Pub Date : 2025-12-24DOI: 10.1016/j.mtphys.2025.102002
Wenhao Li , Yudi Wang , Chong Di , Jingwei Chen , Jingxin Chen , Biao Sun , Yang Ding , Zhiping Huang , Deyuan Wei , Ying Xu
Alkaline-earth metal fluorides are promising dopant-free interlayers for forming electron-selective contacts on crystalline silicon (c-Si). In this work, a 4 nm-thick ultrathin SrFx film is deposited on n-type Czochralski (CZ) Si, and stacked with a 2 nm Mg metal layer to construct an electron transport layer (ETL), achieving favorable surface passivation and band alignment. The interfacial structure and chemical states are characterized by X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), and cross-sectional transmission electron microscopy/energy-dispersive X-ray spectroscopy (TEM/EDS), the results confirm a clean SrFx/metal interface with a low work function of 2.82 eV, while the wide-bandgap characteristic of the fluoride is well-preserved after metal deposition. Electrical measurements via the transmission line method (TLM) demonstrate that the SrFx-based contact achieves a low specific contact resistivity (ρc) as low as 17.7 mΩ cm2. When integrated into n-type Si solar cells, the SrFx/Mg rear tact suppresses carrier recombination and enhances electron extraction efficiency, yielding a short-circuit current density (Jsc) of 40.2 mA cm−2 and a power conversion efficiency (PCE) of 20.8 %. This performance outperforms that of the pure metal reference cell, demonstrating the great potential of SrFx as a robust electron-selective interlayer for high-performance dopant-free silicon solar cells.
{"title":"SrFx/Mg stack as electron transport layer for dopant-free silicon heterojunction solar cells","authors":"Wenhao Li , Yudi Wang , Chong Di , Jingwei Chen , Jingxin Chen , Biao Sun , Yang Ding , Zhiping Huang , Deyuan Wei , Ying Xu","doi":"10.1016/j.mtphys.2025.102002","DOIUrl":"10.1016/j.mtphys.2025.102002","url":null,"abstract":"<div><div>Alkaline-earth metal fluorides are promising dopant-free interlayers for forming electron-selective contacts on crystalline silicon (c-Si). In this work, a 4 nm-thick ultrathin SrF<sub>x</sub> film is deposited on n-type Czochralski (CZ) Si, and stacked with a 2 nm Mg metal layer to construct an electron transport layer (ETL), achieving favorable surface passivation and band alignment. The interfacial structure and chemical states are characterized by X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), and cross-sectional transmission electron microscopy/energy-dispersive X-ray spectroscopy (TEM/EDS), the results confirm a clean SrF<sub>x</sub>/metal interface with a low work function of 2.82 eV, while the wide-bandgap characteristic of the fluoride is well-preserved after metal deposition. Electrical measurements via the transmission line method (TLM) demonstrate that the SrF<sub>x</sub>-based contact achieves a low specific contact resistivity (ρ<sub>c</sub>) as low as 17.7 mΩ cm<sup>2</sup>. When integrated into n-type Si solar cells, the SrF<sub>x</sub>/Mg rear tact suppresses carrier recombination and enhances electron extraction efficiency, yielding a short-circuit current density (J<sub>sc</sub>) of 40.2 mA cm<sup>−2</sup> and a power conversion efficiency (PCE) of 20.8 %. This performance outperforms that of the pure metal reference cell, demonstrating the great potential of SrF<sub>x</sub> as a robust electron-selective interlayer for high-performance dopant-free silicon solar cells.</div></div>","PeriodicalId":18253,"journal":{"name":"Materials Today Physics","volume":"60 ","pages":"Article 102002"},"PeriodicalIF":9.7,"publicationDate":"2025-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145813650","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-24DOI: 10.1016/j.mtphys.2025.101998
David Naranjo , Sonia Lanzalaco , Ahammed H.M. Mohammed-Sadhakathullah , Núria Borras , José García-Torres , Juan Torras
Thermoresponsive hydrogels based on poly(N-isopropylacrylamide) (PNiPAAm) and its derivatives are promising for advanced applications, including solar-driven water purification, due to their tunable volume phase transition (VPT) behavior. In this study, we investigate the effect of poly(3,4-ethylenedioxythiophene) (PEDOT) nanoparticles (NPs) on the VPT of three PNiPAAm derivatives: poly(N-n-propylacrylamide) (PNnPAAm), PNiPAAm, and poly(N-isopropylmethacrylamide) (PNiPMAAm), with distinct hydrophobic side chains. Macrohydrogels were synthesized with and without PEDOT, and their thermal responsiveness was characterized using temperature-dependent Raman spectroscopy, which enabled differentiation between intermediate and free water. Incorporation of PEDOT systematically increased swelling ratios and pore sizes, with the most pronounced effects observed below the lower critical solution temperature, and promoted the formation of intermediate water strongly associated with the polymer network. Molecular dynamics simulations corroborated these observations, showing enhanced water–polymer interactions in the presence of PEDOT, while quantum mechanical calculations revealed stabilization of hydrogel–PEDOT complexes through weak polar interactions and increased electronic polarization, which reinforce hydrogen bonding and modulate the local electrostatic environment. These combined experimental and computational results provide a molecular-level understanding of how conductive polymers influence hydration structure and VPT thermodynamics, offering a framework for rationally designing smart hydrogels with tailored swelling, porosity, and water-binding properties for energy-efficient materials applications.
