ZnSe Buffer Layer Research Articles

Efficiency enhancement of novel ITO/ZnSe/CNTs thin film solar cell

This study presents a novel photovoltaic cell design utilizing a layered structure of Indium Tin Oxide (ITO), Zinc Selenide (ZnSe), and Carbon Nanotubes (CNTs) for enhanced solar energy conversion. We employed the Solar Cell Capacity Simulator (SCAPS-1D) to model and optimize the device under AM 1.5 spectrum conditions. Our simulations systematically investigated the influence of key parameters including layer thicknesses, doping concentrations, temperature, back contact work function, and parasitic resistances on cell performance. The optimized structure demonstrated a theoretical power conversion efficiency of 29.91%, with an open-circuit voltage (Voc) of 799 mV, a short-circuit current density (Jsc) of 43.49 mA/cm², and a fill factor (FF) of 86.02%. These promising results are attributed to the synergistic combination of CNTs' broad spectral absorption, ZnSe's effective charge separation, and optimized layer properties. We found that the CNT absorber layer's doping concentration significantly impacted cell performance, with an optimal value of 10¹⁷ cm⁻³. The ZnSe buffer layer thickness showed minimal effect on efficiency within the studied range. Temperature increases from 300 K to 400 K led to a significant efficiency drop from 33.97% to 24.65%, primarily due to Voc reduction. While these results represent idealized conditions and upper theoretical limits, they provide valuable insights for the potential of CNT-based solar cells. This study offers a roadmap for future experimental work in high-efficiency thin-film photovoltaics, highlighting the promise of novel material combinations and the importance of device architecture optimization.

Investigation of suitable buffer layer for PbS-TBAI/PbS-EDT colloidal quantum dot solar cell using SCAPS-1D

Colloidal quantum dots (CQD) are emerging third-generation photovoltaic technologies because of their ability to link a wider range of the light spectrum compared to those of perovskite, crystalline, and copper indium gallium selenide (CIGS) solar cells. In this work, a Lead Sulphide (PbS) CQD solar cell architecture with Ag2S, CdS, ZnSe and ZnS buffer layer is presented. The device consisting of PbS-tetrabutyle ammonium iodide (PbS-TBAI) as an absorber layer, PbS-1,2-ethanedithiol (PbS-EDT) as a hole transport layer (HTL), TiO2 as an electron transport layer (ETL), and fluorine tin oxide (FTO) as an oxide layer. The electrical performances of the solar cells were simulated using SCAPS-1D while taking into account different buffer layers with increasing bandgap values. With ZnS acting as a buffer layer, the computational modelling and analysis of architectural PbS CQD solar cell result in an efficiency of 17.12%. Additionally, the parameters of the solar cell have been studied to be affected by the thickness and bandgap of the absorber and HTL layers, the effect of acceptor concentration with various buffer layers, the impact of temperature, the effect of HTL doping density, and the effect of absorber layer defect density. This study can serve as a guide for future PbS CQD solar cells.

Simulation and performance analysis of CdTe thin film solar cell using different Cd-free zinc chalcogenide-based buffer layers

In this study, the performance of a Cadmium Telluride (CdTe) thin-film solar cell was evaluated with various buffer layers (CdS, ZnSe, ZnO, ZnS) using the Silvaco-Atlas semiconductor device simulator. The impact of these buffer layers on the functionality of the CdTe solar cell was scrutinized at a temperature of 300 K under standard AM1.5G illumination. Initially, the modeling and simulation results of CdS/CdTe solar cell were examined, in comparison with the experimental and simulation results previously reported, to validate our reference structure and to explore its performance. The baseline CdS/CdTe solar cell, serving as a benchmark, yielded a conversion efficiency of 22.14 %. Then we attempted to identify an environmentally friendly alternative buffer layer for the CdTe thin film solar cell by substituting CdS with various Cd-free zinc chalcogenide-based materials (Zn(O,S,Se)) to boost efficiency. By trimming the layer thickness to approximately 0.01 μm, conversion efficiencies of 23.04 %, 23.13 % and 24.48 % were attained for the ZnO, ZnSe, and ZnS buffer layers, respectively. In order to investigate the performance of each proposed structure, thickness and doping density of the absorber and buffer layer were varied. Best efficiency around 25.23 % and 25.04 % are achieved for the optimized solar cells for ZnS and ZnSe buffer layer, respectively. As a result, ZnS and ZnSe are promising materials can be used as an alternative to the commonly used CdS buffer layer in CdTe solar cell. The influence of the operating temperature on solar cell performance was also investigated.

