Series Resistance Values Research Articles

Impedance and Interface States Depending on Frequency Analysis of Al/(ZnFe2O4-PVA)/p-Si Structures

This study investigates the properties of a film made of zinc ferrite (ZnFe2O4) doped polyvinyl alcohol (PVA). The film is sandwiched between an aluminum (Al) and p-Si semiconductor layers, and electrical measurements are conducted on the structure in a wide scope of frequency besides voltage. The study evaluates the impacts of the ZnFe2O4-PVA interlayer on surface-states (NSS), and complex-impedance (Z* = Z' - jZ''). A remarkable impact of the values of series resistance (RS) and the interlayer on the capacitance-voltage (C-V) and conductance-voltage (G/ω-V) data has been observed at moderate and high frequencies. Hence, the C and G/ω versus V qualities were modified at high frequency to eliminate the outcome of RS. The Hill-Coleman approach was utilized to estimate the values for NSS. Experimental results confirm that both the NSS , RS and the interlayer in the metal-polymer-semiconductor (MPS) structures are critical factors that significantly alter the electrical and dielectric properties. The analysis of the results obtained from the impedance study showed divergent behavior. It was observed that the impedance values increase in the low frequency, while they diminish in the higher frequencies, as a result of the mutual effect between the interface and the dipole polarization. The study suggests that due to its high dielectric value, the ZnFe2O4-PVA interlayer may be a better alternative to conventional insulators for charge/energy storage.

Impact of voltage and frequency on electrical characteristics of MIS capacitors with triphenylamine layer

This study examines the effect of triphenylamine (TPA) interlayers on the electrical properties of Al/TPA/p-Si metal-interlayer/insulator material-semiconductor (MIS) capacitors. Using Gaussian software, TPA molecular structure was optimized, and HOMO-LUMO energy levels were simulated. Capacitance-conductance-voltage (C-G-V) measurements were performed at room temperature over −4 V to +4 V and 50 kHz–700 kHz. AFM and SEM analysis showed TPA films were smooth with a uniform thickness of about 178 nm. The C-V characteristics revealed a frequency-dependent decrease in capacitance, indicating a continuous distribution of interface states. Barrier height (ΦB) increased from 0.305 eV at 50 kHz to 0.655 eV at 700 kHz, while the active interface trap density (Dit) decreased from 6.73 × 1012 eV−1 cm−2 to 3.23 × 1011 eV−1 cm−2. Additionally, the accumulating region exhibited low series resistance values (between 6.88 and 8.44 Ω). These results suggest that TPA thin films are effective for MIS capacitors.

Impact of carbon electrode layer on the series resistance and fill factor of CH3NH3PbI3 perovskite solar cell

Methylammonium lead triiodide (CH3NH3PbI3) is a metal halide perovskite that is attracting great attention owing to its remarkable optoelectronic properties especially in perovskite solar cells (PSCs) and perovskite light-emitting devices (PLEDs). In this work, the impact of the number of carbon electrode layers on the photovoltaic parameters and impedance spectra of hole transport material-free (HTM-free) glass/FTO/c-TiO2/m-TiO2/m-ZrO2/carbon monolithic PSCs is examined. A significant influence of the carbon electrode layers on the fill factor and series resistance is revealed. The optimum values of fill factor and series resistance are observed when a 3-layered carbon electron is used in the PSC. This is due to higher charge transportation, higher electrical conductivity, higher electron mobility, and lower recombination losses.

Frequency-dependent capacitance and conductance characteristics and current transport mechanisms of Schottky diodes with TPA-IFA organic interfacial layer

