Search

Abstract The tunability of the InGaN band gap energy over a wide range provides a noble spectral match to sunlight, making it a suitable material for photovoltaic solar cells. The ineffectiveness of single junction solar cell to convert solar full spectrum into electrical energy leads to transparency loss in addition with excess excitation loss. An efficient BSF layer is an essential structural element to attain high efficiency in solar cells. In this work the impact of the BSF layer for InGaN single-junction and multi-junction solar cells is studied using the computational numerical modeling with Silvaco ATLAS simulation technique. The open circuit voltage (Voc) and circuit current density (Jsc) characteristics of the simulated cells and the variation of external quantum efficiency as a function of solar cell structures have been studied. For the optimized cell structure, the maximum Jsc = 14.6 mA/cm2, Voc = 3.087 V, and fill factor (FF) = 88.15% are obtained under AM1.5G illumination, exhibiting a maximum conversion efficiency of 36.1%.

Here, an analytical model is proposed to solve in two dimensions the transport equations of the minority carriers, using the method of separation of variables. The present approach considers that the solar cell is composed, in addition to emitter and base regions, of a non-uniformly doped thin region at the back cell to improve the device output parameters. The model is used to investigate the influence of built-in electric field, grain size and recombination velocities (Sgb and Sb for the grain boundary and back surface respectively) on the distribution of excess carriers and the consequent photovoltaic characteristics. The results showed that, as compared to a typical n+p structure, the addition of a p+ rear surface field region enhances the solar cell's output characteristics under the AM1.5 spectrum. An optimum increase in conversion efficiency, open circuit voltage and photocurrent density were found to be 7.2% (from 14% to 15.02%), 6.4% and 5%, respectively. This demonstrates the potential of BSF cell designs to meaningfully improve commercial polycrystalline silicon solar cell's performance. Additional results indicate that higher performance parameters result from increasing grain size and decreasing grain boundary recombination velocity, and that only a modest electric field is sufficient to eliminate the impact of surface recombination velocity for values less or equal to approximately 5.10³ cm.s-1. Besides, to validate our approach, the values obtained for photovoltaic quantities were compared with other results reported in literature. A good agreement is found. [ABSTRACT FROM AUTHOR]

Performance of silicon solar cells using pure and Cd-doped SnSe as back surface field (BSF) layers in p-type Si wafer and n+-Si emitter has been simulated. Replacing n+-Si emitter with metal oxides, namely Cadmium oxide (CdO) and Tin oxide (SnO2), the improvement could be achieved in the solar cell parameters open circuit voltage (VOC), short circuit current density (JSC), fill factor (FF) and efficiency (η). Moreover, deposition of these oxides can be done at much lower temperatures compared to diffused Si emitters diffused at high temperatures. Also, the doped Si emitters make use of poisonous gases like diborane and phosphine. In this work, a low thermal budget silicon solar cell with pure and Cd-doped SnSe BSF and metal oxide emitters has been prepared. [ABSTRACT FROM AUTHOR]

Antimony (Sb) chalcogenides, particularly antimony selenide (Sb2Se3), have gained attention as promising semiconductor materials in order to creat and advancement of competitive solar cells. These materials exhibit a range of desirable qualities, such as excellent absorption rate, ability to modify band gap, and plentiful in the crust of the earth. This article describes an antimony selenide (Sb2Se3) absorber based high-efficient thin film solar cell (TFSC) with copper oxide (Cu2O) as as back surface field (BSF) by dint of Al/ITO/TiO2/Sb2Se3/Cu2O/Ni heterostructure using SCAPS-1D Simulator. This research entails an in-depth assessment of various physical and electrical characteristics of every solar active semiconductorof TiO2,Sb2Se3, and Cu2O covering the thickness of each layer, concentration of carrier doping, defect density in the bulk and at the interface, carrier generation rate together with recombination. Initially, the variation in photovoltaic parameters of open circuit voltage (Voc), short-circuit current density (Jsc), fill factor (FF), power conversion efficiency (PCE), and quantum efficiency (QE) investigated without the BSF layer, followed by a comprehensive analysis on the role of Cu2O BSF layer for enhancing cell's performance explored systematically. The proposed heterostructure shows improved PCE of over 32% (which was 21% without BSF) with JSC of 37.492 mA/cm2, VOC of 1.024 V, and FF of 83.595%. Thus, the utilisation of a heterostructure comprising Sb2Se3 absorber and copper oxide Cu2O BSF layer demonstrates significant promise in the development and production the high-efficiency greenery thin-film solar cells (TFSCs). [ABSTRACT FROM AUTHOR]