Design and numerical analysis of CIGS-based solar cell with V2O5 as the BSF layer to enhance photovoltaic performance

Copper indium gallium selenide (CIGS)-based solar cells have exhibited greater performance than the ones utilizing cadmium telluride (CdTe) or hydrogenated amorphous silicon (a-Si: H) as the absorber. CIGS-based devices are more efficient, considering their device performance, environmentally benign nature, and reduced cost. In this article, we proposed a potential CIGS-absorber-based solar cell with an FTO/ZnSe/CIGS/V2O5/Cu heterostructure, with a V2O5 back-surface field (BSF) layer, SnO2:F (FTO) window layer, and ZnSe buffer layer. Using the solar cell capacitance simulator one-dimensional simulation software, the effects of the presence of the BSF layer, the thickness, bulk defect density, and acceptor density of the absorber layer, buffer layer thickness, interfacial defect density, device resistance, and operating temperature on the open-circuit voltage, short-circuit current, fill factor, and efficiency, as well as on the quantum efficiency and recombination and generation rate, of the device have been explored in detail. The simulation results revealed that only a 1 μm-thick-CIGS absorber layer with V2O5 BSF and ZnSe buffer layers in this structure offers an outstanding efficiency of 31.86% with a VOC of ∼0.9 V. Thus, these outcomes of the CIGS-based proposed heterostructure provide an insightful pathway for fabricating high-efficiency solar cells with performance more promising than the previously reported conventional designs.

24% Efficient, Simple ZnSe/Sb2Se3 Heterojunction Solar Cell: An Analysis of PV Characteristics and Defects.

In this work, a new wide-band-gap n-type buffer layer, ZnSe, has been proposed and investigated for an antimony selenide (Sb2Se3)-based thin-film solar cell. The study aims to boost the Sb2Se3-based solar cell's performance by incorporating a cheap, widely accessible ZnSe buffer layer into the solar cell structure as a replacement for the CdS layer. Solar Cell Capacitance Simulator in One Dimension (SCAPS-1D) simulation software is used to thoroughly analyze the photovoltaic parameters of the heterojunction structure ZnSe/Sb2Se3. It includes open circuit voltage (V OC), short-circuit current density (J SC), fill factor (FF), power conversion efficiency (PCE), and external quantum efficiency (EQE). The absorber layer (Sb2Se3) thickness is adjusted from 0.5 to 3.0 μm to perfect the device. In addition, the influence of cell resistances, radiative recombination coefficient, acceptor and donor defect concentration in the Sb2Se3 layer, and interface defects of the ZnSe/Sb2Se3 layer on overall device performance are investigated. The ZnSe buffer layer and the Sb2Se3 absorber layer are designed to have optimal thicknesses of 100 nm and 1.5 μm, respectively. The proposed device's efficiency with optimized parameters is calculated to be 24%. According to the simulation results, it is possible to build Sb2Se3-based thin-film solar devices at a low cost and with high efficiency by incorporating ZnSe as an electron transport layer.

Numerical Simulation of Non-toxic ZnSe Buffer Layer to Enhance Sb2S3 Solar Cell Efficiency Using SCAPS-1D Software

The use of renewable energy, especially solar photovoltaic, has grown more and more necessary in the context of the diversification of the use of natural resources. Sb2S3 is emerged as an attractive candidate for today's thin-film solar cells due to its band gap of 1.65 eV and high absorption coefficient greater than 105 cm-1. Cadmium Sulfide is the most commonly used buffer layer material in thin film solar cells, but cadmium is a metal that causes severe toxicity in humans and the environment. This article tried to avoid cadmium for solar cell generation. This paper presents the findings of a computer simulation analysis of a thin film solar cell based on a p-type Sb2S3 absorber layer and an n-type ZnSe buffer layer in a structure of (Sb2S3/ZnSe/i-ZnO/ZnO: Al) utilizing simulation software (SCAPS-1D). The simulation included detailed configuration optimization for the thickness of the absorber layer, buffer layer, defect density, temperature, and series-shunt resistance. In this work, the Efficiency (η), Fill Factor (FF), Open-circuit Voltage (Voc), and short-circuit current (Jsc) have been measured by varying thickness of absorber layer in the range of 0.5µm to 4 µm and by varying thickness of buffer layer in the range of 0.05 µm to 0.1µm. The optimized solar cell shows an efficiency of 20.03% when the absorber layer thickness is 4µm and the buffer layer thickness is 0.08µm.