{"title":"Conductive nanocomposites as molecular modulators of hydration in thermoresponsive PNiPAAm-derivative hydrogels","authors":"David Naranjo , Sonia Lanzalaco , Ahammed H.M. Mohammed-Sadhakathullah , Núria Borras , José García-Torres , Juan Torras","doi":"10.1016/j.mtphys.2025.101998","DOIUrl":"10.1016/j.mtphys.2025.101998","url":null,"abstract":"<div><div>Thermoresponsive hydrogels based on poly(N-isopropylacrylamide) (PNiPAAm) and its derivatives are promising for advanced applications, including solar-driven water purification, due to their tunable volume phase transition (VPT) behavior. In this study, we investigate the effect of poly(3,4-ethylenedioxythiophene) (PEDOT) nanoparticles (NPs) on the VPT of three PNiPAAm derivatives: poly(<em>N</em>-<em>n</em>-propylacrylamide) (PNnPAAm), PNiPAAm, and poly(<em>N</em>-isopropylmethacrylamide) (PNiPMAAm), with distinct hydrophobic side chains. Macrohydrogels were synthesized with and without PEDOT, and their thermal responsiveness was characterized using temperature-dependent Raman spectroscopy, which enabled differentiation between intermediate and free water. Incorporation of PEDOT systematically increased swelling ratios and pore sizes, with the most pronounced effects observed below the lower critical solution temperature, and promoted the formation of intermediate water strongly associated with the polymer network. Molecular dynamics simulations corroborated these observations, showing enhanced water–polymer interactions in the presence of PEDOT, while quantum mechanical calculations revealed stabilization of hydrogel–PEDOT complexes through weak polar interactions and increased electronic polarization, which reinforce hydrogen bonding and modulate the local electrostatic environment. These combined experimental and computational results provide a molecular-level understanding of how conductive polymers influence hydration structure and VPT thermodynamics, offering a framework for rationally designing smart hydrogels with tailored swelling, porosity, and water-binding properties for energy-efficient materials applications.</div></div>","PeriodicalId":18253,"journal":{"name":"Materials Today Physics","volume":"60 ","pages":"Article 101998"},"PeriodicalIF":9.7,"publicationDate":"2025-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145822863","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-22DOI: 10.1016/j.mtphys.2025.101994
Xinglin Xiao , Rongkun Chen , Xiangyu Xu , Xiaolong Li , Guoliang Ma , Yali Mao , Yuan Li , Xing Hu , Haoyang Peng , Jianing Liang , Shujuan Liu , Kelvin H.L. Zhang , Shiqian Hu , Chao Yuan
β-(AlxGa1-x)2O3 (AGO) alloys offer transformative potential for high-power electronics, yet their thermal properties necessitate further research to enable electro-thermal co-design. Persistent challenges in accurately modeling atomic-scale disorder and in synthesizing compositionally graded AGO ternary alloy thin films fundamentally limit the mechanistic elucidation of alloy phonon transport through synergistic theory-experiment frameworks. By integrating neural evolution potential molecular dynamics with transient thermoreflectance experiments, we resolve the spectral phonon behaviors across million-atom disordered systems. Results reveal a two-regime thermal conductivity (TC) reduction: a sharp 43 % drop at x = 0–0.1 (7–4 W m−1 K−1) driven by suppressed low-frequency phonons (0–10 THz, 76 % loss), followed by a gradual 18 % decline at x = 0.1–0.5 (4–3.3 W m−1 K−1) via mid-frequency (10–15 THz) spectral compensation. Crystal orbital Hamilton population analysis reveals that the Al-O bond is strengthened and a reduction in atomic mass elevates the mid/high-frequency phonon density of states (PDOS), slowing TC degradation. The Virtual Crystal Approximation (VCA) simulation-based fitting to molecular dynamics results quantitatively resolves the dominance of strain-field scattering (>60 %) over mass-defect effects, a phenomenon driven by Al-induced bond-length mismatch and lattice symmetry breaking. This mechanism is experimentally corroborated by Raman spectral extinction of Ga2O3-characteristic phonon modes for x ≥ 0.1. Similarly, the thermal boundary conductance (TBC) of AGO/Al2O3 exhibits concentration-independent stability (<10 % variation for x > 0.1), resulting from PDOS redistribution-driven spectral coupling. This work provides atomic-scale insights into phonon engineering strategies for AGO-based power electronics, highlighting the critical role of frequency-resolved phonon manipulation in electro-thermal co-design.
