The CGS and CIGS being promising materials for large scale photovoltaic applications, the effect ... more The CGS and CIGS being promising materials for large scale photovoltaic applications, the effect of temperature on the electrical parameters of a CGS/CIGS tandem solar cell has been investigated in this work. The copper gallium diselenide (CGS) and copper indium gallium diselenide (CIGS) structures as topcell and bottom-cell respectively, were numerically simulated under AM1.5G spectral illumination using the two-dimensional device simulator Silvaco-Atlas. The temperature dependency of the solar cell’s characteristics was investigated in the temperature range from 300 to 400 K at intervals of 20 K. The simulation results show the density current (Jsc) slightly increases whereas the open-circuit voltage (Voc) and fill factor (FF), conversion efficiency () decreases with the increase in temperature. The tandem cell operating temperature efficiency was found to be (– 0.34 %/K), which is slightly higher than that of CGS solar cell (– 0.29 %/K), but markedly better than that of CIGS solar cell (– 0.41 %/K).
The solar spectrum can be divided by tandem solar cells into several subcells that have different... more The solar spectrum can be divided by tandem solar cells into several subcells that have different bandgaps which convert, more effectively, the light into electricity than the single cells. In this study, the simulation of the photovoltaic (PV) characteristics of a CZTS/CZTSe tandem solar cell, based on structures of copper zinc tin sulfide (CZTS) as a top cell and copper zinc tin selenide (CZTSe) as a bottom cell, was accomplished by using SCAPS-1D simulator under AM1.5 illumination. Initially, the simulation of single CZTS and CZTSe solar cells was performed to give efficiency of 14.37 % and 17.87 %, respectively, which are in good agreement with the literature results. Before feeding with filtered spectrum, the simulated PV parameters of the CZTS/CZTSe tandem solar cell are the conversion efficiency (ƞ) of 20.68 % and the shortcircuit current density (Jsc) of 20.205 mA/cm2 of the top and bottom cells with arbitrary normal thicknesses. Furthermore, and in order to reach the matching current, both top and bottom cells have been investigated at different thicknesses for tandem configuration after validation, where the performance of the top and bottom cells is at thicknesses ranged from 0.05-0.5 µm and 0.1-1 µm, respectively. The performance of the tandem solar cell is determined after filtered spectrum feeding and current matching. The Jsc of CZTS/CZTSe tandem solar cell is 20.33 mA/cm2 for 0.255 µm thick of the top, CZTS, cell and 0.8 µm of the bottom, CZTSe, cell. The maximum ƞ of 22.98 % is reached for tandem structure design with open circuit voltage (Voc) enhancing of 1.48 V.
The CGS and CIGS being promising materials for large scale photovoltaic applications, the effect ... more The CGS and CIGS being promising materials for large scale photovoltaic applications, the effect of temperature on the electrical parameters of a CGS/CIGS tandem solar cell has been investigated in this work. The copper gallium diselenide (CGS) and copper indium gallium diselenide (CIGS) structures as topcell and bottom-cell respectively, were numerically simulated under AM1.5G spectral illumination using the two-dimensional device simulator Silvaco-Atlas. The temperature dependency of the solar cell’s characteristics was investigated in the temperature range from 300 to 400 K at intervals of 20 K. The simulation results show the density current (Jsc) slightly increases whereas the open-circuit voltage (Voc) and fill factor (FF), conversion efficiency () decreases with the increase in temperature. The tandem cell operating temperature efficiency was found to be (– 0.34 %/K), which is slightly higher than that of CGS solar cell (– 0.29 %/K), but markedly better than that of CIGS solar cell (– 0.41 %/K).
