Pub Date : 2025-12-02DOI: 10.1016/j.cap.2025.12.002
Hue Tran , Yugyeong Je , Hyunjeong Jeong , Eleanor E.B. Campbell , Ki Kang Kim , Sang Wook Lee
The energy barrier height of ZnO microwire electrical contacts is tuned by inducing piezoelectric polarization charges at the local metal-semiconductor interface when a mechanical deformation is applied to the ZnO microwire. Strain is introduced in the individual ZnO microwire by compressive stress applied along the axial direction, which controllably bends the microwire, observed in an optical microscope. As a result, the metal-semiconductor local contact can transform from Schottky to Ohmic and vice versa. This work demonstrates a simple method for controlling the electrical properties of ZnO nanowires to achieve reversible tuning between Schottky and Ohmic contact on one device by combining in-situ measurement with mechanical manipulation. This can contribute to the development of multifunctional and Ohmic/Schottky-based sensors, switches, rectifiers, and other functional electronic devices.
{"title":"Reversible conversion between Schottky and ohmic contacts of zinc oxide microwire under piezoelectric potential manipulation","authors":"Hue Tran , Yugyeong Je , Hyunjeong Jeong , Eleanor E.B. Campbell , Ki Kang Kim , Sang Wook Lee","doi":"10.1016/j.cap.2025.12.002","DOIUrl":"10.1016/j.cap.2025.12.002","url":null,"abstract":"<div><div>The energy barrier height of ZnO microwire electrical contacts is tuned by inducing piezoelectric polarization charges at the local metal-semiconductor interface when a mechanical deformation is applied to the ZnO microwire. Strain is introduced in the individual ZnO microwire by compressive stress applied along the axial direction, which controllably bends the microwire, observed in an optical microscope. As a result, the metal-semiconductor local contact can transform from Schottky to Ohmic and <em>vice versa</em>. This work demonstrates a simple method for controlling the electrical properties of ZnO nanowires to achieve reversible tuning between Schottky and Ohmic contact on one device by combining <em>in-situ</em> measurement with mechanical manipulation. This can contribute to the development of multifunctional and Ohmic/Schottky-based sensors, switches, rectifiers, and other functional electronic devices.</div></div>","PeriodicalId":11037,"journal":{"name":"Current Applied Physics","volume":"83 ","pages":"Pages 22-27"},"PeriodicalIF":3.1,"publicationDate":"2025-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145692528","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In the solution-processing method of perovskites, selecting appropriate solvents for each precursor is crucial for synthesizing homogeneous perovskite films, as the interaction energy and mechanism between each solvent and precursor vary significantly. In this study, we used dimethylacetamide (DMAc) as the host solvent instead of dimethylformamide to match the Hansen solubility parameters (HSP) with N-methyl-2-pyrrolidone (NMP) and anti-solvent. DMAc-based perovskite facilitates the formation of intermediate phase with NMP due to well-matched HSP, resulting in formation of a glossy perovskite film. However, the power conversion efficiency (PCE) of DMAc-based perovskite solar cells did not improve, primarily because of the formation of small grains. Although methylammonium chloride (MACl) was introduced as an additive to promote grain growth, no significant enhancement in the PCE was observed, likely due to the low interaction energy between MACl and NMP. These findings enhance our understanding of solvent-precursor interactions by applying HSP theory and MACl additive.