In this study, a Schottky barrier diode with an Al/TPA-IFA/p-Si structure was fabricated using spin coating and thermal evaporation methods. Using forward and reverse bias I–V measurement, we examined the key electrical characteristics of the Al/TPA-IFA/p-Si diode, including Φb, n, Rs, and Nss; we also estimated VD, NA, EF, ∆Φb, WD, Φb and Nss using C–V measurements under the different frequencies (10, 50, 100, 500 kHz, and 1 MHz) at room temperature. Using I–V data and the Thermionic Emission (TE) theory, basic electrical parameters such as ideality factor ( n ), and barrier height ( Φb ) values were computed as 3.01 and 0.716 eV. The fundamental diode parameters are highly frequency-dependent. It was also found that the series Resistance ( Rs ) values reduced with increasing frequency, but the barrier height ( Φb ) and the width of the depletion layer ( WD ) increased. It was found that when frequency increased, the diode capacitance reduced for our new Schottky-type diode. The diode’s potential conduction mechanisms were examined through the utilization of reverse lnI−V0.5 and forward lnI−V graphs. The transport properties of Al/TPA-IFA/p-Si diode are primarily governed by ohmic conduction, Space Charge Limited Current (SCLC), and Trap Charge Limited Current (TCLC) mechanisms at low, moderate, and high voltages, respectively. It was concluded that the Poole–Frenkel Emission (PFE) mechanism was dominant for the Al/TPA-IFA/p-Si diode. Ultimately, the findings confirmed that the TPA-IFA-based diode could be obtained for the electronic application.

Enhanced photodiode performance: Au/boron-dipyrromethene/n-Si/Ag structure unveiling high photosensitivity and efficiency

In this study, the classical boron-dipyrromethene (4,4- difuoro-4-borata-3a-azonia-4a-aza-s-indacene, BODIPY) unit (C1), its halogenated derivative (C2), and disytryl derivative (C3), which are known for their absorption properties in the near-infrared (NIR) region, were synthesized. Chemical and photophysical investigations were carried out to reveal the complex features of the molecules using a range of spectroscopic techniques and their energies were calculated by Density Functional Theory (DFT) with the same basis set. The BODIPY thin films were coated on n-Si substrates using a spin coater to examine the effect of interlayer on photodiode/photovoltaic properties and Au/BODIPY (C1, C2, C3)/n-Si/Ag photodiodes having rectifying behavior were fabricated. The thermionic emission theory (TET) and modified Norde’s functions were utilized to determine the rectification ratio, ideality factor, series resistance, and barrier height values of diodes. The values of barrier height, ideality factor, and rectification ratio at ± 2 V were calculated as 0.81 eV, 1.83 and 2.47x103 for the Au/C1/n-Si/Ag diode, 0.83 eV, 1.63, and 7.06 x103 for the Au/C2/n-Si/Ag diode and 0.84 eV, 1.51 and 2.14x104 for the Au/C3/n-Si/Ag diode in the dark from the TET, respectively. The values of FF (%) and efficiency were calculated as 38 and 1.51 for the Au/C1/n-Si/Ag diode, 47 and 2.03 for the Au/C2/n-Si/Ag diode, and 56 and 3.68 for the Au/C3/n-Si/Ag diode under 100 mW/cm2 illumination, respectively. With remarkable electrical properties, the Au/C3/n-Si/Ag photodiode stood out among the others, performing better in both dark and light conditions. Therefore, the produced diodes based on the BODIPY thin film can be employed as photodiodes/photovoltaics in optoelectronic applications.

Super capacitive electrode performance analysis of facile synthesized α-Fe2O3 aerogel and its nanocomposite with in-situ formed polyaniline (α-Fe2O3/PANI)

This paper presents the synthesis of an α-Fe2O3-assisted polyaniline (α-Fe2O3/PANI) nanocomposite using a straightforward two-step process. Initially, α-Fe2O3 aerogels with cratered nanohexagon structures are synthesized through a solution combustion method assisted by noni (Morinda citrifolia) fruit extract. In the second step, these nanohexagons facilitate the preparation of α-Fe2O3/PANI via in-situ chemical oxidative polymerization of anilinium chloride. The structural, optical, and morphological properties were characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy with energy-dispersive X-ray analysis (SEM-EDAX). Electrical conductivity, wettability, and electrochemical properties of the prepared materials were assessed. The results indicate that the 2D cratered α-Fe2O3 aerogel is effectively embedded within PANI, forming a modified nano α-Fe2O3/PANI composite. The composite exhibited altered DC conductivity and electrolyte wettability. After 200 cycles of cyclic voltammetry (CV), the specific capacitance of the nano α-Fe2O3/PANI was determined to be 153 Fg⁻¹ at a scan rate of 10 mVs⁻¹, retaining approximately 90 % of its cycle stability. Electrochemical impedance spectroscopy (EIS) revealed significantly lower charge transfer and equivalent series resistance values for the nano α-Fe2O3/PANI electrode compared to the pure α-Fe2O3-based electrode. Galvanostatic charge-discharge (GCD) tests further demonstrated the superior electrochemical performance of the α-Fe2O3/PANI nanocomposite electrode. Therefore, this α-Fe2O3/PANI is an advanced conducting polymeric electrode for electrochemical applications.