The solar spectrum can be divided by tandem solar cells into several subcells that have different... more The solar spectrum can be divided by tandem solar cells into several subcells that have different bandgaps which convert, more effectively, the light into electricity than the single cells. In this study, the simulation of the photovoltaic (PV) characteristics of a CZTS/CZTSe tandem solar cell, based on structures of copper zinc tin sulfide (CZTS) as a top cell and copper zinc tin selenide (CZTSe) as a bottom cell, was accomplished by using SCAPS-1D simulator under AM1.5 illumination. Initially, the simulation of single CZTS and CZTSe solar cells was performed to give efficiency of 14.37 % and 17.87 %, respectively, which are in good agreement with the literature results. Before feeding with filtered spectrum, the simulated PV parameters of the CZTS/CZTSe tandem solar cell are the conversion efficiency (ƞ) of 20.68 % and the shortcircuit current density (Jsc) of 20.205 mA/cm2 of the top and bottom cells with arbitrary normal thicknesses. Furthermore, and in order to reach the matching current, both top and bottom cells have been investigated at different thicknesses for tandem configuration after validation, where the performance of the top and bottom cells is at thicknesses ranged from 0.05-0.5 µm and 0.1-1 µm, respectively. The performance of the tandem solar cell is determined after filtered spectrum feeding and current matching. The Jsc of CZTS/CZTSe tandem solar cell is 20.33 mA/cm2 for 0.255 µm thick of the top, CZTS, cell and 0.8 µm of the bottom, CZTSe, cell. The maximum ƞ of 22.98 % is reached for tandem structure design with open circuit voltage (Voc) enhancing of 1.48 V.
Zinc oxide (ZnO) is one of the best transparent conducting oxide (TCO) materials with a wide band... more Zinc oxide (ZnO) is one of the best transparent conducting oxide (TCO) materials with a wide bandgap and good electrical and optical properties. Its low cost, nontoxicity and transparency in the optical region of the electromagnetic spectrum make it very promising candidate for solar cell applications. In this work, zinc acetate precursor was used to grow a ZnO thin film by using sol-gel spin-coating technique. The surface morphological study using scanning electron microscope (SEM) was carried out to confirm the growth pattern and crystal distribution. The optical properties, transmission (T), reflection (R), optical bandgap (Eg), refractive index (n), and extinction coefficient (k) were extracted and investigated to be used in the simulation of ZnO/Cu2O heterostructure solar cell, where ZnO thin film plays a double role: as the TCO window, as well as the emitter of the n-p junction. However, the solar cell showed weak external quantum efficiency (EQE) compared to those prepared by using zinc nitrate and diethyl zinc precursors. TCAD numerical simulation was used to clarify the origin of this weak EQE by taking into account two parameters. The first studied parameter is the root-mean-square interface roughness, RMS, in Haze modeling approach, H, which describes how much of incident light is scattered at the interface. The second studied parameter is the density of defects in the ZnO bulk with continuous distribution of states in its bandgap similar to an amorphous semiconductor made of tail bands and Gaussian distribution deep level bands. Consequently, and by adjusting and investigating the effect of the RMS and the constituents of the bandgap states, we were able to obtain a good agreement between simulated and measured EQE characteristics of the solar cell.
L‟énergie solaire est l‟une des filières très prometteuse comme alternatif aux sources d‟énergie ... more L‟énergie solaire est l‟une des filières très prometteuse comme alternatif aux sources d‟énergie classique. Mais le rendement des panneaux solaires aujourd‟hui sont loin d‟être concluantes pour le choix de cette filière. Le composant de base de cette filière est la cellule solaire. Cette dernière peut être réalisée par différents matériaux semi-conducteurs comme le silicium. Le Silicium monocristallin s‟avère très couteux. Une alternative moins chère est les cellules solaires en couches minces. Les meilleurs compromis rendement-cout sont les filières silicium amorphe (a-Si) et les semiconducteurs II-VI (CdO, CdTe, CdS, ZnO, ZnTe, ZnS…). Les oxydes conducteurs transparent (TCO : Transparent Conducting Oxides) des films minces ont une grande importance dans des applications de dispositifs électroniques. Ils sont basés sur les semiconducteurs II-VI qui sont souvent des oxydes métalliques (ZnO, CdO, MgO...). Ils sont des semiconducteurs de type n avec un gap d‟énergie élevée et il est c...