{"title":"Solvent–precursor interaction engineering for formamidinium-based perovskites: Role of dimethylacetamide, N-methyl-2-pyrrolidone, and methylammonium chloride in film formation and device performance","authors":"Muntae Hwang, Il-Wook Cho, Hyunbok Lee, Mee-Yi Ryu","doi":"10.1016/j.cap.2025.11.010","DOIUrl":"10.1016/j.cap.2025.11.010","url":null,"abstract":"<div><div>In the solution-processing method of perovskites, selecting appropriate solvents for each precursor is crucial for synthesizing homogeneous perovskite films, as the interaction energy and mechanism between each solvent and precursor vary significantly. In this study, we used dimethylacetamide (DMAc) as the host solvent instead of dimethylformamide to match the Hansen solubility parameters (HSP) with N-methyl-2-pyrrolidone (NMP) and anti-solvent. DMAc-based perovskite facilitates the formation of intermediate phase with NMP due to well-matched HSP, resulting in formation of a glossy perovskite film. However, the power conversion efficiency (PCE) of DMAc-based perovskite solar cells did not improve, primarily because of the formation of small grains. Although methylammonium chloride (MACl) was introduced as an additive to promote grain growth, no significant enhancement in the PCE was observed, likely due to the low interaction energy between MACl and NMP. These findings enhance our understanding of solvent-precursor interactions by applying HSP theory and MACl additive.</div></div>","PeriodicalId":11037,"journal":{"name":"Current Applied Physics","volume":"83 ","pages":"Pages 15-21"},"PeriodicalIF":3.1,"publicationDate":"2025-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145692525","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-01DOI: 10.1016/j.cap.2025.11.014
Kyu-Hyun Park, Byung-Hoon Kim, Changyeon Baek, Yun-Gi Jeong, Min-Ku Lee, Gyoung-Ja Lee
This study investigates the compositional dependence of piezoelectric and thermal properties in (1–x)BiFeO3–xBaTiO3 ceramics and evaluates their applicability in high-temperature accelerometer applications. Four compositions (x = 0.25, 0.30, 0.33, 0.35) were synthesized and analyzed for their structural, electrical, and thermal behaviors. The x = 0.25 composition, despite a relatively low piezoelectric coefficient (∼107 pC/N), exhibited the highest mechanical quality factor (∼67) and depolarization temperature (∼450 °C), along with superior resistance to thermally and mechanically induced degradation. When used in compression-mode accelerometers, this composition showed the highest sensitivity (∼23.4 pC/g) and operated up to ∼380 °C. These results suggest that reliable high-temperature sensor performance is influenced not only by the piezoelectric coefficient but also by thermal and mechanical stability, highlighting the importance of comprehensive compositional optimization. Additionally, a strong correlation was observed between the in situ piezoelectric response of the ceramics and the temperature-dependent sensitivity of the assembled sensors.
{"title":"Dependence of piezoelectric properties and thermal stability of (1–x)BiFeO3–xBaTiO3 ceramics in relation to accelerometer performance","authors":"Kyu-Hyun Park, Byung-Hoon Kim, Changyeon Baek, Yun-Gi Jeong, Min-Ku Lee, Gyoung-Ja Lee","doi":"10.1016/j.cap.2025.11.014","DOIUrl":"10.1016/j.cap.2025.11.014","url":null,"abstract":"<div><div>This study investigates the compositional dependence of piezoelectric and thermal properties in (1–<em>x</em>)BiFeO<sub>3</sub>–<em>x</em>BaTiO<sub>3</sub> ceramics and evaluates their applicability in high-temperature accelerometer applications. Four compositions (<em>x</em> = 0.25, 0.30, 0.33, 0.35) were synthesized and analyzed for their structural, electrical, and thermal behaviors. The <em>x</em> = 0.25 composition, despite a relatively low piezoelectric coefficient (<em>∼</em>107 pC/N), exhibited the highest mechanical quality factor (<em>∼</em>67) and depolarization temperature (<em>∼</em>450 °C), along with superior resistance to thermally and mechanically induced degradation. When used in compression-mode accelerometers, this composition showed the highest sensitivity (∼23.4 pC/g) and operated up to ∼380 °C. These results suggest that reliable high-temperature sensor performance is influenced not only by the piezoelectric coefficient but also by thermal and mechanical stability, highlighting the importance of comprehensive compositional optimization. Additionally, a strong correlation was observed between the in situ piezoelectric response of the ceramics and the temperature-dependent sensitivity of the assembled sensors.</div></div>","PeriodicalId":11037,"journal":{"name":"Current Applied Physics","volume":"83 ","pages":"Pages 38-45"},"PeriodicalIF":3.1,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145692524","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-01DOI: 10.1016/j.cap.2025.11.013
Garam Bae , Wooseok Song
We report a hydrogen-assisted chemical vapor deposition (CVD) strategy for the controlled synthesis of triangular-shaped WS2 flakes and demonstrate their integration with graphene to construct optoelectronic heterostructures. By systematically tuning the H2 flow rate during WS2 growth, we modulate flake density and layer thickness. Raman and XPS analyses reveal highly crystalline bilayer WS2 with minimal contamination. Upon transferring graphene onto WS2 flakes, we observe distinct doping-induced Raman shifts and p-type behavior in field-effect transport. Notably, the WS2–graphene heterostructure exhibits photocurrent quenching under UV irradiation, attributed to efficient interfacial charge transfer. This study elucidates the role of H2 in nucleation control and highlights the potential of WS2–graphene heterostructures for photodetection applications.