Influence of 700 keV O3+ ion implantation on current transport properties of Cr/p-GaN SBD’s

In the present study we show a detailed investigation into the influence of 700 keV O3+ ion implantation in Cr/p-GaN SBDs on electrical characteristics / current transport properties. Also the damage events along the trajectory of the ion beam were quantitatively estimated through SRIM and TRIM simulations. The Current-voltage (I-V) characteristics were analyzed using different methods such as Cheung and Cheung's method and Norde’s method to obtain different electrical parameters. The values of n and ϕB decrease up to a fluence of 1 × 1014 ions cm−2, and show a fractional increase at a fluence of 1 × 1015 ions cm−2. Further, a drastic increase in values of series resistance (RS ) of SBDs with an increase in fluence was observed. In the forward-bias voltage regions, the Cr/p-GaN SBDs conduction mechanism shows an increasingly ohmic behavior with an increase in fluence, which may be attributed to thermally generated carriers. At low voltage, the reverse current conduction mechanism is due to Poole-Frenkel emission. For the high voltage region, Schottky emission mechanism becomes more prominent. The changes in electrical parameters are closely related to the defect and damage profiles estimated through SRIM/TRIM simulations, which are strongly dependent on the dose of the 700 keV O3+ ion implantation. Additionally, we found that at high doses, the charge transport mechanism changes, with additional defects affecting not only the thermionic emission mechanism but also various current transport mechanisms.

Activated carbon derived from corncob via hydrothermal carbonization as a promising electrode for supercapacitors

Activated carbon has been synthesized from corncob via hydrothermal treatment at 200 °C for 7 h with and without activating agents, followed by carbonization at 400 °C for 3 h. The X-ray diffraction patterns show peaks corresponding to the amorphous and graphitic carbon phases. The SEM studies reveal meso and macro pores. The H3PO4 treated sample (CC-H-400) shows the highest Brunauer-Emmett-Teller surface area (68.54 m2 g-1). Raman spectra indicate the typical D and G bands. The CC-H-400 shows the highest specific capacitance value of 41 F g-1 among all the samples. The energy and power density values of the supercapacitor working electrode in a three-electrode setup are 5.7 W h kg-1 and 500.4 W kg-1, respectively, for the CC-H-400. Furthermore, the CC-H-400 exhibits excellent stability with a retention rate of 88 % after 2000 charge-discharge cycles at 10 A g-1 without any shape change, as well as a low equivalence series resistance (ESR) value of 3.96 Ω.

CoMnS@rGO nanocomposite grown on NF for high-performance supercapacitor-battery hybrid device and advancing electrochemical sensitivity

The co-electrodeposition approach has been widely used to synthesize the transition metal sulfides/oxides because of remarkable performance of the energy storage devices. In this research, cobalt manganese sulfide (CoMnS) binary compounds are synthesized using the co-electrodeposition approach. The main objective is to investigate the optimal number of depositing periods in cyclic voltammetry while maintaining a constant scan rate. The electrodes without binders are produced using a rapid synthesis approach, which involves assessing binary metal sulfide to achieve a significantly enhanced energy storage capacity. Further, the rGO is incorporated into the CoMnS to enhance the electrochemical properties. The CoMnS@rGO electrode showed the specific capacitance (Cs) of 2357 F/g because of the small equivalent series resistance values as determined through electrochemical impedance spectroscopy (EIS) measurement, indicating a higher level of conductivity. The hybrid electrode showed high values of energy and power densities of 50.8 Wh/kg and 3440 W/kg, respectively. Besides, the nanocomposite electrode is used as a chemical sensor and precisely detects the multiple elements. The estimated value of R2 is 0.994 because of the high sensitivity. The hybrid electrode showed a signal-to-noise ratio (S/N) of 5. Furthermore, based on four observations, the comparative standard deviation (RSD) is calculated to be 1.9 %. The device showed high electrochemical glucose detection sensitivity. The nanocomposite-based electrodes provide a platform for designing novel multifunctional devices.