Transactions on Electrical and Electronic Materials, 2022
Zinc oxide (ZnO) thin films were deposited on glass substrates by using sol–gel spin coating tech... more Zinc oxide (ZnO) thin films were deposited on glass substrates by using sol–gel spin coating technique. Zinc acetate dihydrate and 2-methoxyethanol were used as precursor with different molar concentrations, 0.2 M, 0.3 M and 0.6 M. The effect of precursor concentration on the structural and optical properties, transmission (T), reflection (R), optical bandgap (Eg), Urbach energy (EU), refractive index (n), extinction coefficient (k), single-oscillator energy (E0), dispersion energy (Ed), moments M−1 and M−3, dielectric constant (ε) and optical conductivity (σ), of the ZnO thin films was studied and investigated. Although, the transmittance, slightly, decreased and the reflectance increased, as the molar concentration increased, the measurements showed that all samples have high transparency and low reflectivity in the visible range which make them suitable for solar cells applications. It is also found that, as the molarity increased, the ZnO thin films exhibited lower Eg and EU and higher Ed, M−1 and M−3.
• Fabrication of ZnO film by sol–gel using zinc acetate decomposition • Extraction of the optical... more • Fabrication of ZnO film by sol–gel using zinc acetate decomposition • Extraction of the optical parameters to be used in modeling a ZnO/p-Si solar. • This is to elucidate the solar cell weak performance • Defects in the ZnO bulk and the surface recombination velocity in the ZnO/p-Si interface were responsible. • The simulation led to comparable values between simulation and measurement of J-V characteristics.
This study is a numerical simulation obtained by using Silvaco Atlas software to investigate the ... more This study is a numerical simulation obtained by using Silvaco Atlas software to investigate the effect of different types of dielectric layers, inserted between the channel and the gate, on the performance and reliability of an a-ITZO TFT.
Cadmium oxide (CdO) is a semiconductor with promising electrical and optical properties. Pure CdO... more Cadmium oxide (CdO) is a semiconductor with promising electrical and optical properties. Pure CdO is an n-type degenerate semiconductor and is almost entirely transparent in the optical region of the electromagnetic spectrum. Thus, the interest in its study as a possible device for photo detectors and solar cells has increased significantly. However real solar cells, based on an n-CdO/p-Si heterostructures, show poor photovoltaic performance [1]. In this work numerical simulation is used to elucidate this poor performance. Figure 1 shows measured photovoltaic performance of an n-CdO/p-Si heterostructures [1]. We have simulated the same structure by considering two cases. The first is that CdO is a perfect material. The second models CdO as a semiconductor with continuous distribution of states in its band gap similar to an amorphous semiconductor. The density of states model used here is composed of four bands: two tail bands (a donor-like g_TD (E) and an acceptor-like g_TA (E)) and...
Tile: DESIGN OF II-VI THIN FILM SOLAR CELLS A b s t r a c t CdTe thin films are used as absorber ... more Tile: DESIGN OF II-VI THIN FILM SOLAR CELLS A b s t r a c t CdTe thin films are used as absorber layer in CdS/CdTe solar cells. The microstructure of this layer plays a fundamental role in photovoltaic conversion potential where their conversion efficiency is in the range of 18–24% with low-cost manufacturability. In this work, we study the effect of the thickness of the CdTe absorber layer on the efficiency of a thin-film CdS/CdTe heterostructure to find their best combination for improvement of the solar cell efficiency. To explore the possibility of ultra thin and high efficiency CdS/CdTe solar cell, the thickness CdTe absorber layer was increased and found that 4 μm thin CdTe layer showed reasonable efficiency.
Over the last two decades, the electromagnetic radiation is becoming the fourth public pollution ... more Over the last two decades, the electromagnetic radiation is becoming the fourth public pollution in addition to the noise, water and air pollution. Here, we had studied the structure and the electromagnetic properties of machine-knitted fabric coated with silver by means of microscopy and shielding effectiveness in the open space. The silver-plated polyester fabric showed a different shielding effectiveness of electromagnetic wave in the open space compared with enclosed space. The value of SE had closed relation with transmitting and receiving distance except the theory factor. When the frequency dropped below 900 MHz, the value SE usually became negative.