{"title":"WS2–graphene heterostructures with hydrogen-controlled morphology: Interfacial charge transfer and negative photoresponse","authors":"Garam Bae , Wooseok Song","doi":"10.1016/j.cap.2025.11.013","DOIUrl":"10.1016/j.cap.2025.11.013","url":null,"abstract":"<div><div>We report a hydrogen-assisted chemical vapor deposition (CVD) strategy for the controlled synthesis of triangular-shaped WS<sub>2</sub> flakes and demonstrate their integration with graphene to construct optoelectronic heterostructures. By systematically tuning the H<sub>2</sub> flow rate during WS<sub>2</sub> growth, we modulate flake density and layer thickness. Raman and XPS analyses reveal highly crystalline bilayer WS<sub>2</sub> with minimal contamination. Upon transferring graphene onto WS<sub>2</sub> flakes, we observe distinct doping-induced Raman shifts and <em>p</em>-type behavior in field-effect transport. Notably, the WS<sub>2</sub>–graphene heterostructure exhibits photocurrent quenching under UV irradiation, attributed to efficient interfacial charge transfer. This study elucidates the role of H<sub>2</sub> in nucleation control and highlights the potential of WS<sub>2</sub>–graphene heterostructures for photodetection applications.</div></div>","PeriodicalId":11037,"journal":{"name":"Current Applied Physics","volume":"83 ","pages":"Pages 8-14"},"PeriodicalIF":3.1,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145692526","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-26DOI: 10.1016/j.cap.2025.11.009
Woojun Lee , Chaewon Kim , Taeyoung Choi , Taehyun Kim
Quantum systems are highly sensitive to environmental noise, leading to drifts in experimental parameters. To enhance entanglement gate fidelity in multiqubit trapped-ion systems, laser amplitude modulation has proven robust against frequency drifts. In this study, we extend this technique by actively optimizing the laser amplitude sequence using a user-defined objective function. This function evaluates fidelities across a broad range of trap frequencies and identifies amplitude solutions under practical laser power constraints. We select the most robust solution—maintaining fidelity above 99.5 % across the widest frequency range—and apply it to various drift types, including linear, sinusoidal, and exponential deviations. Our approach offers a flexible framework for integrating different optimization algorithms and objective functions to maintain high-fidelity gate operations in noisy quantum environments.