DC current–voltage and impedance spectroscopy characterization of nCdS/pZnTe HJ

This paper describes the electrical and dielectric behavior of the nCdS/pZnTe HJ by current–voltage, capacitance–voltage characteristics, and impedance spectroscopy in a temperature interval 220–350 K. A microcrystalline p-ZnTe layer and n-CdS were grown on glass/ZnO substrate by closed space sublimation method. As frontal contact to CdS, the transparent ZnO and as a back contact to ZnTe, silver conductive paste (Ag) treated at 50 °C in vacuum were used. The current–voltage results of nCdS/pZnTe HJ show a rectifying behavior. The junction ideality factor, barrier height, and series resistance values were extracted from the rectifying curves at different temperatures. The built-in voltage, carrier concentration and depletion width were obtained from the capacitance–voltage measurements. Analysis of the J–V–T and C–V–T characteristics shows that the thermionic emission and recombination current flow mechanisms dominate in the nCdS/pZnTe HJ. The dielectric study reveals that the experimental values of the AC conductivity, dielectric constant, dielectric loss, the imaginary part of the electric modulus are found to be very sensitive to frequency and temperature. The dielectric constant and dielectric loss are observed to be high at the low frequency region. The increase in the values of electric modulus with the frequency implies an increase in the interfacial polarization at the interface of nCdS/pZnTe HJ. Jonscher’s universal power law shows that with increasing frequency, AC conductivity increased. The results conductivity show that the ionic conductivity and interfacial polarization are the main parameters affecting the dielectric properties of the device when the temperature changes.

Photosensitive properties of Schottky type photodiodes prepared by spin coating of isoniazid Schiff base thin film on p-Si

In this study, a layer of isonicotinohydrazide and pyrene-based Schiff base (PyMIs) was formed on the front side of a p-Si semiconductor using the spin coating method, and an Al/PyMIs/p-Si/Al diode was fabricated. The I-V characteristics of the fabricated diode were measured under dark and from 20 to 100 mW/cm2 illumination intensities for both forward and reverse bias. Diode parameters, including saturation current (\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${I}_{0}$$\\end{document}), ideality factor (n), and barrier height (\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\varphi }_{b}$$\\end{document}) were investigated for all measurements based on thermionic emission theory. The values n changed from 2.51 to 2.05, and the \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\varphi }_{b}$$\\end{document} changed from 0.77 eV to 0.86 eV as light intensity increased from dark to 100 mW/cm2. The series resistance (\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${R}_{s}$$\\end{document}) values of the diode were investigated using the modified Norde’s function and Cheung’s functions. An analysis of the forward \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$log\\left( I \\right) - log\\left( V \\right)$$\\end{document} plot of Al/PyMIs/p-Si (MOmS)-type diode specified the carrier transport domination by ohmic conduction in the lower bias regions, by the space-charge-limited current (SCLC) at medium bias regions and the trap-charge limit current (TCLC) transport mechanism at higher bias regions. The fabricated diode exhibited typical photodiode behavior with reverse current values increasing from 9.13 × 10− 6 A to 1.05 × 10− 4 A, respectively. Furthermore, \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$I-V$$\\end{document} characteristics illuminated from 20 to 100 mW/cm2 were also studied, and they indicated that the Al/PyMIs/p-Si diode could operate in a photovoltaic regime.

