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The Origin of Photoinduced Capacitance in Perovskite Solar Cells: Beyond Ionica??toa??Electronic Current Amplification
摘要： Photoinduced capacitances of perovskite solar cells exhibit peculiarities such as an apparently high capacitance and an inductive feature, so-called negative capacitance, which are not easily explained with typical carrier dynamics. Consequently, the origins of the photoinduced capacitances in perovskite solar cells have been intensively debated over the past several years. Here, the photoinduced capacitances of perovskite solar cells are analyzed by impedance spectroscopy. The analysis clarifies that the photoinduced capacitances of perovskite solar cells comprise several Debye relaxation-type capacitance components. Among these components, the photoinduced capacitance in the low-frequency range is attributed to ionic-to-electronic current amplification. However, the photoinduced capacitances in the middle- and high-frequency ranges originate from bipolar injection. The clear elucidation of the origins of the photoinduced capacitances in perovskite solar cells provides comprehensive insights for analyzing properties of perovskites in either the time or frequency domain.
关键词： perovskite solar cells,impedance spectroscopy,ionic to electronic response,negative capacitance
更新于2025-09-23 15:21:01
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[Lecture Notes in Electrical Engineering] Engineering Vibration, Communication and Information Processing Volume 478 (ICoEVCI 2018, India) || Performance Optimization of Self-exited Piezoelectric Vibration Sensor
摘要： Performance evaluation of self-exited piezoelectric vibration sensor with respect to dimensions, shape and material are carried out in the present paper, with an objective to ?nd the design and dimension for which we get optimum performance in terms of frequency response and sensitivity. A new design is proposed based on the parameters discussed, for design COMSOL tool is used. Response for the designed vibration sensor for variation in frequency, with varying dimensions is performed for both differential and lateral loads. Results obtained give us information regarding the operating load, bandwidth, power, voltage and current ranges for best performance.
关键词： Piezoelectric,Optimization,Frequency response,Vibration
更新于2025-09-23 15:21:01
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Analytical solution of dual-phase-lag based heat transfer model in ultrashort pulse laser heating of A6061 and Cu3Zn2 nano film
摘要： The dual-phase-lag model provides the best performance among many existing non-Fourier models and it is particularly more suitable for a short duration of heating. The present literature survey certifies the availability of very few research papers specifically on the development of an exact analytical solution of the dual-phase-lag model illustrating the thermal analysis of ultrashort pulsed laser heating. To address such issues, the present work is intended to develop an exact solution of the thermal response based on the dual-phase-lag heat conduction model utilized for the femtosecond laser heating of nanofilm. The corresponding solution has been derived by a hybrid application of the Duhamel’s theorem and the finite integral transform approach. A comparative thermal analysis has been depicted for the laser heating of 5 nm thin A6061 and Cu3Zn2 nanofilm and the necessity of non-Fourier analysis over the Fourier’s model has been justified. Existing research works are mostly based on gold and chromium nanofilm. As multi-component microstructures of Cu and Al are scientifically proved to be excellent metallic properties (magnetic and optical) and exhibit strong response during energy driven-chemical reactions, the present analysis is focused on these two materials for the femtosecond laser irradiation. In the present analysis, optical properties (absorptivity and reflectivity) of substrate material have been taken into account to develop a better and realistic analytical model than the existing models. The research output notifies that at 0.1 ps of the laser pulse and 100 J m?2 of the laser intensity, developed temperature history reaches the melting point temperature of both the materials in combination with other thermophysical properties. The mathematical modeling also provides the appropriate information about the selection of thermal relaxation time lags for respective materials and this also justifies the experimental observation of relaxation time lags as reported in the literature. The thermal response has been captured for both A6061 and Cu3Zn2 material along the various depths of the nanofilm to evolve the irradiation capacity of the pulsed femtosecond laser source. The present research output is well validated through numerical and experimental research works of existing literature with a negligible variation. The inclusion of optical properties of materials in the present research work plays an important role as it is noticed that the maximum deviation of the temperature difference between with and without optical properties is evidenced as 38.86% and 57.70% for A6061 and Cu3Zn2 nanofilms, respectively.