Dependences of the open-circuit voltage, short-circuit current, fill factor, and efficiency of a ... more Dependences of the open-circuit voltage, short-circuit current, fill factor, and efficiency of a CdS/CdTe solar cell on the resistivity and thickness of the p-CdTe absorber layer, the noncompensated acceptor concentrationN_a–N_d, and carrier lifetime τ inCdTe, are investigated, and optimization of these parameters in order to improve the solar cell efficiency is performed. It has been shown that the observed low efficiency of CdS/CdTe solar cells is caused by the too short electron lifetime in the range of 〖10〗^(-10)–〖10〗^(-9) s and too thin (3–5 μm) CdTe layer currently used for fabrication of CdTe/CdS solar cells. To achieve an efficiency of 28–30%, the resistivity and thickness of the CdTe absorber layer, the noncompensated acceptor concentration, and carrier lifetime should be∼0.1 Ω•cm,≥20–30 μm,≥〖10〗^16 〖cm〗^3, and ≥〖10〗^(-6) s, respectively.
Tile: DESIGN OF II-VI THIN FILM SOLAR CELLS A b s t r a c t CdTe thin films are used as absorber ... more Tile: DESIGN OF II-VI THIN FILM SOLAR CELLS A b s t r a c t CdTe thin films are used as absorber layer in CdS/CdTe solar cells. The microstructure of this layer plays a fundamental role in photovoltaic conversion potential where their conversion efficiency is in the range of 18–24% with low-cost manufacturability. In this work, we study the effect of the thickness of the CdTe absorber layer on the efficiency of a thin-film CdS/CdTe heterostructure to find their best combination for improvement of the solar cell efficiency. To explore the possibility of ultra thin and high efficiency CdS/CdTe solar cell, the thickness CdTe absorber layer was increased and found that 4 μm thin CdTe layer showed reasonable efficiency.
The CGS and CIGS being promising materials for large scale photovoltaic applications, the effect ... more The CGS and CIGS being promising materials for large scale photovoltaic applications, the effect of temperature on the electrical parameters of a CGS/CIGS tandem solar cell has been investigated in this work. The copper gallium diselenide (CGS) and copper indium gallium diselenide (CIGS) structures as topcell and bottom-cell respectively, were numerically simulated under AM1.5G spectral illumination using the two-dimensional device simulator Silvaco-Atlas. The temperature dependency of the solar cell’s characteristics was investigated in the temperature range from 300 to 400 K at intervals of 20 K. The simulation results show the density current (Jsc) slightly increases whereas the open-circuit voltage (Voc) and fill factor (FF), conversion efficiency () decreases with the increase in temperature. The tandem cell operating temperature efficiency was found to be (– 0.34 %/K), which is slightly higher than that of CGS solar cell (– 0.29 %/K), but markedly better than that of CIGS solar cell (– 0.41 %/K).
The solar spectrum can be divided by tandem solar cells into several subcells that have different... more The solar spectrum can be divided by tandem solar cells into several subcells that have different bandgaps which convert, more effectively, the light into electricity than the single cells. In this study, the simulation of the photovoltaic (PV) characteristics of a CZTS/CZTSe tandem solar cell, based on structures of copper zinc tin sulfide (CZTS) as a top cell and copper zinc tin selenide (CZTSe) as a bottom cell, was accomplished by using SCAPS-1D simulator under AM1.5 illumination. Initially, the simulation of single CZTS and CZTSe solar cells was performed to give efficiency of 14.37 % and 17.87 %, respectively, which are in good agreement with the literature results. Before feeding with filtered spectrum, the simulated PV parameters of the CZTS/CZTSe tandem solar cell are the conversion efficiency (ƞ) of 20.68 % and the shortcircuit current density (Jsc) of 20.205 mA/cm2 of the top and bottom cells with arbitrary normal thicknesses. Furthermore, and in order to reach the matching current, both top and bottom cells have been investigated at different thicknesses for tandem configuration after validation, where the performance of the top and bottom cells is at thicknesses ranged from 0.05-0.5 µm and 0.1-1 µm, respectively. The performance of the tandem solar cell is determined after filtered spectrum feeding and current matching. The Jsc of CZTS/CZTSe tandem solar cell is 20.33 mA/cm2 for 0.255 µm thick of the top, CZTS, cell and 0.8 µm of the bottom, CZTSe, cell. The maximum ƞ of 22.98 % is reached for tandem structure design with open circuit voltage (Voc) enhancing of 1.48 V.