Optimal Evaluation of Photovoltaic Cells Parameters Using Euclidean Distance Calculations

The relationship between current and voltage describes the features and characteristics of the photovoltaic (PV) cells. This relationship mainly depends on the equivalent circuit parameters of the PV cell model. Accurate estimation of these parameters is crucial for analyzing the performance of PV systems. This paper proposes a simple and efficient method to estimate the equivalent circuit parameters of the PV cells/modules. The main concept of the proposed method is to optimize the PV series resistance value using Euclidean distance calculations in such a way to get the corresponding best maximum power conditions. Various assessments have been employed in this paper to confirm the validity of the presented approach. Those include analyzing different commercial PV modules, experimental data, irradiance and temperature variations, and comparison with other reported algorithms. When compared with experimental data at standard test conditions, the mean absolute current and power differences are 0.0329 A and 0.6339 W, respectively. Furthermore, the mean absolute differences at normal operating cell temperature are 0.0120 A and 0.1412 W. The results have shown that the proposed method has confirmed its effectiveness in predicting the PV cell equivalent circuit characteristics for any PV cells/modules using only data available from the manufacturer’s datasheet.

Illumination dependent electrical, photosensitivity and photodetectivity properties of Au/SiO2/n-Si structures: optoelectronic situations

Abstract This study aims to examine the electrical, photosensitivity (S), photo-response (R), and photo-detectivity (D*) properties of Au/SiO2/n-type Si structures under different illumination intensities. The illumination-dependent properties of the Au/SiO2/n-type Si structure with SiO2 interlayer were obtained using current–voltage (I-V) characteristics. The ideality factors (n) and barrier heights (Φbo) values of Au/SiO2/n-type Si structures were obtained and compared from forward and reverse bias current–voltage (I-V) measurements at room temperature. Also, barrier heights (Φbo) and series resistance (R S ) values obtained from Norde method were compared with the values obtained from TE theory. It was observed that ideality factor and barrier height values obtained from forward bias region are higher than the values reverse bias. This means that the linearity or rectification feature in the reverse bias region is better than the forward bias region. Furthermore, photodiode values such as photo response (R), photosensitivity (S) and photodetectivity (D*) of Au/SiO2/n type Si structures were also examined depending on the light intensity. Consequently, the experimental results showed that the increase in reverse current with increasing light indicates that the Au/SiO2/n-type Si structures can be used in semiconductor technology as a photodiode, detector or sensor.

Effect of 1 wt% Dimethyl Sulfoxide on the Electrical and Photovoltaic Parameters of Schottky Diodes and Organic Solar Cells Based on PEDOT:PSS

Herein, the electrical conductivity of poly(3,4‐ethylenedioxythiophene)–poly(styrenesulfonate) (PEDOT:PSS) polymer is improved by adding dimethyl sulfoxide (DMSO) and electrical characterization of the obtained Schottky diode and organic solar cell (OSC) devices are performed from I–V measurements under the light and dark conditions. The scanning electron microscope images of the poly(3‐hexylthiophene):[6,6]‐phenylC61‐butyric acid methylester active layer and PEDOT:PSS layer are obtained. The series resistance (Rs), barrier height (Фb), and ideality factor (n) parameters are obtained from different techniques as a function of light and dark conditions. Furthermore, photovoltaic parameters are calculated for n‐Si/PEDOT:PSS/Au device without DMSO doping and with DMSO doping as a parameter of the light condition and the interface state densities of these devices are obtained for light and dark conditions. DMSO organic solvent improves the short‐circuit current density (Isc), power convert efficiency (or η), open circuit‐voltage (Voc), shunt resistance (Rsh), and series resistance (Rs) values of OSCs. In summary, DMSO solvent rearranges the conductive of PEDOT:PSS, decreases the work function of this conductive polymer (≈5 eV), decreases energy loss in the charge transportation, and increases photovoltaic parameters of Schottky barrier diode and OSC devices.