{"title":"Probing atomic-scale origins of frequency-dependent phonon transport in aluminum gallium oxide ternary alloy films","authors":"Xinglin Xiao , Rongkun Chen , Xiangyu Xu , Xiaolong Li , Guoliang Ma , Yali Mao , Yuan Li , Xing Hu , Haoyang Peng , Jianing Liang , Shujuan Liu , Kelvin H.L. Zhang , Shiqian Hu , Chao Yuan","doi":"10.1016/j.mtphys.2025.101994","DOIUrl":"10.1016/j.mtphys.2025.101994","url":null,"abstract":"<div><div>β-(Al<sub><em>x</em></sub>Ga<sub>1-<em>x</em></sub>)<sub>2</sub>O<sub>3</sub> (AGO) alloys offer transformative potential for high-power electronics, yet their thermal properties necessitate further research to enable electro-thermal co-design. Persistent challenges in accurately modeling atomic-scale disorder and in synthesizing compositionally graded AGO ternary alloy thin films fundamentally limit the mechanistic elucidation of alloy phonon transport through synergistic theory-experiment frameworks. By integrating neural evolution potential molecular dynamics with transient thermoreflectance experiments, we resolve the spectral phonon behaviors across million-atom disordered systems. Results reveal a two-regime thermal conductivity (TC) reduction: a sharp 43 % drop at <em>x</em> = 0–0.1 (7–4 W m<sup>−1</sup> K<sup>−1</sup>) driven by suppressed low-frequency phonons (0–10 THz, 76 % loss), followed by a gradual 18 % decline at <em>x</em> = 0.1–0.5 (4–3.3 W m<sup>−1</sup> K<sup>−1</sup>) via mid-frequency (10–15 THz) spectral compensation. Crystal orbital Hamilton population analysis reveals that the Al-O bond is strengthened and a reduction in atomic mass elevates the mid/high-frequency phonon density of states (PDOS), slowing TC degradation. The Virtual Crystal Approximation (VCA) simulation-based fitting to molecular dynamics results quantitatively resolves the dominance of strain-field scattering (>60 %) over mass-defect effects, a phenomenon driven by Al-induced bond-length mismatch and lattice symmetry breaking. This mechanism is experimentally corroborated by Raman spectral extinction of Ga<sub>2</sub>O<sub>3</sub>-characteristic phonon modes for <em>x</em> ≥ 0.1. Similarly, the thermal boundary conductance (TBC) of AGO/Al<sub>2</sub>O<sub>3</sub> exhibits concentration-independent stability (<10 % variation for <em>x</em> > 0.1), resulting from PDOS redistribution-driven spectral coupling. This work provides atomic-scale insights into phonon engineering strategies for AGO-based power electronics, highlighting the critical role of frequency-resolved phonon manipulation in electro-thermal co-design.</div></div>","PeriodicalId":18253,"journal":{"name":"Materials Today Physics","volume":"60 ","pages":"Article 101994"},"PeriodicalIF":9.7,"publicationDate":"2025-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145801389","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-22DOI: 10.1016/j.mtphys.2025.101996
Yue Liu , Minming Zou , Yan Ma , Wenjing Chen , Qinglin Li , Xiongxin Jiang , Xiaowu Hu
The carbonization temperature of metal-organic frameworks (MOFs) is a critical factor in tailoring the structure and properties of derived porous carbons. This study systematically investigates the effect of carbonization temperature on the photo-magnetic-thermal performance of composite phase change materials (CPCMs) derived from zeolitic imidazolate framework-67 (ZIF-67). Magnetic cobalt nanoparticle-embedded porous carbons (CZIF-X, where X represents the carbonization temperature, 700, 800, and 900 °C) were synthesized and incorporated into stearic acid (SA) to form SA/CZIF-X CPCMs. The results demonstrate that the elevated temperature enhances broadband solar absorption and magnetic responsiveness, leading to superior energy conversion and storage efficiency. The synergistic effect between the localized surface plasmon resonance (LSPR) of cobalt nanoparticles and the graphitic carbon network causes this enhancement. Furthermore, molecular dynamics (MD) simulations reveal that the optimized carbonization process reduces the interfacial thermal resistance between SA and the carbon matrix (CZIF-900) by 41.25 % (to 0.94 × 10−8 K m2 W−1) compared to the precursor (ZIF-67, 1.6 × 10−8 K m2 W−1), significantly facilitating phonon transport at the interface. This work, integrating experiment with simulation, provides fundamental insights into the temperature-dependent evolution of MOF-derived composites and establishes a design principle for developing efficient multi-modal, multi-physical field energy conversion and storage systems.