• We analyze the degradation behavior and current limiting unit of GaInP/GaAs/InGaAs triple-junction inverted metamorphic (IMM3J) solar cells under 1Mev electron irradiation. • We have improved the irradiation resistance of the IMM3J cell by optimizing the back surface field of the top-cell and bandgap of sub-cell on the basic IMM 3J solar structure. • We characterized the anti-radiation capability of different structure cells by calculating the minority carrier decay coefficient on reasonable assumption and derivation. Highly efficient, flexible, and lightweight thin-film solar cells play an important role in the aerospace field. To improve the radiation resistance of GaInP/GaAs/InGaAs triple-junction inverted metamorphic (IMM3J) solar cells under intense electron irradiation in space, the back field of the top cell and band gap of the middle cell were optimized. Under 1 × 1015 e/cm2 electron irradiation, compared with the reference cell, the attenuation of the conversion efficiency of the backfield-optimized cell and bandgap-adjusted cell was reduced by 10.3 % and 2.8 %, respectively. According to the spectral response and electrical properties, the current-limiting units of the different cells before and after irradiation were analyzed. The increase in the aluminum (Al) component increased the barrier of the AGaInP back surface field, promoted the carrier absorption of the top cell, and increased the initial current of the solar cell. Optimization of the bandgap in the middle cell enables the bottom cell with a redundant current to resist irradiation attenuation. Both adjustments optimize the current-matching relationship between the sub-cells after irradiation. The decay coefficient of the minority carrier was calculated using the electrical displacement damage theory, and the lifetime decay coefficient of the minority carrier was further estimated, which indicated that the radiation resistance was improved. In addition, the mechanism of improving the radiation resistance is discussed in detail by the characteristics of carrier transport, which provides an optimal direction for improving the irradiation characteristics of solar cells in the future. [ABSTRACT FROM AUTHOR]

In this paper, we present a simulation study of Cu(In,Ga)Se2 (CIGS) based solar cell using a physically based two-dimensional device simulator Silvaco-Atlas under AM1.5 illumination. First, we studied the effect of CIGS layer thickness, doping concentrations, and defects on the J–V properties and the quantum efficiency (QE) of a conventional cell. The simulated structure shows an open circuit voltage equal to 0.80 V, a short circuit current density equal to 30.03 mA/cm2, a fill factor equal to 82.77% and the obtained efficiency of the conventional cell is 19.80% with CIGS absorber layer thickness of about 1.5 μm, our simulation results of the CIGS solar cell are in good agreement with the simulated and experimental results found in literature. In order to improve the solar cells efficiency, the back surface field (BSF) based on hydrogenated microcrystalline silicon μc-Si:H(p+) layer has been inserted between the back contact (Mo) and the CIGS absorber layer, in this case the structure presents an open voltage equal to 0.84 V, a short circuit current density equal to 32.55 mA/cm2, a fill factor equal to 85.31% and an efficiency of 23.42%. The obtained results demonstrate that the addition of μc-Si:H(p+) BSF layer increases the efficiency of CIGS solar cells, reaching a maximum value of 23.42% for 1.5 μm of CIGS thickness and 10 nm for μc-Si:H(p+) BSF layer. [ABSTRACT FROM AUTHOR]

In the present work, a silicon-based single heterojunction solar cell is analyzed for its potentially low cost and high efficiency. To obtain an optimal device structure of CeO2/p-Si, SCAPS 1D was used to perform numerical modeling. We investigated the performance of the solar cell by evaluating the effect of varying important parameters. The thickness of the absorber (p-Si) and buffer (CeO2) layer was varied to observe its influence on the short-circuit current density (Jsc), open circuit voltage (Voc), fill factor (FF), and conversion efficiency (η) of the solar cell. Accordingly, the defects observed in the Si and CeO2 layers along with the role of CeO2/Si interface defect density were analyzed in detail to deliver guidelines for obtaining optimal efficiency. The CeO2 layer thickness was varied from 50 to 400 nm. The results indicate that the optimal structure for the CeO2/Si solar cell can be attained when the donor density in CeO2 is 1021 and the thickness of the CeO2 and p-Si layers is 50 nm and 2000 nm, respectively. The anticipated structure consists of CeO2 (n+)/Si (p)/Si (p+) layers and offers maximum efficiency of ~ 26% under an illumination spectrum of 1.5 G. Solar cell performance parameters including Jsc, Voc, QE (quantum efficiency/spectral response), FF, and η were analyzed graphically. The optimized structure may have a significant impact on the future development of advanced photovoltaic devices. [ABSTRACT FROM AUTHOR]