{"title":"Computational optimization of two-qubit entangling gates in trapped-ion systems under system frequency drift","authors":"Woojun Lee , Chaewon Kim , Taeyoung Choi , Taehyun Kim","doi":"10.1016/j.cap.2025.11.009","DOIUrl":"10.1016/j.cap.2025.11.009","url":null,"abstract":"<div><div>Quantum systems are highly sensitive to environmental noise, leading to drifts in experimental parameters. To enhance entanglement gate fidelity in multiqubit trapped-ion systems, laser amplitude modulation has proven robust against frequency drifts. In this study, we extend this technique by actively optimizing the laser amplitude sequence using a user-defined objective function. This function evaluates fidelities across a broad range of trap frequencies and identifies amplitude solutions under practical laser power constraints. We select the most robust solution—maintaining fidelity above 99.5 % across the widest frequency range—and apply it to various drift types, including linear, sinusoidal, and exponential deviations. Our approach offers a flexible framework for integrating different optimization algorithms and objective functions to maintain high-fidelity gate operations in noisy quantum environments.</div></div>","PeriodicalId":11037,"journal":{"name":"Current Applied Physics","volume":"83 ","pages":""},"PeriodicalIF":3.1,"publicationDate":"2025-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145692527","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-25DOI: 10.1016/j.cap.2025.11.008
Gichan Son , Sejoong Kim , Jeongwoo Kim
Trigonal selenium (Se) and tellurium (Te), with their one-dimensional helical structures, exhibit unique chirality-driven physical phenomena. Here, we systematically investigate the influence of various XC functionals–ranging from conventional generalized gradient approximations (GGA) and meta-GGA to hybrid functionals–on the electronic and phononic band structures of Se and Te. Our calculations reveal that while meta-GGA functionals provide little improvement in electronic structures over conventional GGA, the hybrid functional HSE06 predicts a significant widening of the electronic band gap. This effect is attributed to an enhanced charge localization within the intra-chain covalent bonds, more evident in trigonal Se than in Te. Moreover, the strengthened intra-chain bonding in the HSE06 calculation leads to a hardening of high-frequency intra-chain modes and a softening of low-frequency inter-chain modes. Remarkably, trigonal Se exhibits an unusual anharmonic hardening of high-frequency optical modes under isobaric conditions, originating from the large disparity between strong intra-chain and weak inter-chain force constants.
{"title":"Exchange-correlation functional effects on electronic and phononic band structures of helical Se and Te","authors":"Gichan Son , Sejoong Kim , Jeongwoo Kim","doi":"10.1016/j.cap.2025.11.008","DOIUrl":"10.1016/j.cap.2025.11.008","url":null,"abstract":"<div><div>Trigonal selenium (Se) and tellurium (Te), with their one-dimensional helical structures, exhibit unique chirality-driven physical phenomena. Here, we systematically investigate the influence of various XC functionals–ranging from conventional generalized gradient approximations (GGA) and meta-GGA to hybrid functionals–on the electronic and phononic band structures of Se and Te. Our calculations reveal that while meta-GGA functionals provide little improvement in electronic structures over conventional GGA, the hybrid functional HSE06 predicts a significant widening of the electronic band gap. This effect is attributed to an enhanced charge localization within the intra-chain covalent bonds, more evident in trigonal Se than in Te. Moreover, the strengthened intra-chain bonding in the HSE06 calculation leads to a hardening of high-frequency intra-chain modes and a softening of low-frequency inter-chain modes. Remarkably, trigonal Se exhibits an unusual anharmonic hardening of high-frequency optical modes under isobaric conditions, originating from the large disparity between strong intra-chain and weak inter-chain force constants.</div></div>","PeriodicalId":11037,"journal":{"name":"Current Applied Physics","volume":"82 ","pages":"Pages 22-29"},"PeriodicalIF":3.1,"publicationDate":"2025-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145616097","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-20DOI: 10.1016/j.cap.2025.11.006
Taehee Noh, Cheol Jun Kim, Jae Yeob Lee, Minkyung Ku, Tae Hoon Kim, Minu Kang, Hyeon Su Seong, Seung Jin Kang, Bo Soo Kang
Memristor with analog resistive switching (RS) characteristics has potential for effective utilization in hardware neuromorphic systems. We investigated the response by applying identical pulses to filamentary RS devices to induce synaptic functions. This study examined the effects of inserting Al2O3 or HfO2 into Ta2O5-based RS device on its switching behavior to analyze long-term plasticity. Abrupt potentiation (or depression) behavior in Ta2O5 single layer structure may be inappropriate for neuromorphic applications. Thus, we proposed bilayer structures to alleviate abrupt conductance change. More linear and symmetric conductance modulation was confirmed in Ta2O5/HfO2 device compared to Ta2O5/Al2O3 device: exhibiting high potential as a synaptic device for neuromorphic computing. High learning accuracy was verified in Ta2O5/HfO2 device through neural network simulation. Among all devices, its RS behavior was most consistent. This could originate from fewer remaining nucleation sites for reformation of conductive filament (CF). This stable CF reformation might contribute to reliable synaptic behavior.