Analysis of different buffer layers on CuO based solar cells using SCAPS-1D

We have used SCAPS-1D to do simulations on CuO based solar cells using ZnO, TiO2, CdS and ZnSe as buffer layers. The solar cell characteristics are analysed by varying different material properties. The CuO/ZnO based solar cell showed highest efficiency ~20%. The interface defect however impacts the efficiency of this solar cell significantly. The interface defect and buffer layer thickness has shown little impact on the TiO2 and ZnSe buffer layer based solar cell. Further, we have optimized the impact of absorber layer thickness, carrier concentration and absorber defect as well. The effect of buffer layer thickness and electron affinity has also been investigated. Further, we have tried to understand the effect of temperature on the performance of these solar cells. The increase in temperature has resulted in decreased efficiency attributing to increased recombination rate.

Exploring epitaxial growth of ZnTe thin films on Si substrates

Epitaxial growth of ZnTe on Si occurred via matching of eight ZnTe (111) planes with nine Si (111) planes. However, the stacking faults existed in the ZnTe/Si system due to the release of strain energy in initial growth. To further improve ZnTe epilayer quality, different architectures containing ZnTe nucleation layer, or ZnSe buffer layer were grown on Si substrates. The fewer defects can be found across the interfaces for ZnTe/ZnSe with 12/13 or 13/14 matching and ZnSe/Si with 21/22 or 21/23 matching of major planes. Only {111}-oriented domain formed in the ZnTe epilayer for the large-lattice-mismatched samples. The improved ZnTe (111) epitaxial thin films with single domain exhibit the narrowest FWHM of ∼180 arc sec with a dislocation density of 5.14 × 107 cm −2. Extra half-planar arrays formed at the interfaces of ZnTe/ZnSe, ZnSe/Si were clearly visible through inverse fast Fourier transformation images. Moreover, the fully relaxed ZnTe epilayer with the most balanced residual stress was obtained in the X and Y directions.

High Performance for Cu(In,Ga)Se<sub>2</sub> Quaternary System-Based Solar Cells with Alternative Buffer Layers

In this study, the authors investigated the performance of different buffer layers through the electrical parameters such as Jsc, Voc, QE and η of the quaternary system Cu(In,Ga)Se2 solar cells. The performance of Cu(In,Ga)Se2solar cells has been modeled and numerically simulated by using the SCAPS- 1D device simulation tool. The cells with a ZnSe, Zn(O,S) and (Zn,Mg)O buffer layers were compared with the reference CdS buffer layer. The investigation of ZnSe, Zn(O, S) and (Zn,Mg)O-based cells to substitute the traditional CdS in the future shows that the ZnSe-buffer layer is a potential material to replace CdS, which revealed the best efficiency of 20.76%, the other electrical parameters are: JSC = 34.6 mA/cm2, VOC = 0.76 V and FF = 79.6%. The losses as a function of the temperature are estimated at 0.1%/K, among all kinds of buffer layers studied. We have also shown that the use of a high band-gap buffer layer is necessary to obtain a better short-circuit current density JSC. From our results, we note that the chalcogenide solar cells with Zn-based alternative buffer layer have almost the same stability thatthe traditional CdS buffer layer solar cells have.