The CGS and CIGS being promising materials for large scale photovoltaic applications, the effect ... more The CGS and CIGS being promising materials for large scale photovoltaic applications, the effect of temperature on the electrical parameters of a CGS/CIGS tandem solar cell has been investigated in this work. The copper gallium diselenide (CGS) and copper indium gallium diselenide (CIGS) structures as topcell and bottom-cell respectively, were numerically simulated under AM1.5G spectral illumination using the two-dimensional device simulator Silvaco-Atlas. The temperature dependency of the solar cell’s characteristics was investigated in the temperature range from 300 to 400 K at intervals of 20 K. The simulation results show the density current (Jsc) slightly increases whereas the open-circuit voltage (Voc) and fill factor (FF), conversion efficiency () decreases with the increase in temperature. The tandem cell operating temperature efficiency was found to be (– 0.34 %/K), which is slightly higher than that of CGS solar cell (– 0.29 %/K), but markedly better than that of CIGS solar cell (– 0.41 %/K).
The solar spectrum can be divided by tandem solar cells into several subcells that have different... more The solar spectrum can be divided by tandem solar cells into several subcells that have different bandgaps which convert, more effectively, the light into electricity than the single cells. In this study, the simulation of the photovoltaic (PV) characteristics of a CZTS/CZTSe tandem solar cell, based on structures of copper zinc tin sulfide (CZTS) as a top cell and copper zinc tin selenide (CZTSe) as a bottom cell, was accomplished by using SCAPS-1D simulator under AM1.5 illumination. Initially, the simulation of single CZTS and CZTSe solar cells was performed to give efficiency of 14.37 % and 17.87 %, respectively, which are in good agreement with the literature results. Before feeding with filtered spectrum, the simulated PV parameters of the CZTS/CZTSe tandem solar cell are the conversion efficiency (ƞ) of 20.68 % and the shortcircuit current density (Jsc) of 20.205 mA/cm2 of the top and bottom cells with arbitrary normal thicknesses. Furthermore, and in order to reach the matching current, both top and bottom cells have been investigated at different thicknesses for tandem configuration after validation, where the performance of the top and bottom cells is at thicknesses ranged from 0.05-0.5 µm and 0.1-1 µm, respectively. The performance of the tandem solar cell is determined after filtered spectrum feeding and current matching. The Jsc of CZTS/CZTSe tandem solar cell is 20.33 mA/cm2 for 0.255 µm thick of the top, CZTS, cell and 0.8 µm of the bottom, CZTSe, cell. The maximum ƞ of 22.98 % is reached for tandem structure design with open circuit voltage (Voc) enhancing of 1.48 V.
Zinc oxide (ZnO) is one of the best transparent conducting oxide (TCO) materials with a wide band... more Zinc oxide (ZnO) is one of the best transparent conducting oxide (TCO) materials with a wide bandgap and good electrical and optical properties. Its low cost, nontoxicity and transparency in the optical region of the electromagnetic spectrum make it very promising candidate for solar cell applications. In this work, zinc acetate precursor was used to grow a ZnO thin film by using sol-gel spin-coating technique. The surface morphological study using scanning electron microscope (SEM) was carried out to confirm the growth pattern and crystal distribution. The optical properties, transmission (T), reflection (R), optical bandgap (Eg), refractive index (n), and extinction coefficient (k) were extracted and investigated to be used in the simulation of ZnO/Cu2O heterostructure solar cell, where ZnO thin film plays a double role: as the TCO window, as well as the emitter of the n-p junction. However, the solar cell showed weak external quantum efficiency (EQE) compared to those prepared by using zinc nitrate and diethyl zinc precursors. TCAD numerical simulation was used to clarify the origin of this weak EQE by taking into account two parameters. The first studied parameter is the root-mean-square interface roughness, RMS, in Haze modeling approach, H, which describes how much of incident light is scattered at the interface. The second studied parameter is the density of defects in the ZnO bulk with continuous distribution of states in its bandgap similar to an amorphous semiconductor made of tail bands and Gaussian distribution deep level bands. Consequently, and by adjusting and investigating the effect of the RMS and the constituents of the bandgap states, we were able to obtain a good agreement between simulated and measured EQE characteristics of the solar cell.