A generalized mathematical modeling and performance analysis of GaAs, m-Si and Ge single - junction solar PV cells

Earlier theoretical approaches have analyzed the performance of semiconductor materials for the influence of temperature and band gap which is implemented in solar photovoltaic systems. This paper investigates the detailed mathematical analysis of single junction semiconductor materials such as Gallium Arsenide (GaAs), mono-crystalline Silicon (m-Si) and Germanium (Ge) solar cells parameters namely, Band gap (Eg), reverse saturation current (Io), shunt resistance (Rsh), Short circuit current (Isc), open circuit voltage (Voc), Fill factor (FF), Maximum Power (Pmax) and Efficiency (Ƞ) for temperature ranging from 273K (≈0°C) to 373K (≈100°C). The optimized cell parameters values are obtained under Air Mass 1.5 Global spectrum (Area = 100cm2 and Irradiance = 100 mW/cm2 for the semiconductor materials (GaAs, m-Si and Ge)) at 300K (≈25°C) are compared to identify the higher efficiency and open circuit voltage. Among the semiconductor materials, the single junction GaAs compound semiconductor material is identified with better efficiency and optimized open circuit voltage. A generalized mathematical model of semiconductor materials is developed using single diode equivalent circuit model under SIMULINK platform and it is used to observe the effect of different temperature, irradiance levels, series resistance and shunt resistance values on the performance of solar cells. The discussion is extended for a 2KW PV array for the semiconductor materials (GaAs, m-Si and Ge) under different temperature and irradiance levels. Evaluating the performance of a PV array, rather than individual cells, provides a more comprehensive understanding of how the chosen semiconductor materials function as part of a larger solar energy system.

Electrical Characteristics of Cadmium Sulfide/4-Amino-2-Methyl-Quinoline Heterojunction Structure

We fabricated a heterojunction structure composed of n-CdS and p-C10H10N2 films. The CdS film was prepared using the CBD method, while the C10H10N2 film was prepared using the spin coating method. Later, we performed the current-voltage (I-V) measurement of this PN diode which we made using Keithley 2400 sourcemeter. As can be seen from the logI-V diagram, this heterojunction structure exhibits rectifying properties. Using traditional methods, an ideality factor (n) of 1.93 and a barrier height value (Φb) of 0.79 eV were determined. An ideality factor of more than one indicates non-ideal I-V behavior in the CdS/C10H10N2 heterojunction diode formed. The interface layer, interface states and series resistance are some of the causes of this deviation. Moreover, Cheung's functions and a modified Norde function were used to determine the diode parameters, such as ideality factor, barrier height, and series resistance. With the Cheung method, n=4.33, series resistance (RS)=168.65 kΩ and Φb=0.62 eV were found. Additionally, RS=686.08 kΩ and Φb=0.78 eV were found by the Norde method. Consistent barrier height values were found in all methods through comparison, suggesting compatibility. However, it was discovered that the series resistance values yielded by the Norde function exceeded those obtained by the Cheung functions.

LIFT metallization as an alternative to screen-printing for silicon heterojunction solar cells

The electrical characteristics of solar cells are significantly influenced by the metallization process, making it a crucial step. Screen printing is the standard metallization technique, but there is an increasing interest in the development of methods that allow more versatility, higher process control, and a more efficient use of the expensive metallic pastes used. We focus here on the comparison between the standard screen-printing method, and Light-Induced Forward-Transfer (LIFT), a non-contact, very precise technique, able to transfer volumes down to picolitres. The high flexibility, using free-form designs that do not depend on any mask or physical support, and the efficient use of the metallic paste with almost no waste, are other characteristics that point out LIFT as a very promising alternative. In this paper we include the electric characterization of contacts, and solar silicon heterojunction (SHJ) cells metalized with both techniques. The results show a slightly better efficiency for the screen-printed cells, but good series resistance and fill factor values imply that LIFT is a promising alternative for device metallization.