Numerical Modelling Analysis for Carrier Concentration Level Optimization of CdTe Heterojunction Thin Film–Based Solar Cell with Different Non–Toxic Metal Chalcogenide Buffer Layers Replacements: Using SCAPS–1D Software

Cadmium telluride (CdTe), a metallic dichalcogenide material, was utilized as an absorber layer for thin film–based solar cells with appropriate configurations and the SCAPS–1D structures program was used to evaluate the results. In both known and developing thin film photovoltaic systems, a CdS thin–film buffer layer is frequently employed as a traditional n–type heterojunction partner. In this study, numerical simulation was used to determine a suitable non–toxic material for the buffer layer that can be used instead of CdS, among various types of buffer layers (ZnSe, ZnO, ZnS and In2S3) and carrier concentrations for the absorber layer (NA) and buffer layer (ND) were varied to determine the optimal simulation parameters. Carrier concentrations (NA from 2 × 1012 cm−3 to 2 × 1017 cm−3 and ND from 1 × 1016 cm−3 to 1 × 1022 cm−3) differed. The results showed that the use of CdS as a buffer–layer–based CdTe absorber layer for solar cell had the highest efficiency (%) of 17.43%. Furthermore, high conversion efficiencies of 17.42% and 16.27% were for the ZnSe and ZnO-based buffer layers, respectively. As a result, ZnO and ZnSe are potential candidates for replacing the CdS buffer layer in thin–film solar cells. Here, the absorber (CdTe) and buffer (ZnSe) layers were chosen to improve the efficiency by finding the optimal density of the carrier concentration (acceptor and donor). The simulation findings above provide helpful recommendations for fabricating high–efficiency metal oxide–based solar cells in the lab.

Improved growth quality of epitaxial ZnTe thin films on Si (111) wafer with ZnSe buffer layer

To achieve high-quality and low-cost ZnTe epitaxial films, a low-temperature (LT, 200 °C) ZnSe buffer layer with a thickness of 5 nm was grown on Si (111) wafers prior to the epitaxy of ZnTe layers by molecular beam epitaxy. Reflection high-energy electron diffraction patterns reveal that ZnTe epilayers grown at 335 °C with a thickness of 100 nm on the LT-ZnSe buffer layer present a completely two-dimensional growth mode. Film surfaces present smooth and flat morphology with the lowest surface roughness of ∼2.2 nm at a Te/Zn beam equivalent pressure ratio of 1.6. X-ray diffraction θ-2θ scanning indicates that the out-of-plane structure of ZnTe films is highly preferred with the (111) growth orientation of ZnSe/Si. X-ray diffraction φ scanning further confirms that the in-plane structure of ZnTe epilayer is also a single-crystal orientation growth. Thus, high-quality ZnTe (111) single-crystal epilayer with the lowest full-width at half-maximum of ∼200 arc sec and the smallest dislocation density of ∼1.12 × 108 cm−2 was grown on Si (111) wafers. In addition, the ZnSe buffer layer could alleviate the residual stress effectively for the heteroepitaxy of Si wafers. The most balanced residual stress for ZnTe/ZnSe/Si with σx of ∼96.5 MPa and σy of ∼94.2 MPa was obtained, which is essential for achieving high-performance and good mechanical properties of ZnTe-based devices.

Numerical Simulation for Optimization of ZnTe-Based Thin-Film Heterojunction Solar Cells with Different Metal Chalcogenide Buffer Layers Replacements: SCAPS-1D Simulation Program

In this study, Zinc Telluride (ZnTe)-based solar cells, which are metallic dichalcogenide materials, are used as a solar cell absorbent with the formation appropriate for solar cell use. The data has been analyzed by SCAPS-1D structures software. The replacement of Cadmium Sulfide CdS (buffer) layer by other green and save suitable materials has been investigated. The substituted buffer layers have been ZnSe, ZnS, CdSe, and In2S3. The higher device performance efficiency parameters have been found out when using CdS and ZnSe as buffer layers. SCAPS-1D shows that the optimal p-n junction device eff]iciency parameters have been achieved when the ZnTe (absorber) layer thickness is between 1200-1500 nm, while the ZnSe (buffer) layer thickness is between 20-60 nm, and the thickness of ZnO:Al (window) layer is 25 nm. The results of the simulation provide important hints that may enhance the performance of the cell with empirical studies useful in practical implementation.