L‟énergie solaire est l‟une des filières très prometteuse comme alternatif aux sources d‟énergie ... more L‟énergie solaire est l‟une des filières très prometteuse comme alternatif aux sources d‟énergie classique. Mais le rendement des panneaux solaires aujourd‟hui sont loin d‟être concluantes pour le choix de cette filière. Le composant de base de cette filière est la cellule solaire. Cette dernière peut être réalisée par différents matériaux semi-conducteurs comme le silicium. Le Silicium monocristallin s‟avère très couteux. Une alternative moins chère est les cellules solaires en couches minces. Les meilleurs compromis rendement-cout sont les filières silicium amorphe (a-Si) et les semiconducteurs II-VI (CdO, CdTe, CdS, ZnO, ZnTe, ZnS…). Les oxydes conducteurs transparent (TCO : Transparent Conducting Oxides) des films minces ont une grande importance dans des applications de dispositifs électroniques. Ils sont basés sur les semiconducteurs II-VI qui sont souvent des oxydes métalliques (ZnO, CdO, MgO...). Ils sont des semiconducteurs de type n avec un gap d‟énergie élevée et il est c...
Transactions on Electrical and Electronic Materials, 2022
Zinc oxide (ZnO) thin films were deposited on glass substrates by using sol–gel spin coating tech... more Zinc oxide (ZnO) thin films were deposited on glass substrates by using sol–gel spin coating technique. Zinc acetate dihydrate and 2-methoxyethanol were used as precursor with different molar concentrations, 0.2 M, 0.3 M and 0.6 M. The effect of precursor concentration on the structural and optical properties, transmission (T), reflection (R), optical bandgap (Eg), Urbach energy (EU), refractive index (n), extinction coefficient (k), single-oscillator energy (E0), dispersion energy (Ed), moments M−1 and M−3, dielectric constant (ε) and optical conductivity (σ), of the ZnO thin films was studied and investigated. Although, the transmittance, slightly, decreased and the reflectance increased, as the molar concentration increased, the measurements showed that all samples have high transparency and low reflectivity in the visible range which make them suitable for solar cells applications. It is also found that, as the molarity increased, the ZnO thin films exhibited lower Eg and EU and higher Ed, M−1 and M−3.
• Fabrication of ZnO film by sol–gel using zinc acetate decomposition • Extraction of the optical... more • Fabrication of ZnO film by sol–gel using zinc acetate decomposition • Extraction of the optical parameters to be used in modeling a ZnO/p-Si solar. • This is to elucidate the solar cell weak performance • Defects in the ZnO bulk and the surface recombination velocity in the ZnO/p-Si interface were responsible. • The simulation led to comparable values between simulation and measurement of J-V characteristics.
This study is a numerical simulation obtained by using Silvaco Atlas software to investigate the ... more This study is a numerical simulation obtained by using Silvaco Atlas software to investigate the effect of different types of dielectric layers, inserted between the channel and the gate, on the performance and reliability of an a-ITZO TFT.
Cadmium oxide (CdO) is a semiconductor with promising electrical and optical properties. Pure CdO... more Cadmium oxide (CdO) is a semiconductor with promising electrical and optical properties. Pure CdO is an n-type degenerate semiconductor and is almost entirely transparent in the optical region of the electromagnetic spectrum. Thus, the interest in its study as a possible device for photo detectors and solar cells has increased significantly. However real solar cells, based on an n-CdO/p-Si heterostructures, show poor photovoltaic performance [1]. In this work numerical simulation is used to elucidate this poor performance. Figure 1 shows measured photovoltaic performance of an n-CdO/p-Si heterostructures [1]. We have simulated the same structure by considering two cases. The first is that CdO is a perfect material. The second models CdO as a semiconductor with continuous distribution of states in its band gap similar to an amorphous semiconductor. The density of states model used here is composed of four bands: two tail bands (a donor-like g_TD (E) and an acceptor-like g_TA (E)) and...