The Effects of Surface Oxidation and H-Termination Processes Applied to Si Using Electrolytic Hydrogen Peroxide Solution to The Produced Cu/p-Si Schottky Contact Parameters

By using electrolytic hydrogen peroxide (H2O2) solution, oxidation and H-termination processes were applied to the p-Si crystal surface, which will be used for Cu/p-Si Schottky contact production, in a selective and controlled manner. Before the oxidation and H-termination processes, the p-Si(100) wafer used in this study was subjected to conventional chemical cleaning, and ohmic contact was made using pure aluminum (99.99%) metal on its back surface. The p-Si/Al with ohmic back contact was divided into three parts. A rectifying contact was immediately made to the front surface of one of them by using pure copper (99.98%) metal and called the REF (Reference) sample. The front surface of one of the remaining two p-Si/Al parts was oxidized, and the front surface of the other was H-Terminated. Rectifier contacts were made for both using pure copper (99.98%) metal and were named MIS (metal-insulator-semiconductor) and SP (surface passivated), respectively. Current-voltage (I-V) measurements of Schottky diodes of REF, MIS, and SP samples were performed at room temperature and in the dark. From the obtained data, the ideality factor (n), barrier height (Fbo), and series resistance (Rs) values of the samples were determined. As a result of the investigations, it was observed that the surface oxidation and H-Termination processes caused a decrease in the rectification factor and Fbo values of MIS and SP samples. These interesting situations were interpreted by the double-layer theory, which Bardeen predicted could exist on the surface of a semiconductor crystal and contribute to its work function.

Alloy/Perovskite Compounds Modified by Plasma Treatment and their Role in Enhancing the Capacitance of Sustainable Graphene Supercapacitors

AbstractGraphene electrodes were firstly printed on recycled single‐use‐packets. Later, the Ni50Mn35In15 (NMI) alloy or Ca2.9Nd0.1Co3.9Cu0.1O9, (CNCCO) misfit perovskite was deposited on the graphene electrodes to enhance their capacitive performance. Next, flexible supercapacitors (SCs) were assembled by using such electrodes. The SCs made with NMI and CNCCO powders were named as GNMI‐SC, and GCNCCO‐SC, respectively. Those ones produced capacitances/energy‐densities of 761.8 F g−1/152.6 Wh kg−1 and 207.7 F g−1/41.6 Wh kg−1, respectively. Subsequently, a mixture 1 : 1 of NMI and CNCCO powders was melted/coalesced at 1700 °C by using a plasma treatment in argon atmosphere and obtained in this way a NMI/CNCCO composite powder. The SC made with this last composite generated a capacitance/energy‐density of 1235.2 F g−1/247.3 Wh kg−1. Those last values are 62–500 % higher than these for the GNMI‐SC, and GCNCCO‐SC devices. Other benefits obtained after the introduction of the NMI/CNCCO powders into the SCs were: 1) the formation of additional Cu2+, Mn4+, Nd2+ and In3+ species, which enhanced the capacitance; 2) the capacitance retention was maintained above 93 % after 500 cycles of charge discharge; and 3) the lowest values of series and charge transfer resistances were obtained, which favored the ion diffusion/storage in the SC electrodes.

New design and optimization of half-tandem quantum dot solar cell: Over 30% power conversion efficiency using nanostructure oriented core-shell

We achieve 30.64% power conversion efficiency (PCE) by comprehensive design and optimization of half-tandem quantum dot (QD) solar cell using nanostructure-oriented core-shell to improve open circuit voltage (Voc) in QD solar cell (QDSC) for first time. In this study, we have used coupling of optical and electrical equations to calculate solar cell parameters. The aim of this study was to optimize the reference structure including PbS quantum dots (PbS-QDs) treated with tetrabutylammonium iodide (PbS-TBAI), Magnesium Zinc Oxide (MgZnO) and PbS ethanedithiol (PbS-EDT) for active layer (AL), electron transport layer (ETL) and hole transport layer (HTL) respectively. At first, the structure was enhanced into half-tandem solar cell by adding Molybdenum Ditelluride (MoTe2) as the second absorber layer to cover the infrared region. Furthermore, the structure was optimized in four steps: (i) adding a Spiro-OMeTAD layer to reduce the series resistance (Rs) and prevent electrons from entering aluminum metal contact, (ii) adding a core-shell (CFTS – SnS) nanostructure, (iii) optimizing ETL, and (iv) investigating the effect of core-shell nanostructure angle. As a final result, the values of short circuit current (Jsc), Voc, PCE, fill factor (FF) and series resistance were obtained 25.25 mA/cm2, 1.49 V, 30.64 %, 0.78 and 2.8 Ω/cm2, respectively.