金属有机骨架（MOFs）的碳化温度是影响衍生多孔碳结构和性能的关键因素。本研究系统地研究了碳化温度对沸石咪唑酸骨架-67 （ZIF-67）复合相变材料（CPCMs）光磁热性能的影响。合成磁性钴纳米颗粒包埋多孔碳（CZIF-X，其中X代表碳化温度，700、800和900℃），并将其掺入硬脂酸（SA）中形成SA/CZIF-X cpcm。结果表明，升高的温度增强了宽带太阳能吸收和磁响应性，从而提高了能量转换和存储效率。钴纳米粒子的局部表面等离子体共振（LSPR）与石墨碳网络之间的协同效应导致了这种增强。此外，分子动力学（MD）模拟表明，与前驱体（ZIF-67, 1.6 × 10−8 K m2 W−1）相比，优化的碳化过程使SA与碳基体（cif -900）之间的界面热阻降低了41.25% (0.94 × 10−8 K m2 W−1)，显著促进了界面上的声子输运。本研究将实验与模拟相结合，为mof衍生复合材料的温度依赖演化提供了基本见解，并为开发高效的多模态、多物理场能量转换和存储系统建立了设计原则。
{"title":"Effect of carbonization temperature on the photo-magnetic-thermal properties of cobalt-based metal organic framework-derived composite phase change materials: Experimental and molecular dynamics simulations","authors":"Yue Liu , Minming Zou , Yan Ma , Wenjing Chen , Qinglin Li , Xiongxin Jiang , Xiaowu Hu","doi":"10.1016/j.mtphys.2025.101996","DOIUrl":"10.1016/j.mtphys.2025.101996","url":null,"abstract":"<div><div>The carbonization temperature of metal-organic frameworks (MOFs) is a critical factor in tailoring the structure and properties of derived porous carbons. This study systematically investigates the effect of carbonization temperature on the photo-magnetic-thermal performance of composite phase change materials (CPCMs) derived from zeolitic imidazolate framework-67 (ZIF-67). Magnetic cobalt nanoparticle-embedded porous carbons (CZIF-X, where <em>X</em> represents the carbonization temperature, 700, 800, and 900 °C) were synthesized and incorporated into stearic acid (SA) to form SA/CZIF-X CPCMs. The results demonstrate that the elevated temperature enhances broadband solar absorption and magnetic responsiveness, leading to superior energy conversion and storage efficiency. The synergistic effect between the localized surface plasmon resonance (LSPR) of cobalt nanoparticles and the graphitic carbon network causes this enhancement. Furthermore, molecular dynamics (MD) simulations reveal that the optimized carbonization process reduces the interfacial thermal resistance between SA and the carbon matrix (CZIF-900) by 41.25 % (to 0.94 × 10<sup>−8</sup> K m<sup>2</sup> W<sup>−1</sup>) compared to the precursor (ZIF-67, 1.6 × 10<sup>−8</sup> K m<sup>2</sup> W<sup>−1</sup>), significantly facilitating phonon transport at the interface. This work, integrating experiment with simulation, provides fundamental insights into the temperature-dependent evolution of MOF-derived composites and establishes a design principle for developing efficient multi-modal, multi-physical field energy conversion and storage systems.</div></div>","PeriodicalId":18253,"journal":{"name":"Materials Today Physics","volume":"60 ","pages":"Article 101996"},"PeriodicalIF":9.7,"publicationDate":"2025-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145813926","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-19DOI: 10.1016/j.mtphys.2025.101993
Shaojie Zheng , Beili Pang , Yili Liu , Junyang Ma , Jianguang Feng , Hongzhou Dong , Liyan Yu , Lifeng Dong
In this study, a novel bifunctional additive strategy was developed to enhance the performance of fully inorganic CsPbBr3 perovskite solar cells. Propylene glycol methyl ether (PM) was employed as a single additive, and a hybrid additive was formed by combining PM with methyl benzoate (MB). The power conversion efficiency increased from 5.77 % to 8.63 % with PM alone, and further to 9.57 % with the PM–MB hybrid. These additives reduce uncoordinated Pb2+ ions and passivate defects. Surface electrostatic potential calculations reveal that PM and MB contain functional groups with negative electrostatic potential, enabling them to anchor to the perovskite surface without inducing damage. Binding energy calculations and X-ray photoelectron spectroscopy showed a shift of Pb peaks to lower binding energies, indicating reduced uncoordinated Pb2+ ions and enhanced defect passivation, which promote grain growth. Additionally, the ether and ester groups in PM and MB facilitate the extraction of residual N, N- dimethylformamide (DMF). Fourier-transform infrared spectroscopy confirmed the disappearance of DMF-related peaks after treatment, indicating effective solvent removal. Grazing-incidence X-ray diffraction further demonstrated enhanced grain size and orientation, reflecting reduced solvent-induced damage and improved film quality. As a result, unencapsulated devices retained over 90 % of their initial performance after 2500 h in air.