{"title":"Enhanced analog switching in Ta2O5/HfO2 bilayer resistive switching device for improved synaptic behavior in neuromorphic computing","authors":"Taehee Noh, Cheol Jun Kim, Jae Yeob Lee, Minkyung Ku, Tae Hoon Kim, Minu Kang, Hyeon Su Seong, Seung Jin Kang, Bo Soo Kang","doi":"10.1016/j.cap.2025.11.006","DOIUrl":"10.1016/j.cap.2025.11.006","url":null,"abstract":"<div><div>Memristor with analog resistive switching (RS) characteristics has potential for effective utilization in hardware neuromorphic systems. We investigated the response by applying identical pulses to filamentary RS devices to induce synaptic functions. This study examined the effects of inserting Al<sub>2</sub>O<sub>3</sub> or HfO<sub>2</sub> into Ta<sub>2</sub>O<sub>5</sub>-based RS device on its switching behavior to analyze long-term plasticity. Abrupt potentiation (or depression) behavior in Ta<sub>2</sub>O<sub>5</sub> single layer structure may be inappropriate for neuromorphic applications. Thus, we proposed bilayer structures to alleviate abrupt conductance change. More linear and symmetric conductance modulation was confirmed in Ta<sub>2</sub>O<sub>5</sub>/HfO<sub>2</sub> device compared to Ta<sub>2</sub>O<sub>5</sub>/Al<sub>2</sub>O<sub>3</sub> device: exhibiting high potential as a synaptic device for neuromorphic computing. High learning accuracy was verified in Ta<sub>2</sub>O<sub>5</sub>/HfO<sub>2</sub> device through neural network simulation. Among all devices, its RS behavior was most consistent. This could originate from fewer remaining nucleation sites for reformation of conductive filament (CF). This stable CF reformation might contribute to reliable synaptic behavior.</div></div>","PeriodicalId":11037,"journal":{"name":"Current Applied Physics","volume":"83 ","pages":"Pages 1-7"},"PeriodicalIF":3.1,"publicationDate":"2025-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145645620","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-14DOI: 10.1016/j.cap.2025.11.007
Wenke Shi , Chenglong Yu , Jin Yan , Chenjie Miao , Siqi She , Lin Ji , Wenxian Zhang , Yuandong Jia , Yinbowen Zhang , Zeming Zhang , Yi Zhang , Hongqing Huo , Zhong Zhao
Quantum yield (QY) is a critical parameter for assessing charge management efficiency. This study established a precise measurement platform to investigate the QY of gold (Au), niobium (Nb), and silicon carbide (SiC) thin films under 255 nm ultraviolet illumination. Results demonstrated that surface contamination significantly reduces the work function (WF). Nb exhibited the lowest WF (3.89 eV) and highest QY (3.3 × 10−6). Applying a ±9 V bias increased the QY of Au by 5.8 times, a phenomenon explained by image potential barrier reduction. Furthermore, for surface-contaminated Au, the QY decreased sharply with increasing incident angle, indicating that the bulk emission mechanism predominates over the vectorial photoelectric effect. These findings provide valuable insights to help optimize space-charge management systems.