Tile: DESIGN OF II-VI THIN FILM SOLAR CELLS A b s t r a c t CdTe thin films are used as absorber ... more Tile: DESIGN OF II-VI THIN FILM SOLAR CELLS A b s t r a c t CdTe thin films are used as absorber layer in CdS/CdTe solar cells. The microstructure of this layer plays a fundamental role in photovoltaic conversion potential where their conversion efficiency is in the range of 18–24% with low-cost manufacturability. In this work, we study the effect of the thickness of the CdTe absorber layer on the efficiency of a thin-film CdS/CdTe heterostructure to find their best combination for improvement of the solar cell efficiency. To explore the possibility of ultra thin and high efficiency CdS/CdTe solar cell, the thickness CdTe absorber layer was increased and found that 4 μm thin CdTe layer showed reasonable efficiency.
Over the last two decades, the electromagnetic radiation is becoming the fourth public pollution ... more Over the last two decades, the electromagnetic radiation is becoming the fourth public pollution in addition to the noise, water and air pollution. Here, we had studied the structure and the electromagnetic properties of machine-knitted fabric coated with silver by means of microscopy and shielding effectiveness in the open space. The silver-plated polyester fabric showed a different shielding effectiveness of electromagnetic wave in the open space compared with enclosed space. The value of SE had closed relation with transmitting and receiving distance except the theory factor. When the frequency dropped below 900 MHz, the value SE usually became negative.
Dependences of the open-circuit voltage, short-circuit current, fill factor, and efficiency of a ... more Dependences of the open-circuit voltage, short-circuit current, fill factor, and efficiency of a CdS/CdTe solar cell on the resistivity and thickness of the p-CdTe absorber layer, the noncompensated acceptor concentrationN_a–N_d, and carrier lifetime τ inCdTe, are investigated, and optimization of these parameters in order to improve the solar cell efficiency is performed. It has been shown that the observed low efficiency of CdS/CdTe solar cells is caused by the too short electron lifetime in the range of 〖10〗^(-10)–〖10〗^(-9) s and too thin (3–5 μm) CdTe layer currently used for fabrication of CdTe/CdS solar cells. To achieve an efficiency of 28–30%, the resistivity and thickness of the CdTe absorber layer, the noncompensated acceptor concentration, and carrier lifetime should be∼0.1 Ω•cm,≥20–30 μm,≥〖10〗^16 〖cm〗^3, and ≥〖10〗^(-6) s, respectively.
Tile: DESIGN OF II-VI THIN FILM SOLAR CELLS A b s t r a c t CdTe thin films are used as absorber ... more Tile: DESIGN OF II-VI THIN FILM SOLAR CELLS A b s t r a c t CdTe thin films are used as absorber layer in CdS/CdTe solar cells. The microstructure of this layer plays a fundamental role in photovoltaic conversion potential where their conversion efficiency is in the range of 18–24% with low-cost manufacturability. In this work, we study the effect of the thickness of the CdTe absorber layer on the efficiency of a thin-film CdS/CdTe heterostructure to find their best combination for improvement of the solar cell efficiency. To explore the possibility of ultra thin and high efficiency CdS/CdTe solar cell, the thickness CdTe absorber layer was increased and found that 4 μm thin CdTe layer showed reasonable efficiency.