This paper aims in a simulation work of a novel hybrid heterostructure based on carbon nanotubes as absorber layer with its unique electronic properties in semiconductor technology, and copper barium tin sulfide (CBTS) compound as a back surface field. Cell optimization was investigated in SCAPS–1D software for the architectures ITO/CdS/SWCNTs and ITO/CdS/SWCNTs/CBTS. The device performance and the influence of different materials parameters such as thickness, carrier concentration, and defect density are analyzed in this article. After adding the BSF layer and optimized physical parameters, promising results were achieved with PCE of 30.92%, Voc of 0.83 V, Jsc of 43.47 mA/cm2, and FF of 86.18%. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ag-doped Cu 2 ZnSnS 4 (CAZTS) solar cell has been explored, with varying Ag concentrations (x = 0, 0.1, 0.2, 0.3, 0.4) in the composition (Cu 1−x Ag x) 2 ZnSnS 4. • To address back surface recombination, a Sn 2 S 3 layer was introduced as a back surface field layer in CAZTS solar cells. • The efficiency enhancement employs a bandgap grading approach, elevating efficiency from 15.8% to 24.7% compared to without a graded device. • The optimization of thickness, total defect density and doping of the CAZTS layer has been investigated. • Results showed a maximum efficiency of 27.3 % at a doping value of 1 × 1016 cm−3. The Ag-doped Cu 2 ZnSnS 4 (CAZTS) based solar cell has been explored, with varying Ag concentrations (x = 0, 0.1, 0.2, 0.3, 0.4) in the composition (Cu 1−x Ag x) 2 ZnSnS 4. In order to mitigate back surface recombination in CAZTS-based solar cells, a Sn 2 S 3 layer has been incorporated as a back surface field (BSF). Further, the efficiency enhancement employs a bandgap grading approach, elevating efficiency from 15.8 % to 24.7 % compared to devices without the graded structure. Additionally, the thickness and total defect density of the CAZTS layer are optimized. The result demonstrates that the optimized value of the CAZTS layer's thickness is 1.1 µm, and the defects are 1 × 1012 cm−3. To further enhance the performance, the doping variation of the CAZTS layer has also been investigated. The findings indicate that the maximum efficiency of 27.32 % is attained with a doping value of 1 × 1016 cm−3. [ABSTRACT FROM AUTHOR]

• Established the dependence of CZTS solar cell performance on defect density in bulk and at the interfaces. • Elucidated effect of field effect passivation at back contact in CZTS thin film solar cells. • Predicted an efficiency as high as 15.7% using a SnS back surface field layer. Although kesterite Cu 2 ZnSnS 4 (CZTS) has emerged as a potential absorber material for development of low cost thin film solar cells, the performance of the CZTS devices has been limited by a large deficit in open circuit voltage caused by recombinations of charge carriers primarily at the back contact interface. Recently, field passivation through engineering of the back contact interface has been shown to control the interface recombination and thereby minimise the open circuit voltage deficit. In this work, we have numerically established the limiting role of defect densities in the bulk of CZTS and at interfaces (CZTS-CdS and CZTS-Mo) on performance metrics of the champion CZTS cell (∼11%). Furthermore, we have shown that field passivation by using back surface field (BSF) layers in the form of very thin p+ type Cu 2 O and SnS layers, sandwiched between the bottom electrode Mo and CZTS, greatly improved the device efficiency (to about 15%) despite significant high bulk and interface defect densities. Numerical calculations have revealed critical dependence of back contact interface recombination on charge carrier concentration gradient and band offset at the interface, and thickness of the BSF layer. Based on the results, a mechanism for suppressing the recombinations at back contact interface has been illustrated. [ABSTRACT FROM AUTHOR]

The short hole diffusion length (HDL) and high interfacial recombination are among the main drawbacks of semiconductor-based solar energy systems. Surface passivation and introducing an interfacial layer are recognized for enhancing HDL and charge carrier separation. Herein, we introduced a facile recipe to design a pinholes-free BiVO 4 photoanode with a NiV 2 O 6 back contact interfacial (BCI) layer, marking a significant advancement in the HDL and photoelectrochemical activity. The fabricated BiVO 4 photoanode with NiV 2 O 6 BCI layer exhibits a 2-fold increase in the HDL compared to pristine BiVO 4 . Despite this improvement, we found that the front surface recombination still hinders the water oxidation process, as revealed by photoelectrochemical (PEC) studies employing Na 2 SO 3 electron donors and by intensity-modulated photocurrent spectroscopy measurements. To address this limitation, the surface of the NiV 2 O 6 /BiVO 4 photoanode was passivated with a cobalt phosphate electrocatalyst, resulting in a dramatic enhancement in the PEC performance. The optimized photoanode achieved a stable photocurrent density of 4.8 mA cm -2 at 1.23 V RHE , which is 12-fold higher than that of the pristine BiVO 4 photoanode. Density Functional Theory (DFT) simulations revealed an abrupt electrostatic potential transition at the NiV 2 O 6 /BiVO 4 interface with BiVO 4 being more negative than NiV 2 O 6 . A strong built-in electric field is thus generated at the interface and drifts photogenerated electrons toward the NiV 2 O 6 BCI layer and photogenerated holes toward the BiVO 4 top layer. As a result, the back-surface recombination is minimized, and ultimately, the HDL is extended in agreement with the experimental findings.