{"title":"Synergistic dual-additive engineering for high-performance and air-stable CsPbBr3 perovskite solar cells","authors":"Shaojie Zheng , Beili Pang , Yili Liu , Junyang Ma , Jianguang Feng , Hongzhou Dong , Liyan Yu , Lifeng Dong","doi":"10.1016/j.mtphys.2025.101993","DOIUrl":"10.1016/j.mtphys.2025.101993","url":null,"abstract":"<div><div>In this study, a novel bifunctional additive strategy was developed to enhance the performance of fully inorganic CsPbBr<sub>3</sub> perovskite solar cells. Propylene glycol methyl ether (PM) was employed as a single additive, and a hybrid additive was formed by combining PM with methyl benzoate (MB). The power conversion efficiency increased from 5.77 % to 8.63 % with PM alone, and further to 9.57 % with the PM–MB hybrid. These additives reduce uncoordinated Pb<sup>2+</sup> ions and passivate defects. Surface electrostatic potential calculations reveal that PM and MB contain functional groups with negative electrostatic potential, enabling them to anchor to the perovskite surface without inducing damage. Binding energy calculations and X-ray photoelectron spectroscopy showed a shift of Pb peaks to lower binding energies, indicating reduced uncoordinated Pb<sup>2+</sup> ions and enhanced defect passivation, which promote grain growth. Additionally, the ether and ester groups in PM and MB facilitate the extraction of residual N, N- dimethylformamide (DMF). Fourier-transform infrared spectroscopy confirmed the disappearance of DMF-related peaks after treatment, indicating effective solvent removal. Grazing-incidence X-ray diffraction further demonstrated enhanced grain size and orientation, reflecting reduced solvent-induced damage and improved film quality. As a result, unencapsulated devices retained over 90 % of their initial performance after 2500 h in air.</div></div>","PeriodicalId":18253,"journal":{"name":"Materials Today Physics","volume":"60 ","pages":"Article 101993"},"PeriodicalIF":9.7,"publicationDate":"2025-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145784641","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-16DOI: 10.1016/j.mtphys.2025.101991
Chi Zhang , Fengdeng Liu , Donghwan Kim , Xiaotian Xu , Silu Guo , Yankai Pei , K. Andre Mkhoyan , Tianli Feng , Bharat Jalan , Xiaojia Wang
We report the thickness-dependent thermal conductivity of ultra-wide bandgap (UWBG) strontium stannate (SrSnO3, SSO) thin films and reconstruct the phonon mean-free-path (MFP) distribution directly from experimental data. A series of SSO films with thicknesses ranging from 10 to 100 nm was grown using hybrid molecular beam epitaxy. The through-plane thermal conductivities (ΛSSO) were measured with time-domain thermoreflectance (TDTR), together with prior TDTR measurements of a 350-nm film. A pronounced thickness dependence is observed, where reducing the thickness from 350 nm to 100 nm and 10 nm suppresses ΛSSO by ∼30% and 70%, respectively. Our analyses decompose ΛSSO into particle-like (population) and wave-like (coherence) contributions based on the idea of Wigner transport formulation. Assuming a thickness-independent coherence contribution, we isolate the population contribution and reconstruct its phonon MFP distribution by adopting an integral MFP formalism. This approach enables direct determination of the MFP spectrum from experimental data of thickness-dependent ΛSSO without relying on phonon dispersion calculations or scattering models. Excellent agreement in ΛSSO between model calculation and experimental data is achieved, indicating that phonons with MFPs below 100 nm contribute over 80% of bulk thermal conductivity, with the full MFP spectrum converged at ∼170 nm. This approach provides an experimental pathway to study particle-like and wave-like thermal transport and serves as an example of reconstructing phonon MFP spectra in materials with strong lattice anharmonicity. These findings yield critical insights into structure-thermal property relationships and offer guidance for the design and optimization of UWBG perovskite-based electronic devices under nanoscale thermal constraints.
{"title":"Probing phonon mean-free-path distribution via thickness-dependent thermal conductivity in epitaxial SrSnO3","authors":"Chi Zhang , Fengdeng Liu , Donghwan Kim , Xiaotian Xu , Silu Guo , Yankai Pei , K. Andre Mkhoyan , Tianli Feng , Bharat Jalan , Xiaojia Wang","doi":"10.1016/j.mtphys.2025.101991","DOIUrl":"10.1016/j.mtphys.2025.101991","url":null,"abstract":"<div><div>We report the thickness-dependent thermal conductivity of ultra-wide bandgap (UWBG) strontium stannate (SrSnO<sub>3</sub>, SSO) thin films and reconstruct the phonon mean-free-path (MFP) distribution directly from experimental data. A series of SSO films with thicknesses ranging from 10 to 100 nm was grown using hybrid molecular beam epitaxy. The through-plane thermal conductivities (Λ<sub>SSO</sub>) were measured with time-domain thermoreflectance (TDTR), together with prior TDTR measurements of a 350-nm film. A pronounced thickness dependence is observed, where reducing the thickness from 350 nm to 100 nm and 10 nm suppresses Λ<sub>SSO</sub> by ∼30% and 70%, respectively. Our analyses decompose Λ<sub>SSO</sub> into particle-like (population) and wave-like (coherence) contributions based on the idea of Wigner transport formulation. Assuming a thickness-independent coherence contribution, we isolate the population contribution and reconstruct its phonon MFP distribution by adopting an integral MFP formalism. This approach enables direct determination of the MFP spectrum from experimental data of thickness-dependent Λ<sub>SSO</sub> without relying on phonon dispersion calculations or scattering models. Excellent agreement in Λ<sub>SSO</sub> between model calculation and experimental data is achieved, indicating that phonons with MFPs below 100 nm contribute over 80% of bulk thermal conductivity, with the full MFP spectrum converged at ∼170 nm. This approach provides an experimental pathway to study particle-like and wave-like thermal transport and serves as an example of reconstructing phonon MFP spectra in materials with strong lattice anharmonicity. These findings yield critical insights into structure-thermal property relationships and offer guidance for the design and optimization of UWBG perovskite-based electronic devices under nanoscale thermal constraints.