry, combined with hydrostatic pressure, enables tuning the electronic and optical responses in tin-based 2D RP perovskites, demonstrating their promise as tunable, lead-free photovoltaic absorbers. Full article

To synergistically integrate piezoelectric and varistor functionalities in a single material, PNN-PZT piezoelectric powder (abbreviated as P) and ZnO-based varistor powder (abbreviated as Z) were utilized to fabricate PZT-ZnO composite ceramics (denoted as PZm) via conventional solid-state sintering. The P/Z molar ratio was regulated to 1/0.9, 1/1.05, 1/1.2, 1/1.35, and 1/1.5 to systematically study its influence on the phase composition, microstructure, and electrical properties of the composites. XRD, SEM, EDS characterization, and electrical performance tests were carried out. Results indicate that all PZm samples exhibit the biphasic coexistence of perovskite (piezoelectric phase) and wurtzite (varistor phase) without impurity phases, consisting of large perovskite grains with distinct edges and small wurtzite grains with smooth surfaces. The PZ3 sample (P/Z = 1/1.2) achieves optimal comprehensive properties: d₃₃ = 161 pC/N, k_p = 0.25, Ɛ_r = 2527, tan δ = 3.83%, E_1mA = 1396 V/mm, I_L = 8.2 mA, α = 22.06. This work confirms the synergistic optimization of piezoelectric and varistor properties in PZT-ZnO composites, providing a reliable experimental basis for the formulation design and performance regulation of multifunctional ceramics. Full article