关键词： Analytical solution,Dual-phase-lag model,Optical properties,Thermal response,Ultrafast pulsed laser
更新于2025-09-23 15:21:01
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Terahertz and Infrared Spectroscopy of Dense and Porous Organosilicate Glass Thin Films
摘要： Wide-range measurements of thin films of SiCxOyHz organosilicate glasses, both dense and porous, deposited on dielectric sapphire substrates and conductive layers of platinum and aluminum, were performed in the THz–IR (5–5000 cm–1) range. This method can be used not only to analyze the evolution of absorption bands in amorphous dielectric films but also to evaluate static conductivity in the framework of the Drude model of conductive layers and to determine the electrodynamic characteristics of organosilicate films with low dielectric permittivity. The original approach proposes a comprehensive analysis of experimental broadband data in order to determine not only the parameters of the individual bands of lattice and molecular vibrations but also the integrated electrodynamic characteristics of the samples obtained.
关键词： simulation of dielectric response spectra,terahertz and infrared spectroscopy,thin films,low-k materials
更新于2025-09-23 15:21:01
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Tricolor luminescence switching by thermal and mechanical stimuli in the crystal polymorphs of pyridyl substituted fluorene
摘要： Stimuli-responsive organic luminescence switching materials have attracted much attention for a decade. Most of the reported examples display a reversible two-color luminescence switching, multicolor switched materials remain extremely lacking due to the un-designability of this kind of smart materials. Herein, we reported a simple organic molecule, 4,4'-(9,9-dimethyl-9H-fluorene-2,7-diyl)dipyridine (MFDP), which exhibited three different crystal polymorphs (V-MFDP, B-MFDP and G-MFDP) with different luminescent colors. Furthermore, the three crystal polymorphs showed a reversible tricolor fluorescent switching from violet to blue and to green upon physical stimuli. The single-crystal structures of the three polymorphs were obtained, and the results indicate that, the stimuli response properties of the three polymorphs come from the different stacking modes induced by intermolecular interactions. The competition between weak π?π stacking and weak hydrogen bonding is the main reason for the the phase transformations among the three crystal polymorphs.
关键词： Fluorene,π–π Stacking,Crystal Structure,Luminescence Switching,Stimuli-response
更新于2025-09-23 15:21:01
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Design of novel self-healing thermoplastic vulcanizates utilizing thermal/magnetic/light triggered shape memory effects
摘要： We designed novel self-healing thermoplastic vulcanizates (TPVs), achieving excellent thermal/magnetic/light triggered shape memory assisted self-healing behavior. Damage on polylactide (PLA)/epoxidized natural rubber (ENR)/Fe3O4 TPVs could be healed via three events synergistically: The shape memory effect of TPVs resulted in the physical contact of damaged surfaces; the desorption-absorption of ENR/Fe3O4 bound rubber promoted inter-diffusion of ENR chains, leading to the self-healing of ENR phase; ENR was grafted onto PLA segment to assist PLA rearranging and entangling again to achieve the repair of TPVs. This self-healing TPV was reported for the first time and paved the way to design next-generation self-healing materials.
关键词： multi-stimuli response,self-healing,PLA/ENR,thermoplastic vulcanizates,shape memory effect
更新于2025-09-23 15:21:01
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Designing low power and high contrast ratio all-optical NOT logic gate for using in optical integrated circuits
摘要： In this paper, a new design of all-optical NOT logic gate is proposed. In this structure, a photonic crystal nano-resonator and three waveguides are used. The nano-resonator is formed by removing two dielectric rods. The contrast ratio for the proposed NOT logic gate is 20.75?dB. The maximum response time and the rate of sending information equal to 0.466?ps and 2.145?Tbit/s, respectively. In addition, very low power consumption, small size, and simple design are the main features of this logic gate. These features allow the designed structure to be used in all-optical switches. To accomplish this, two types of logic gates placement alongside each other in the optical integrated circuits are proposed and investigated. In both types, the logic gates are tested for single use and simultaneous use, and the accuracy of the performance and effect of each on the other is measured. The results clearly show that the two logic gates, along with each other, have acceptable perfor- mance and can easily be used in the optical integrated circuit.