• Role of BSF layers thickness on different parameters of solar cell have been studied. • Optimization of SiGe layer thickness for the best performance. • Reduction in the front surface reflection and increase in absorption due to window layer. • Significant contribution in current density and internal quantum efficiency is notable for longer wavelength. • The maximum efficiency of nearly 17% has been achieved. This manuscript reports on an analytical study required to determine and enhance the effect of the high–low junction based back surface field (BSF) of thin n-CdS/p-SiGe/p + -BaSi 2 heterojunction solar cell. A 0.3 µm thick BSF layer made of extensively available and low-cost barium silicide (BaSi 2) is introduced into the basic SiGe solar cell for the first time. SCAPS-1D simulator is employed to analyze different parameters such as open circuit voltage (V oc), short-circuit current density (J sc), fill factor (FF), quantum efficiency (QE) and conversion efficiency (η) of the device. The SiGe absorber layer thickness is varied from 2 to 50 µm to analyze the device performance, however optimum results are observed between 10 and 15 µm. The BSF BaSi 2 layer thickness changing from 0.1 to 0.8 µm to check the viability of device for optimal efficiency. The present structure anticipates an efficiency of 17.05% for BSF layer thickness of 0.8 µm. In addition, the use of SiGe earth abundant material instead of CIGS having rare earth metals indium and gallium, reduces the overall fabrication cost of the solar cell. [ABSTRACT FROM AUTHOR]

In perovskite solar cells (PSCs), a defective perovskite (PVK) surface and cliff‐like energy offset at the interface always slow down the charge extraction; meanwhile, interface ion diffusion causes oxidation of the metal electrode, inducing device instability. Here, the in situ grown 2D‐(CH3NH2)3Sb2I9 (MA3Sb2I9) on the back surface of MAPbI3 results in a more robust interface. MA3Sb2I9 changes the MAPbI3 surface to p‐type and thus acts like a back surface field to drive charge extraction and suppress recombination, resulting in an obviously higher fill factor (FF) = 0.8 and power conversion efficiency (PCE) = 20.4% of SnO2/MAPbI3/MA3Sb2I9/Spiro‐OMeTAD (2,2′,7,7′‐Tetrakis[N,N‐di(4‐methoxyphenyl)amino]‐9,9′‐spirobifluorene) PSC than the pure MAPbI3 device. More importantly, strong chemical bonding of SbI prohibits ion diffusion, largely enhancing the thermal stability and longtime stability. Here, special 2D‐MA3Sb2I9 constructs' robust band alignment and chemical environment at the interface are highlighted for efficient and stable PSCs. [ABSTRACT FROM AUTHOR]

Solar cells are semiconductor devices that turn light into electricity. The performance analysis of a Gallium Arsenide (GaAs) based solar cell model was shown using the Analysis Microelectronic and Photonic Structures (AMPS-1D) simulator in this work. A balance of semiconductor compositions, layer thicknesses, and other factors had been studied. The effect of temperature on efficiency has been explored, as the thickness of the top gallium indium layer (GaInP). As the amount of phosphorus in double junction solar cells decreases, the efficiency increases. An efficient and optimised BSF layer is a key layer in both single junction and multi junction solar cells. The use of dual layer BSF for top cells with different thicknesses is explored in this GaInP/GaAs dual junction solar cell study using the Silvaco ATLAS computer numerical simulation TCAD tool. A low-high junction at the back end of a gallium arsenide solar cell has been studied. A back surface field (BSF) is generated by the n+ layer at the rear end of a standard p+ n junction solar cell, which improves the open-circuit voltage, short circuit current, fill factor, efficiency, and spectrum response. [ABSTRACT FROM AUTHOR]