An emerging high performance photovoltaic device with mechanical stability constants of hybrid (HC(NH2)2PbI3) perovskite

Here in, we present the extensive analysis of the parameters associated with structural, electronic, optical and mechanical properties of HC(NH2)2PbI3 or FAPbI3 (FA = Formamidinium) by using full potential linearized augmented plane wave method (FP-LAPW) within framework on the density functional theory. The band structure shows that FAPbI3 has a direct band gap (1.44 eV) at the symmetry point R (0.5, 0.5, 0.5) and are in best agreement with experimental data. The strong hybridization of s orbitals of Pb and p orbitals of I in valance band plays an important role in the structural stability. From the mechanical constants, we have observed that this is ductile in nature and perfect use for photovoltaic applications. Further, FAPbI3 photovoltaic device has been prepared and device parameters have discussed for ZnO, ZnS, ZnSe, ZnTe and CdS buffer layers. The calculated results for FAPbI3 thin layer solar cell show maximum efficiency (20.48% and 20.77%) with ZnS and CdS buffer layers respectively. The proposed results further validate the prospects of methylammonium (MA) free perovskites and it would be persistent and consistent with the flexible substratum. These are the main features of commercialization perovskite solar cells. Thus, promoting the evolution of cubic FAPbI3, for achieving high performance-based optoelectronic devices and will pave a new path in solar cell industry.

Growth of GaAs on single-crystal layered-2D Bi2Se3

Abstract This work demonstrates the successful growth of cubic GaAs (111) on single-crystal 2D layered Bi2Se3 (0001) substrates achieved using a cubic ZnSe buffer layer. This growth sequence was chosen based upon observed reactions between Bi2Se3 (0001) substrates and both Ga and Zn. For the conditions used in our MOCVD reactor, triethylgallium (TEGa) interacts strongly with Bi2Se3 to form Ga2Se3, which can disrupt the nucleation and growth of GaAs. Therefore, a buffer layer is needed which prevents Ga–Bi2Se3 interactions while simultaneously providing a suitable growth surface for GaAs. ZnSe was chosen because it is lattice-matched to GaAs, and can be created by annealing the Bi2Se3 under a diethylzinc (DEZn) flux. A sample utilizing this growth sequence has been grown, characterized and exfoliated as a possible pathway toward reducing the substrate cost for III-V devices such as solar cells.

High-efficiency CIGS solar cell by optimization of doping concentration, thickness and energy band gap

In this paper, the performance of copper-indium-gallium-diselenide Cu(In,Ga)Se2 solar cell, with ZnO window layer, ZnSe buffer layer, CIGS absorber layer and InGaP reflector layer was studied. The study was performed using the TCAD Silvaco simulator. The effects of grading the band gap of CIGS absorber layer, the various thicknesses and doping concentrations of different layers have been investigated. By optimizing the solar cell structure, we have obtained a maximum open circuit voltage of 0.91901 V, a short circuit current density of 39.89910 mA/cm2, a fill factor (FF) of 86.67040% and an efficiency of 31.78% which is much higher than the values for similar CIGS solar cells reported so far.

High Efficiency CdS/CdSe Quantum Dot Sensitized Solar Cells with Two ZnSe Layers.

CdS/CdSe quantum dot sensitized solar cells (QDSCs) have been intensively investigated; however, most of the reported power conversion efficiency (PCE) is still lower than 7% due to serious charge recombination and a low loading amount of QDs. Therefore, suppressing charge recombination and enhancing light absorption are required to improve the performance of QDSCs. The present study demonstrated successful design and fabrication of QDSCs with a high efficiency of 7.24% based on CdS/CdSe QDs with two ZnSe layers inserted at the interfaces between QDs and TiO2 and electrolyte. The effects of two ZnSe layers on the performance of the QDSCs were systematically investigated. The results indicated that the inner ZnSe buffer layer located between QDs and TiO2 serves as a seed layer to enhance the subsequent deposition of CdS/CdSe QDs, which leads to higher loading amount and covering ratio of QDs on the TiO2 photoanode. The outer ZnSe layer located between QDs and electrolyte behaves as an effective passivation layer, which not only reduces the surface charge recombination, but also enhances the light harvesting.

Energy efficiency of a photovoltaic cell based thin films CZTS by SCAPS

In the overall context of the diversification of the use of natural resources, the use of renewable energy including solar photovoltaic has become increasingly indispensable. As such, the development of a new generation of photovoltaic cells based on CuZnSnS4 (CZTS) looks promising. Cu2ZnSnS4 (CZTS) is a new film absorber, with good physical properties (band gap energy 1.4-1.6 eV [01] with a large absorption coefficient over 104 cm-1). Indeed, the performance of these cells exceeded 30% in recent years.In the present paper, our work based on modeling and numerical simulation, we used SCAPS to study the performance of solar cells based on Cu2ZnSnS4 (CZTS) and thus evaluate the electrical efficiency η for typical structures of ZnO / i- ZnO / CdS / CZTS and ITO / ZnO / CdS / CZTS. Furthermore, the influence of the change of CdS by ZnSe buffer layer was treated in this paper.Keywords: solar cell; photovoltaic; thin film Cu2ZnSnS4; simulation; SCAPS