关键词： Nano-resonator,Optical integrated circuit,All-optical NOT logic gate,Response time,Photonic crystal
更新于2025-09-23 15:21:01
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Development of a Terbium-Sensitized Fluorescence Method for Analysis of Silibinin
摘要： Silibinin is a natural flavonoid with potent anticancer properties, as shown in both in vitro and in vivo experiments. Various methods have been used for silibinin analysis. Terbium-sensitized fluorescence methods have been widely used for the determination of drugs in pharmaceutical preparations and biological samples in recent years. The present work is aimed at providing a simple analytical method for the quantitative determination of silibinin in aqueous solutions based on the formation of a fluorescent complex with terbium ion. Terbium concentration, pH, and volume of buffer, the important effective parameters for the determination of silibinin by the proposed method, were optimized using response surface methodology. The fluorescence intensity of silibinin was measured at 545 nm using λex = 334 nm. The developed method was applied for the determination of silibinin in plasma samples after protein precipitation with acetone. Under optimum conditions, the method provided a linear range between 0.10 and 0.50 mg/L, with a coefficient of determination (R2) of 0.997. The LOD and LOQ were 0.034 and 0.112 mg/L, respectively. These results indicate that the developed method is a simple, low-cost, and suitable analytical method for the quantification of silibinin in aqueous solution and plasma samples.
关键词： Response surface methodology,Plasma samples,Quantitative determination,Silibinin,Terbium-sensitized fluorescence
更新于2025-09-23 15:21:01
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Influence of Ag NPs on Silicon Nanocolumns NH <sub/>3</sub> Gas Sensors
摘要： Two NH3 gas sensor devices, Al/Si nanocolumns/n-Si/Al and Al/Ag NPs/Si nanocolumns/n-Si/Al hybrid structures, have been fabricated and tested. A bare silicon nanocolumns layer was synthesized by a laser-assisted electrochemical etching process in HF solutions. The surface morphology of bare Si nanocolumns was modified by incorporating Ag NPs into Si nanocolumns by simple and fast immersions methods in an aqueous solution of AgNO3 to synthesize a hybrid structure. Characteristic features of bare Si nanocolumns and hybrid structure were investigated using scanning electron microscopy, EDS analysis, FTIR spectra, X-ray diffraction, and photoluminescence spectra (PL). The electrical characteristics of sensors with and without NH3 gas were measured at room temperature. The results showed that the nanoparticles grain size, nature, specific surface area (S.S.A) of Ag NPs, and morphological structure of the Si nanocolumns strongly affected the property characteristics. A significant enhancement in sensitivity, response, and recovery times of gas sensor for a hybrid structure was realized after compared with Al/Si nanocolumns/n-Si/Al gas sensor due to the high specific surface area.
关键词： silicon nanocolumns,response time,NH3 gas sensor,sensitivity,Ag NPs,hybrid structure,recovery time
更新于2025-09-23 15:21:01
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A Comparative Study on Neural Network Based Controllers Used in Grid-Interactive Solar System
摘要： This paper proposes a comparative assessment of NN based current controllers followed by hardware validation towards power quality improvement in grid-interactive VSI controlled solar system. The steady state errors, transient disturbances and high current harmonic effects encountered in conventional linear PI and PR controllers are nullified by employing intelligent adaptive current controller. Three adaptive current control strategies viz. ADALINE-LMS, ALLMS, and VLAS-LMS are identified by using artificial neural network topology having been controlled by different weight-regulating algorithms which helps in minimizing current harmonics generated by the widespread use of VSI, non-linear loads, faults and uncertain polluted grid. A comprehensive comparative study is driven from the proposed adaptive controller’s stability and convergence criterion, current magnitudes calculated at different power zones, % overshoot, settling time and power quality and analyzed under numerous operating conditions. From the comparative assessment performed in between conventional and intelligent current controllers, it is confirmed that the intelligent control technique performs best under the non-linear loads and transient conditions whereas all the controllers perform equally good under the linear loads. Proposed methods are simulated in MATLAB/Simulink and their effectiveness is compared in terms of time responses, stability and low-order current harmonics compensation capability. The robustness of the intelligent current controller is established through the experimental performances using dSPACE RTI 1202.
关键词： grid-interactive solar,power quality,stability,dSPACE,neural network (NN),current controllers (cc),time response
更新于2025-09-23 15:21:01