</div></div>","PeriodicalId":18253,"journal":{"name":"Materials Today Physics","volume":"60 ","pages":"Article 101991"},"PeriodicalIF":9.7,"publicationDate":"2025-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145760378","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-16DOI: 10.1016/j.mtphys.2025.101992
Yingfei Tang , Xili Wen , Huijuan Wu , Keke Liu , Yanwen Shan , Pierre Ferdinand Poudeu Poudeu , Vladimir Khovaylo , Zhiquan Chen , Qingjie Zhang , Xianli Su , Xinfeng Tang
Conventional doping approaches for enhancing thermoelectric performance typically rely on multi-element co-doping, which complicates both the fabrication process and the interpretation of underlying mechanisms. In this study, we demonstrate that a single dopant, Sb, can effectively modulate the thermoelectric properties of PbSe through a concentration-dependent regulatory mechanism. Sb dopant at low concentrations (x ≤ 1.5 %) suppresses Pb vacancies in the structure which not only enhances doping efficiency but also maintains high carrier mobility at elevated carrier concentrations. All these significantly boost the electrical transport properties. In contrast, excess Sb induces additional Pb vacancies at higher concentration (x > 1.5 %), which reduce both carrier concentration and mobility. By suppressing the formation of Pb vacancy with low dose of Sb content, a significantly improved ZTmax value of ∼1.43 is attained at 785 K for Pb0.997Sb0.003Se sample, representing an approximately 2-fold improvement over the pristine PbSe (ZTmax ∼ 0.55).
{"title":"Realization of defects evolution for boosting thermoelectric properties in Sb doped PbSe","authors":"Yingfei Tang , Xili Wen , Huijuan Wu , Keke Liu , Yanwen Shan , Pierre Ferdinand Poudeu Poudeu , Vladimir Khovaylo , Zhiquan Chen , Qingjie Zhang , Xianli Su , Xinfeng Tang","doi":"10.1016/j.mtphys.2025.101992","DOIUrl":"10.1016/j.mtphys.2025.101992","url":null,"abstract":"<div><div>Conventional doping approaches for enhancing thermoelectric performance typically rely on multi-element co-doping, which complicates both the fabrication process and the interpretation of underlying mechanisms. In this study, we demonstrate that a single dopant, Sb, can effectively modulate the thermoelectric properties of PbSe through a concentration-dependent regulatory mechanism. Sb dopant at low concentrations (x ≤ 1.5 %) suppresses Pb vacancies in the structure which not only enhances doping efficiency but also maintains high carrier mobility at elevated carrier concentrations. All these significantly boost the electrical transport properties. In contrast, excess Sb induces additional Pb vacancies at higher concentration (x > 1.5 %), which reduce both carrier concentration and mobility. By suppressing the formation of Pb vacancy with low dose of Sb content, a significantly improved <em>ZT</em><em><sub>max</sub></em> value of ∼1.43 is attained at 785 K for Pb<sub>0.997</sub>Sb<sub>0.003</sub>Se sample, representing an approximately 2-fold improvement over the pristine PbSe (<em>ZT</em><em><sub>max</sub></em> ∼ 0.55).</div></div>","PeriodicalId":18253,"journal":{"name":"Materials Today Physics","volume":"60 ","pages":"Article 101992"},"PeriodicalIF":9.7,"publicationDate":"2025-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145760379","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-14DOI: 10.1016/j.mtphys.2025.101988
Chao Wei, Kunwei Zheng
Bioelectronic sensors constructed from advanced polymeric and bio-synthetic materials emulate the mechanical softness and sensory functionality of human skin, enabling intimate and adaptive integration with biological tissues. Advances in the molecular tailoring of dielectric, conductive, and functional polymer composites, together with hybrid systems incorporating inorganic nonmetal components, have facilitated seamless integration with skin and living tissues. Despite substantial progress, the realization of stable, seamlessly connected, and biocompatible implantable bioelectronic sensors remains a major technological hurdle. This Review highlights emerging advances in soft bioelectronic sensors for both epidermal and implantable use, as well as recent developments in flexible electronic system platforms that enable in-depth exploration of physiological mechanisms and provide strategies to overcome fundamental barriers in biomedical applications. We first summarize advances in the development of skin-like soft sensors, with particular emphasis on innovations in epidermal soft bioelectronic sensing. Beneath the deformable epidermal layer, we highlight recent developments in implantable soft bioelectronic sensors that emulate the structural and mechanical characteristics of living tissues. Finally, we outline flexible electronic system platforms that enable seamless integration of soft and implantable bioelectronic sensors with biocompatible conductive platforms.