{"title":"Investigation of key factors influencing UV-induced quantum yield in charge management","authors":"Wenke Shi , Chenglong Yu , Jin Yan , Chenjie Miao , Siqi She , Lin Ji , Wenxian Zhang , Yuandong Jia , Yinbowen Zhang , Zeming Zhang , Yi Zhang , Hongqing Huo , Zhong Zhao","doi":"10.1016/j.cap.2025.11.007","DOIUrl":"10.1016/j.cap.2025.11.007","url":null,"abstract":"<div><div>Quantum yield (QY) is a critical parameter for assessing charge management efficiency. This study established a precise measurement platform to investigate the QY of gold (Au), niobium (Nb), and silicon carbide (SiC) thin films under 255 nm ultraviolet illumination. Results demonstrated that surface contamination significantly reduces the work function (WF). Nb exhibited the lowest WF (3.89 eV) and highest QY (3.3 × 10<sup>−6</sup>). Applying a ±9 V bias increased the QY of Au by 5.8 times, a phenomenon explained by image potential barrier reduction. Furthermore, for surface-contaminated Au, the QY decreased sharply with increasing incident angle, indicating that the bulk emission mechanism predominates over the vectorial photoelectric effect. These findings provide valuable insights to help optimize space-charge management systems.</div></div>","PeriodicalId":11037,"journal":{"name":"Current Applied Physics","volume":"82 ","pages":"Pages 1-14"},"PeriodicalIF":3.1,"publicationDate":"2025-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145532359","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-10DOI: 10.1016/j.cap.2025.11.005
V.C. Suchitra , R. Athira , V. Anunanda , Sithara , S.P. Vaiga Sagar , P.C. Rilu Fathima , K. Fathima Rameeza , T.A. Ramseena , N.N. Binitha
Flexible supercapacitors are essential for wearable electronics due to their mechanical resilience. This study uses soluble starch, a carbohydrate-based milling agent, for the mechanochemical exfoliation of graphite into few-layered, less-defective graphene. Hydrothermal treatment of the milled mixture containing starch yields carbon dot (CD)-decorated graphene. Material characterization confirms the turbostratic graphene structure, its edge functionalities, and CD distribution over the sheets. Electrochemical evaluation in a three-electrode system shows a specific capacitance of 614.1 F/g at 3 A/g, low charge transfer resistance, 98.3 % coulombic efficiency, and 100 % capacitance retention over 12,000 cycles. CD/graphene follows more of a pseudocapacitive mechanism with 80 % diffusive contribution. A flexible symmetric device using CD/graphene achieves 99.6 F/g (139.45 mF/cm2) specific capacitance, 13.8 Wh/kg energy density, and 714.3 W/kg power density. It retains 100 % capacitance after 2000 cycles and performs reliably under bending, twisting and folding. Three devices in series successfully light a green LED and decorative light, demonstrating real-world applicability.