This work reports on a numerical modeling of Cu2ZnSnSe4 (CZTSe) thin film based solar cells using Solar Cell Capacitance Simulator (SCAPS). First, a conventional CZTSe/CdS/ZnO solar cell structure has been proposed and optimized. The optimal output parameters (power conversion efficiency PCE = 24.50%, short circuit current density Jsc = 47.732 mA/cm2, fill factor FF = 80.478% and open circuit voltage Voc = 0.639 V) have been obtained for ZnO, CdS and CZTSe layer thicknesses closed to 0.02 μm, 0.02 μm and 1.5 μm, respectively. Next, to improve on the conventional solar cell performance, three cell structures with different highly P-doped materials as back surface field (BSF) layers, such as P+-CZTSe, P+-Cu2O and P+-CZTS, have been proposed and optimized. In comparison to the conventional cell, devices with BSF layer have shown improvements of all the photovoltaic parameters. The CZTS/CZTSe/CdS/ZnO device has provided the highest performance (PCE = 25.83%, Jsc = 51.04 mA/cm2, FF = 78.14% and Voc = 0.646 V) for ZnO, CdS, CZTSe and P+-CZTS thicknesses closed to 0.02 μm, 0.02 μm, 1.5 μm and 0.4 µm, respectively. Additionally, the generation rate is no affected by the BSF layer; however, the recombination rate has decreased in the bulk and back surface of the CZTSe absorber. Finally, the insertion of the BSF layer has caused an increase of external quantum efficiency (EQE) up to 94.5% and a slight red shift of absorption in the long-wavelength region near the band edge. [ABSTRACT FROM AUTHOR]

The back-surface field (BSF) layer obtained through the laser fired contact (LFC) process is the key to increasing the efficiency of solar cells. In this paper, we studied the optimization of LFC process parameters—focusing on laser frequency, influence, and speed—to achieve good ohmic contacts, and to reduce the heat-affected zone (HAZ). As frequency increases, interactions between the laser and particles increase, with the particles becoming overly heated. This generates the thermal effect, in which heat is transferred to particles not directly affected by the laser—resulting in the HAZ becoming wider and deeper. Under different laser power conditions, depths of approximately 18 and 8.3 μm were observed at laser speeds of 10 and 100 mm/s, respectively. This analysis of performance variables allowed us to identify those best suited to forming an Al-BSF layer approximately 1.2 μm thick, which resulted in the best LFC procedure while minimizing the HAZ area. HAZ size was minimized at a frequency of 400 kHz, using 5 W laser power, and a laser speed of 100 mm/s, while the best cell characteristics were obtained using a laser pitch of 500 μm and a single laser process. [ABSTRACT FROM AUTHOR]

Optimization of back surface field (BSF) for crystalline silicon solar cells was carried out by Afors-Het simulation software. Thickness and doping concentration parameters were optimized and electrical parameters of solar cells both with BSF and non-BSF were analyzed. The optimum BSF thickness and doping concentration for the crystalline silicon solar cell were determined as 7 μm and 1x1019 cm-3, respectively. A special attention was given to the estimation of peak firing temperature considering the printing amount of aluminum paste in order to form an optimal BSF by the calculations using Al-Si binary phase diagram. It was concluded that the temperature of up to 950oC should be established if an amount of 3 mg/cm2 printed aluminum was used to achieve BSF thickness of 7 μm, where 775 oC would be enough when the amount of aluminum is 8 mg/cm2. [ABSTRACT FROM AUTHOR]

Industrial bifacial n‐type front and back contact (nFAB) silicon solar cells, consisting of a boron‐doped p+ emitter and a phosphorus‐doped n+ back surface field (BSF), are known to give good bifaciality, high and stabilized efficiency. One possible approach to further enhance the cell efficiency is to convert conventional passivated emitter and rear totally diffused (PERT) into rear locally diffused (PERL) structure. Herein, bifacial nFAB PERT and PERL cells are fabricated by combining atmospheric pressure chemical vapor deposition (APCVD) of phosphosilicate glass (PSG) as doping source and laser processing. For PERL cells, two approaches are studied to locally form phosphorus‐doped BSF: 1) laser doping, and 2) laser ablation of a diffusion barrier layer. For ablation approach, an alkaline treatment is introduced immediately after laser process, which leads to the formation of locally textured BSF. Due to this locally textured contact, the resultant fill factor (FF) and series resistance (Rs) loss of the PERL cells are even less than that of the reference PERT cells. As a result, the champion cell of PERL shows a good efficiency of 21.3% with open‐circuit voltage (Voc) of 662 mV, short‐circuit current density (Jsc) of 39.6 mA cm−2, and a high FF of 81.1%. [ABSTRACT FROM AUTHOR]