{"title":"Skin-inspired soft bioelectronic epidermal sensing, implantable applications and system integrations","authors":"Chao Wei, Kunwei Zheng","doi":"10.1016/j.mtphys.2025.101988","DOIUrl":"10.1016/j.mtphys.2025.101988","url":null,"abstract":"<div><div>Bioelectronic sensors constructed from advanced polymeric and bio-synthetic materials emulate the mechanical softness and sensory functionality of human skin, enabling intimate and adaptive integration with biological tissues. Advances in the molecular tailoring of dielectric, conductive, and functional polymer composites, together with hybrid systems incorporating inorganic nonmetal components, have facilitated seamless integration with skin and living tissues. Despite substantial progress, the realization of stable, seamlessly connected, and biocompatible implantable bioelectronic sensors remains a major technological hurdle. This Review highlights emerging advances in soft bioelectronic sensors for both epidermal and implantable use, as well as recent developments in flexible electronic system platforms that enable in-depth exploration of physiological mechanisms and provide strategies to overcome fundamental barriers in biomedical applications. We first summarize advances in the development of skin-like soft sensors, with particular emphasis on innovations in epidermal soft bioelectronic sensing. Beneath the deformable epidermal layer, we highlight recent developments in implantable soft bioelectronic sensors that emulate the structural and mechanical characteristics of living tissues. Finally, we outline flexible electronic system platforms that enable seamless integration of soft and implantable bioelectronic sensors with biocompatible conductive platforms.</div></div>","PeriodicalId":18253,"journal":{"name":"Materials Today Physics","volume":"60 ","pages":"Article 101988"},"PeriodicalIF":9.7,"publicationDate":"2025-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145753085","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-13DOI: 10.1016/j.mtphys.2025.101989
Loubaba Attou , Khadija El Maalam , Salah-Eddine Bouzarmine , Sohail Ait Jmal , Zineb El Kacemi , Meriem Ben Ali , Sanae Naamane , Omar Mounkachi , Patrick Fournier , Mohamed Balli
The search for efficient, low-temperature, and environmentally friendly cooling technologies has intensified interest in magnetocaloric materials. In this study, we report the aqueous synthesis of neodymium orthophosphate nanorods (NdPO4-NRs) via simple precipitation route using the synthetically accessible phosphoric acid as the primary reagent. Structural analysis clearly reveals a phase transition from a hydrated hexagonal rhabdophane-type structure (NdPO4·H2O, space group P3121) to a monoclinic anhydrous monazite-type structure (NdPO4, space group P21/n) upon thermal treatment. High-resolution (HRTEM), confirms the successful formation of well-defined, polycrystalline nanorods with uniform diameters of approximately 20 nm and lengths extending to several hundred nanometers. The lattice fringes are clearly resolved, reflecting the high crystallinity of both phases, indicating the successful growth of these compounds during the aqueous precipitation process. The inverse magnetic susceptibility measurements demonstrate clear antiferromagnetic interactions in both phases, supported by Curie-Weiss analysis and consistent with the calculated Nd-O-Nd and Nd-O-P-O-Nd path angles. Magnetic entropy changes yielded a value of 14.97 J/kg K for the hydrated form and 19.09 J/kg K for the anhydrous phase under a magnetic field change of 5 T, underscoring the influence of crystallographic transformation on magnetocaloric behavior. Furthermore, cost-effective synthesis, tunable structure, and competitive magnetocaloric performance, the abundance and lower cost of neodymium compared to heavier rare-earth elements, position NdPO4 as a potential candidate for efficient and economically sustainable cryogenic magnetic refrigeration.