Zinc oxide (ZnO) is a semiconductor with promising electrical and optical properties. Pure ZnO is... more Zinc oxide (ZnO) is a semiconductor with promising electrical and optical properties. Pure ZnO is an n-type degenerate semiconductor and is almost entirely transparent in the optical region of the electromagnetic spectrum. Sol–gel spin-coating method was used to grow ZnO thin film from Zinc acetate decomposition. The optical properties were investigated to use them in simulation of a ZnO/Si heterostructure solar cell. However, the real solar cell shows poor photovoltaic performance. Numerical simulation is used to elucidate this poor performance. The same structure has been simulated, by using the experimental results, by considering the ZnO as a semiconductor with continuous distribution of states in its band gap similar to an amorphous semiconductor. The density of states model used here is composed of four bands: two tail bands and two Gaussian distribution deep level bands. Evidently the first case gave results far from reality. In the second case and by adjusting the constituents of the band gap states, it was possible to reproduce a good agreement between simulated and measured J-V characteristics of the solar cell.
— Graphene is a one atom thick two-dimensional material that exhibits exceptional physical and el... more — Graphene is a one atom thick two-dimensional material that exhibits exceptional physical and electronic properties, and is offering new avenues of applications in nanoelectronics, sensors and energy storage platforms. In this study, we report a sol-gel method to prepare graphene/polymer. The nanocomposite was prepared by using graphene. Structural properties of materials have been characterized by AFM, XRD and SEM. Fourier transform infrared (FTIR) were used to characterize the graphene oxide. Electrical resistivity of the the nanocomposites were analyzed by four probe technique. As a result, the application potential of graphene/polymer materials for photovoltaic solar cells and optoelectronic applications were investigated.
Zinc oxide (ZnO) is a semiconductor with promising electrical and optical properties. Pure ZnO is... more Zinc oxide (ZnO) is a semiconductor with promising electrical and optical properties. Pure ZnO is an n-type degenerate semiconductor and is almost entirely transparent in the optical region of the electromagnetic spectrum. Thus, the interest in ZnO study as a suitable material for photo detectors and solar cells has increased significantly. Sol–gel spin-coating method was used to grow ZnO thin films from Zinc acetate decomposition. The transmittance (T), reflectance (R), absorption coefficient (alpha (α)), optical band gap (Eg), refractive index (n), extinction coefficient (k), real dielectric constant ( 1), and imaginary dielectric constant ( 2) were investigated to use them in the simulation. However, real ZnO/Cu 2 O heterostructure solar cell based on ZnO (Zinc acetate decomposition) shows poor photovoltaic performance compared to zinc nitrate and diethyl zinc decompositions. Numerical simulation is used to elucidate this poor performance. The same structure has been simulated by considering two cases. The first is that ZnO is a perfect material. The second models ZnO as a semiconductor with continuous distribution of states in its band gap similar to an amorphous semiconductor. The density of states model used here is composed of four bands: two tail bands (a donor-like g TD (E) and an acceptor-like g TA (E)) and two Gaussian distribution deep level bands (an acceptor-like g GA (E) and a donor-like g GT (E)). Evidently the first case gave results far from reality. In the second case, however, and by adjusting the constituents of the band gap states we were able to reproduce a good agreement between simulated and measured J-V characteristics of the solar cell.
Indium Gallium Zinc Oxide (IGZO) thin films have attracted significant attention for application ... more Indium Gallium Zinc Oxide (IGZO) thin films have attracted significant attention for application in thin-film transistors (TFTs) due to their specific characteristics, such as high mobility and transparency. The performance a-IGZO thin film transistors (TFTs) with four different insulators (SiO2 Si3N4, Al2O3 and HfO2) are examined by using numerical simulation. It is found that the output performance is significantly enhanced with high relative permittivity of the insulator. The HfO2 gate insulator gives the best performance: lower threshold voltage and subthreshold, and higher field effect mobility, on current and Ion/Ioff ratio.
— In this study, nanostructured graphene was manufactured as powders by chemical technique. High ... more — In this study, nanostructured graphene was manufactured as powders by chemical technique. High performance polymer based composite materials with grapheme were obtained by sol-gel method. Electromagnetic shielding behaviour of manufactured composites were carried out in the frequency range from 9 GHz to 10 GHz by using Network Analyzer. Electrical proporties of nanocomposites were examined with electrical measurement system device. Surface morphologies and structural structural properties and of obtained composites were investigated by SEM and XRD analysis.
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Papers by Slimane Chala