Simulated solar cell device of CuGaSe2 by using CdS, ZnS and ZnSe buffer layers

We have performed ab-initio calculations for the structural, electronic, optical, elastic and thermal properties of the copper gallium chalcopyrite (CuGaSe2). The Full Potential Linearized Augmented Plane Wave (FP-LAPW) method is used to find the equilibrium structural parameters and to compute the full elastic tensors. We have reported electronic and optical properties with the recently developed density functional of Tran and Blaha. Furthermore, optical features such as dielectric functions, refractive indices, extinction coefficient, optical reflectivity, absorption coefficients, optical conductivities, are calculated for photon energies up to 30eV. The thermodynamical properties such as thermal expansion, heat capacity, Debye temperature, entropy and Grüneisen parameter, bulk modulus and hardness are calculated employing the quasi-harmonic Debye model at different temperatures (0–1200K) and pressures (0–8GPa) and the silent results are interpreted. To check the potentiality of CuGaSe2 as future solar cell material, device modeling and simulation studies have been carried out with a variety of buffer layers over CuGaSe2 absorption layer. The band diagram and J/V curves are analyzed and device performance parameters i.e. efficiency, open circuit voltage, short circuit current, quantum efficiency are calculated for CdS, ZnS and ZnSe buffer layers. Simulation results for CuGaSe2 thin layer solar cell show the maximum efficiency (15.8%) with ZnSe as the buffer layer. Most of the investigated parameters are reported for the first time.

Modification of electron states in CdTe absorber due to a buffer layer in CdTe/CdS solar cells

By application of the ac admittance spectroscopy method, the defect state energy distributions were determined in CdTe incorporated in thin film solar cell structures concluded on ZnO, ZnSe, and ZnS buffer layers. Together with the Mott-Schottky analysis, the results revealed a strong modification of the defect density of states and the concentration of the uncompensated acceptors as influenced by the choice of the buffer layer. In the solar cells formed on ZnSe and ZnS, the Fermi level and the energy position of the dominant deep trap levels were observed to shift closer to the midgap of CdTe, suggesting the mid-gap states may act as recombination centers and impact the open-circuit voltage and the fill factor of the solar cells. For the deeper states, the broadening parameter was observed to increase, indicating fluctuations of the charge on a microscopic scale. Such changes can be attributed to the grain-boundary strain and the modification of the charge trapped at the grain-boundary interface states in polycrystalline CdTe.

Metalorganic vapor phase epitaxy of ternary rhombohedral [formula omitted] Se3 solid solutions

We studied the metalorganic vapor phase epitaxy (MOVPE) of (Bi1−xSbx)2Se3 solid solution films with a different Sb content on (001) Al2O3 substrates with thin ZnSe buffer layer in the range of temperatures 250–480°C. As-grown films were studied by atom force and scanning electron microscopy (AFM and SEM), Raman spectroscopy and X-ray diffractometry (XRD) techniques. To determine the elemental composition of the grown films, we used an energy dispersive spectrometer (EDS). The dependencies of the crystal structure of films on the growth temperature and Sb content (0≤x≤1) were explored. At different growth temperatures we obtained the following bismuth compounds: the films grown at the temperature of 370°C or lower consist of the pure Bi phase, whereas we got the Bi4Se3 phase at 380°C, the phase BiSe at 430°C and Bi2Se3 at the temperature of 460°C or above. We found out that at the temperature of 480°C the single-phase films of (Bi1−xSbx)2Se3 with rhombohedral and orthorhombic lattices are realized when x is less than 0.25 and greater than 0.935, respectively. For 0.25<x<0.935 the grown films are composites of rhombohedral and orthorhombic phases. At the temperature of 440°C we obtained films consisting of three rhombohedral phases (Bi1−xSbx)4Se3, (Bi1−xSbx) Se and Bi. The room temperature transport properties of rhombohedral samples were characterized using the Van der Pauw technique.