We performed an investigation on the behaviour of the electrical parameters of ultrathin Cu(In,Ga)Se 2 (CIGS) solar cells buffered with Zn(O,S). Using one-dimensional simulations and by defining a new structure, we achieved a significant reduction of the absorber and the buffer layers to evaluate the changes in the cell’s performance. The simulation results revealed that a good optimisation of the thickness and sulphur content of the Zn(O,S) buffer layer could be an ingenious way to reduce the thickness of the absorber without compromising the performance of the solar cells. A high efficiency of 16.9% is obtained for 0.5 μ m of the absorber layer when the thickness and sulphur content of the Zn(O,S) layer are 10 nm and 0.9 respectively. At this configuration, we introduced p + -CIGS and SnS layers at the CIGS/Mo interface as back surface field (BSF) to reduce interface recombinations, which are very predominant in ultrathin absorber. An improvement of 2% and 5.96% on the efficiency is obtained with the p + -CIGS and SnS layers respectively. The shape of the band diagram shows good alignment and low band bending at the CIGS/OVC/Zn(O,S) interfaces and the corresponding conduction band offset is + 0.2 eV between the CIGS and the Zn(O,S) layers. Ultrathin CIGS and Zn(O,S) layers can be helpful in improving the stability of the cell with regard to the results obtained from the electrical parameters. [ABSTRACT FROM AUTHOR]

• The rear side metallization procedure suitable for the shingled PV module is developed. • The firing temperature profile is adjusted to eliminate the contact peeling. • The rear Ag pad on Al contact appear higher efficiency compared to Ag pad without Al. • The interconnected cells show the higher efficiencies than those of cleaved cells. The shingled photovoltaic (PV) module is a high-power PV module technology that is manufactured cells dividing and bonding with an electrically conductive adhesive (ECA). Here, the ECA is composed of 70–80% of silver, an acrylic, and a solvent. We focused on the formation of solar cell metallization suitable for the shingled PV module. Generally, the Ag pads on the rear side of the crystalline Si solar cells don't printed on the Al surface because of the peeling problem. Therefore, a back surface field (BSF) layer is not formed at this area. The characteristics of the solar cell can be improved by applying a rear Ag pad together with the BSF layer in the entire area of the back surface of the solar cell. The formation of the Al-BSF layer and the peeling of the Ag pad off from the interface between Al-BSF and Al were analyzed using by a scanning electron microscope. The peeling phenomenon could be removed by the adjustment of the elevation rate to the peak temperature during co-firing process. The external quantum efficiency (EQE) analysis revealed the influence of the full Al-BSF layer on the rear side of the solar cells showing higher values in the long-wavelength region. Additionally, the divided cell strips were interconnected via ECA bonding, and the characteristics were investigated. The interconnected cell exhibited the efficiency of 18.302% while the efficiencies of two cell strips were 18.039% and 18.162%, respectively. [ABSTRACT FROM AUTHOR]

The back-surface field (BSF) layer obtained through the laser fired contact (LFC) process is the key to increasing the efficiency of solar cells. In this paper, we studied the optimization of LFC process parameters—focusing on laser frequency, influence, and speed—to achieve good ohmic contacts, and to reduce the heat-affected zone (HAZ). As frequency increases, interactions between the laser and particles increase, with the particles becoming overly heated. This generates the thermal effect, in which heat is transferred to particles not directly affected by the laser—resulting in the HAZ becoming wider and deeper. Under different laser power conditions, depths of approximately 18 and 8.3 μm were observed at laser speeds of 10 and 100 mm/s, respectively. This analysis of performance variables allowed us to identify those best suited to forming an Al-BSF layer approximately 1.2 μm thick, which resulted in the best LFC procedure while minimizing the HAZ area. HAZ size was minimized at a frequency of 400 kHz, using 5 W laser power, and a laser speed of 100 mm/s, while the best cell characteristics were obtained using a laser pitch of 500 μm and a single laser process.

This research paper demonstrates the use of doping concentration effect of front surface field (FSF), back surface field (BSF), and emitter for high-efficiency of n-type monocrystalline silicon (c-Si) interdigitated back-contact (IBC) solar cells using Silvaco TCAD package. The integrated-back contact solar cell is considering as a promising structure due to its high conversion efficiency, thinner substrate, and low-temperature processing of the substrate configuration. From previous research works, the considered IBC cell of 150-μm thick n-type CZ silicon wafers with a half-pitch size of 500 μm is studied and improved for either product quality and lower operating costs. The optimum conversion efficiency of about 24.79% has been achieved with open-circuit voltage up to 726 mV under the AM1.5 spectrum. Furthermore, the solar incident angle plays a critical factor affecting the considered device characteristics and performance of the fixed PV modules. [ABSTRACT FROM AUTHOR]