{"title":"Graphene electrodes decorated with starch-derived carbon dots for flexible supercapacitors","authors":"V.C. Suchitra , R. Athira , V. Anunanda , Sithara , S.P. Vaiga Sagar , P.C. Rilu Fathima , K. Fathima Rameeza , T.A. Ramseena , N.N. Binitha","doi":"10.1016/j.cap.2025.11.005","DOIUrl":"10.1016/j.cap.2025.11.005","url":null,"abstract":"<div><div>Flexible supercapacitors are essential for wearable electronics due to their mechanical resilience. This study uses soluble starch, a carbohydrate-based milling agent, for the mechanochemical exfoliation of graphite into few-layered, less-defective graphene. Hydrothermal treatment of the milled mixture containing starch yields carbon dot (CD)-decorated graphene. Material characterization confirms the turbostratic graphene structure, its edge functionalities, and CD distribution over the sheets. Electrochemical evaluation in a three-electrode system shows a specific capacitance of 614.1 F/g at 3 A/g, low charge transfer resistance, 98.3 % coulombic efficiency, and 100 % capacitance retention over 12,000 cycles. CD/graphene follows more of a pseudocapacitive mechanism with 80 % diffusive contribution. A flexible symmetric device using CD/graphene achieves 99.6 F/g (139.45 mF/cm<sup>2</sup>) specific capacitance, 13.8 Wh/kg energy density, and 714.3 W/kg power density. It retains 100 % capacitance after 2000 cycles and performs reliably under bending, twisting and folding. Three devices in series successfully light a green LED and decorative light, demonstrating real-world applicability.</div></div>","PeriodicalId":11037,"journal":{"name":"Current Applied Physics","volume":"81 ","pages":"Pages 57-65"},"PeriodicalIF":3.1,"publicationDate":"2025-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145526601","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-07DOI: 10.1016/j.cap.2025.11.004
Zhong-Mei Huang , Wei-Qi Huang , Yin-Lian Li , Fei-Yian Yuang , Shi-Rong Liu
The Si-Ge-Si multiple quantum wells (MQW) is fabricated by pulsed laser deposition (PLD) method, in which the nanolayers are crystallized in the annealing and the coherent electron beam irradiation processes. It is discovered in the simulating calculation that the magical distribution of electron states with multi-peak shape occurs and the direct-gap structure is obtained in the MQW. It is interesting that the enhanced emission peaks with the multi-longitudinal-mode near 1150 and 1550 nm are observed in the photoluminescence (PL) spectra measured in the MQW, which have the emission characteristics of direct-gap near Si band edge or Ge band edge due to elevation of conduction valley at X point or L point over the valley at Γ point in the quantum system. The results in experiment and calculation exhibit that the peaks number in the multi-longitudinal-mode emission increases with increasing MQW number, and the emission wavelength can enter into the optic-communication windows by changing MQW number near Ge band edge. The new effects are discovered, in which the physical model from the multi-quantum-well to the electron states with multi-peak shape for better emission is built according to the data in the investigation. This kind of emission with the multi-longitudinal-mode will have a good application in ultra-fast laser through locking modes and in optical source on silicon chip for optic-communication.
{"title":"Magical distribution of electron states for Emission in Si-Ge-Si Multiple Quantum Wells","authors":"Zhong-Mei Huang , Wei-Qi Huang , Yin-Lian Li , Fei-Yian Yuang , Shi-Rong Liu","doi":"10.1016/j.cap.2025.11.004","DOIUrl":"10.1016/j.cap.2025.11.004","url":null,"abstract":"<div><div>The Si-Ge-Si multiple quantum wells (MQW) is fabricated by pulsed laser deposition (PLD) method, in which the nanolayers are crystallized in the annealing and the coherent electron beam irradiation processes. It is discovered in the simulating calculation that the magical distribution of electron states with multi-peak shape occurs and the direct-gap structure is obtained in the MQW. It is interesting that the enhanced emission peaks with the multi-longitudinal-mode near 1150 and 1550 nm are observed in the photoluminescence (PL) spectra measured in the MQW, which have the emission characteristics of direct-gap near Si band edge or Ge band edge due to elevation of conduction valley at X point or L point over the valley at Γ point in the quantum system. The results in experiment and calculation exhibit that the peaks number in the multi-longitudinal-mode emission increases with increasing MQW number, and the emission wavelength can enter into the optic-communication windows by changing MQW number near Ge band edge. The new effects are discovered, in which the physical model from the multi-quantum-well to the electron states with multi-peak shape for better emission is built according to the data in the investigation. This kind of emission with the multi-longitudinal-mode will have a good application in ultra-fast laser through locking modes and in optical source on silicon chip for optic-communication.</div></div>","PeriodicalId":11037,"journal":{"name":"Current Applied Physics","volume":"82 ","pages":"Pages 15-21"},"PeriodicalIF":3.1,"publicationDate":"2025-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145616187","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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