{"title":"Phase-dependent structural and magnetic properties of NdPO4 nanorods for cryo-magnetocaloric cooling","authors":"Loubaba Attou , Khadija El Maalam , Salah-Eddine Bouzarmine , Sohail Ait Jmal , Zineb El Kacemi , Meriem Ben Ali , Sanae Naamane , Omar Mounkachi , Patrick Fournier , Mohamed Balli","doi":"10.1016/j.mtphys.2025.101989","DOIUrl":"10.1016/j.mtphys.2025.101989","url":null,"abstract":"<div><div>The search for efficient, low-temperature, and environmentally friendly cooling technologies has intensified interest in magnetocaloric materials. In this study, we report the aqueous synthesis of neodymium orthophosphate nanorods (NdPO<sub>4</sub>-NRs) via simple precipitation route using the synthetically accessible phosphoric acid as the primary reagent. Structural analysis clearly reveals a phase transition from a hydrated hexagonal rhabdophane-type structure (NdPO<sub>4</sub>·H<sub>2</sub>O, space group P3<sub>1</sub>21) to a monoclinic anhydrous monazite-type structure (NdPO<sub>4</sub>, space group P2<sub>1</sub>/n) upon thermal treatment. High-resolution (HRTEM), confirms the successful formation of well-defined, polycrystalline nanorods with uniform diameters of approximately 20 nm and lengths extending to several hundred nanometers. The lattice fringes are clearly resolved, reflecting the high crystallinity of both phases, indicating the successful growth of these compounds during the aqueous precipitation process. <em>The inverse m</em>agnetic susceptibility measurements demonstrate clear antiferromagnetic interactions in both phases, supported by Curie-Weiss analysis and consistent with the calculated Nd-O-Nd and Nd-O-P-O-Nd path angles. Magnetic entropy changes <span><math><mrow><msubsup><mrow><mo>−</mo><mo>Δ</mo><mi>S</mi></mrow><mi>M</mi><mi>max</mi></msubsup></mrow></math></span> yielded a value of 14.97 J/kg K for the hydrated form and 19.09 J/kg K for the anhydrous phase under a magnetic field change of 5 T, underscoring the influence of crystallographic transformation on magnetocaloric behavior. Furthermore, cost-effective synthesis, tunable structure, and competitive magnetocaloric performance, the abundance and lower cost of neodymium compared to heavier rare-earth elements, position NdPO<sub>4</sub> as a potential candidate for efficient and economically sustainable cryogenic magnetic refrigeration.</div></div>","PeriodicalId":18253,"journal":{"name":"Materials Today Physics","volume":"60 ","pages":"Article 101989"},"PeriodicalIF":9.7,"publicationDate":"2025-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145732263","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-13DOI: 10.1016/j.mtphys.2025.101987
Mingzhen Zhang , Puqing Jiang , Ronggui Yang
Accurate evaluation of buried thermal interfaces is vital for understanding and optimizing heat dissipation in wide- and ultra-wide-bandgap (WBG/UWBG) semiconductor devices. Conventional time-domain thermoreflectance (TDTR) typically probes only near-surface transport due to its restricted modulation frequency range. Here, we employ a frequency-tunable periodic waveform analysis TDTR (PWA-TDTR) technique to perform depth-resolved thermal measurements on three representative systems: epitaxial ε-Ga2O3/SiC, GaN/Si, and mechanically bonded GaN/diamond. By combining broadband multi-frequency probing with sensitivity-guided joint fitting, we quantitively determine interfacial thermal conductance, layer-specific thermal conductivity, and volumetric heat capacity, without requiring destructive sample preparation. The results reveal that the buried Ga2O3/SiC interface exhibits weak phonon transmission due to acoustic mismatch; the transition layers in GaN/Si act as phonon-impedance gradients that redistribute heat flux; and the GaN/diamond boundary remains the dominant thermal bottleneck despite diamond's ultrahigh bulk conductivity. These findings demonstrate that the modulation frequency in PWA-TDTR functions as a tunable probe of depth-dependent phonon transport, directly linking frequency-domain thermal response to interfacial energy transmission. Overall, this work positions PWA-TDTR as a versatile platform for investigating buried nonmetal–nonmetal interfaces in next-generation high-power and optoelectronic materials.
{"title":"Thermal characterization of buried interfaces in multilayer heterostructures via TDTR with periodic waveform analysis","authors":"Mingzhen Zhang , Puqing Jiang , Ronggui Yang","doi":"10.1016/j.mtphys.2025.101987","DOIUrl":"10.1016/j.mtphys.2025.101987","url":null,"abstract":"<div><div>Accurate evaluation of buried thermal interfaces is vital for understanding and optimizing heat dissipation in wide- and ultra-wide-bandgap (WBG/UWBG) semiconductor devices. Conventional time-domain thermoreflectance (TDTR) typically probes only near-surface transport due to its restricted modulation frequency range. Here, we employ a frequency-tunable periodic waveform analysis TDTR (PWA-TDTR) technique to perform depth-resolved thermal measurements on three representative systems: epitaxial ε-Ga<sub>2</sub>O<sub>3</sub>/SiC, GaN/Si, and mechanically bonded GaN/diamond. By combining broadband multi-frequency probing with sensitivity-guided joint fitting, we quantitively determine interfacial thermal conductance, layer-specific thermal conductivity, and volumetric heat capacity, without requiring destructive sample preparation. The results reveal that the buried Ga<sub>2</sub>O<sub>3</sub>/SiC interface exhibits weak phonon transmission due to acoustic mismatch; the transition layers in GaN/Si act as phonon-impedance gradients that redistribute heat flux; and the GaN/diamond boundary remains the dominant thermal bottleneck despite diamond's ultrahigh bulk conductivity. These findings demonstrate that the modulation frequency in PWA-TDTR functions as a tunable probe of depth-dependent phonon transport, directly linking frequency-domain thermal response to interfacial energy transmission. Overall, this work positions PWA-TDTR as a versatile platform for investigating buried nonmetal–nonmetal interfaces in next-generation high-power and optoelectronic materials.</div></div>","PeriodicalId":18253,"journal":{"name":"Materials Today Physics","volume":"60 ","pages":"Article 101987"},"PeriodicalIF":9.7,"publicationDate":"2025-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145730897","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
扫码关注我们
求助内容：
应助结果提醒方式：
京公网安备 11010802042870号