Abstract In this research work, SCAPS-1D simulator is used to model and investigate the CZTS (Cu 2 ZnSnS 4) solar cells. A substrate cell structure ZnO/CdS/CZTS/Mo was used as a base model. A novel structure is proposed in which a back surface field (BSF) layer is inserted in order to improve the solar cell performances. A CZTS layer has been added as BSF layer. The obtained results present an increase in efficiency of CZTS solar cell from 12.03% to 14.03%. An optimization of different physical parameters (Thickness and doping concentration) of BSF layer has been done, the improvement on the electrical parameters of the solar cell was achieved (ƞ = 14.16%, Voc = 0.997 Volt, Jsc = 24.63mA/cm2 and FF = 57.65%) according to 1E18 cm−3 value of doping concentration and 0.1 μm thickness, the enhancing in the electrical efficiency is about 17.70%. The optimum value of BSF layer thickness is considered as 70 nm according to 1E18cm−3 of doping concentration with a conversion efficiency of 14.11% under 1.5 AMG illuminations, which corresponding to following electrical parameters: Jsc = 24.57 mA/cm2, Voc = 0.988 Volt, and fill factor = 58.06%. Also, at the end, the effect of the BSF layer on the band diagram and the generation-recombination profiles of CZTS solar cell is discussed. [ABSTRACT FROM AUTHOR]

Graphical abstract Schematic representation and band diagram of two cells configuration at the equilibrium: (a) with SDL layer (conventional structure), (b) with P + layer (new structure). Highlights • We made a compared study of CIGS solar cell structure, containing SDL layer, with a new reference cell containing P+ layer. • The optimal thickness of the P+ to optimize the solar cells is 10 nm. • The P+ defect density is the critical parameter for the limitation of the performance for the CIGS solar cells. • A wide band-gap BSF layer at the CIGS/Mo interface combined with a p+ layer provides a high-performance and stable CIGS solar cells. Abstract One dimension solar cells simulator package (SCAPS) is used to study the possibility of carrying out thin CIGS solar cells with high and stable efficiency. In the first step, we modified the conventional ZnO:B/i-ZnO/CdS/SDL/CIGS/Mo structure by substituting the SDL layer with the P + layer, having a wide bandgap from 1 to l.12 eV. Then, we simulated the J-V characteristics of this new structure and showed how the electrical parameters are affected. Conversion efficiency of 18.46% is founded by using 1.1 μm of P + layer thickness. Secondly, we analyze the effect of increase thickness and doping density of CIGS, CdS and P + layers on the electric parameters of this new structure. We show that only the short-circuit current density (J SC) and efficiency are improved, reaching respectively 34.68 mA/cm2 and 18.85%, with increasing of the acceptors density. Finally, we introduced 10 nm of various electron reflectors at the CIGS/Mo interface in the new structure to reduce the recombination of minority carriers at the back contact. High conversion efficiency of 23.34% and better stability are obtained when wide band-gap BSF is used. [ABSTRACT FROM AUTHOR]

Low temperature processing of crystalline Si solar cells is attractive due to lower wafer and manufacturing costs. For thinner silicon wafers, thermal mismatch between Al and Si at high temperatures leads to thermal stress and wafer bowing. In this paper, replacement of back surface Al BSF contact by ITO films has been investigated as a function of Al-doping level. ITO films were deposited on back Si surfaces with sheet resistances in ∼16–48Ω/□ range. ITO/Si contact resistance increases slightly as sheet resistance is reduced, however, the variation is not significant. At sheet resistance of 25Ω/□, solar cell performance comparable to conventional AL BSF configuration. Even at sheet resistance ∼50Ω/□, it is possible to form high quality ITO/Si contact. The role of surface defects has been deemed to be critical. Without etching of Al-doped surface, surface quality is poor due to defects originating from the Al-alloy formation. As these defects are removed with controlled etching, a more pristine surface emerges that forms superior contacts with ITO film.

Numerical analysis of the proposed solar cell is based on cadmium telluride (CdTe) and copper gallium sulfide (CuGaS2), also known as CGS, is proposed in this research work. Performance of a CdTe/CGS/CdS/ZnO cell is analyzed in Solar Cell Capacitance Simulator (SCAPS) software, by changing the physical parameters like doping density of acceptor, doping density of donor, absorber thickness and buffer thickness. The cell structure is in the same order as the CGS/CdS/ZnO with CdTe used for the back surface field layer. Power conversion efficiency of the CGS/CdS/ZnO solar cell without CdTe is 10.578% (with FF = 83.70%, Voc = 0.82 V, Jsc = 15.40 mA/cm2) and conversion efficiency of CdTe/CGS/CdS/ZnO is 28.20% (with FF = 77.66%, Voc = 1.22 V, Jsc = 29.63 mA/cm3). The overall investigation and simulation results from the modeling of a proposed device in SCAPS is very useful for the understanding of the fundamentals of photovoltaic devices and gives feedback to engineers and designers for the fabrication of CdTe/CGS based solar cells. [ABSTRACT FROM AUTHOR]

Cu 2 ZnSnS 4 ( CZTS ) is non-toxic earth abundant material and a promising quaternary semiconductor compound of group I-II-IV-VI having kesterite symmetrical structure. Due to its optimum direct band gap, it has been considered suitable material for absorber layer for photovoltaic solar cell applications. This paper presents numerical modeling of experimentally designed CZTS solar cell by applying CZTSe as back surface field (BSF) layer. In this work we reproduced results for experimentally designed CZTS solar cell in SCAPS software. The simulated results are validated and compared with real experimental results. After optimization of cell parameters conversion efficiency of an optimized device is increased up to 6.42% (with CZTS thickness of 0.8 μm). With further optimization and applying CZTSe BSF layer conversion efficiency increased up to 12.92%. Under 1.5 AM illumination condition from the proposed cell promising results had been achieved with short circuit current ( J sc ) 27.41 mA / cm 2 , open circuit voltage ( V oc ) 744.4 mV, fill factor ( FF ) 63.35% and corresponding to a total area conversion efficiency of 12.92%. [ABSTRACT FROM AUTHOR]

Currently, the conversion efficiency of Cu 2 ZnSn(S, Se) 4 (CZTSSe) thin film solar cell is mainly limited by its low open-circuit voltage. In this work, the performances of CZTSSe thin film solar cell were calculated by the simulation program AFORS-HET v2.5 to reveal some useful ways to enhance the open-circuit voltage. First, several factors affecting the open-circuit voltage were analyzed. The open-circuit voltage of CZTSSe solar cell was significantly improved by reducing the defect states, interface states, parasitic resistance effect, and formation of MoS 2 layer, and adjusting the hole concentration or band gap of CZTSSe absorber. Then, the band gap gradient was introduced into the CZTSSe absorber to extend the built-in electric field and enhance absorptions, leading to benign impacts on the open-circuit voltage of CZTSSe solar cell. Finally, a back surface field was considered for the CZTSSe solar cell. The effects of CZTSSe and amorphous silicon back surface fields depended on the defect states. The advantage of back surface field was prominent when the defect density was low. It was necessary to reduce the defects before considering a back surface field. In the calculations, the best CZTSSe solar cell had an open-circuit voltage deficit of only 0.134 V. The numerical analyses in this work provide some methods to improve the open-circuit voltage and conversion efficiency CZTSSe thin film solar cell. The proposed methods offer guidance for experimental works. [ABSTRACT FROM AUTHOR]

In this study, the CZTSSe (Cu 2 ZnSn(S,Se) 4 ) solar cells, with Al/ZnO:Al/ZnO (i)/CdS/CZTSSe/Mo structure, have been simulated. The simulation results have been compared and validated with real experimental results. Next, suggestions for improving the performance of CZTSSe solar cell have been provided. A SnS layer has been used as back surface field (BSF) layer. Different physical parameters of SnS layer are investigated, and the optimum values are selected. It has been found that by inserting a BSF layer with optimum parameters, the efficiency of CZTSSe solar cell increases from 12.3% to 17.25% due to enhancement of both short-circuit current density (Jsc) and open circuit voltage (Voc). For this optimized cell structure, the maximum Jsc =  37.37 mA / cm 2 , Voc =  0.605 V, and fill factor =  76.28% are obtained under 1.5 AM illumination. [ABSTRACT FROM AUTHOR]

Copyright of Electronic Components & Materials is the property of Electronic Components & Materials and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

High efficiency ultrathin CdTe film is an excellent candidate for reliable, efficient, stable and low cost solar cells. In this paper, a high efficiency CdS/CdTe solar cell has been studied by using ADEPT 1D simulation tool. The proposed device has been simulated with a reduced CdTe absorber layer thickness and a ZnTe layer as back surface field (BSF) which substantiates sensible energy conversion efficiency. The investigation into the simulation results showed that the conversion efficiency with BSF layer and 1 μm thick CdTe absorber is 8.24% more as compared to the conventional CdTe cells (without BSF layer). Reduction of minority carrier recombination loss due to the insertion of BSF layer at the back contact in ultra-thin CdS/CdTe cells has also been investigated. The results depict that CdTe cell with BSF layer is responsible for increasing the quantum efficiency. However, the proposed structure of ZnO/CdS/CdTe/ZnTe demonstrates the highest efficiency of 24.66% (Voc = 946.51 mV, Jsc = 34.40 mA/cm2 and FF = 75.72%) under global AM1.5G illumination spectra.