Numerical assessment of optoelectrical properties of ZnSe–CdSe solar cell-based with ZnO antireflection coating layer

Toward improving the performance of Cu2ZnSnS4-based solar cells with Zr, W or sulfurized layers at the SnO2:F/Cu2ZnSnS4 rear interface

Sputtered transparent electrodes for optoelectronic devices: Induced damage and mitigation strategies

Background and Objectives: In this article, the functionality of solar cells structure based on CuIn1-xGaxSe2 is investigated. This type of solar cell consists of different layers, namely, ZnO (TCO layer), Cd_S (Buffer layer), CIGS (Absorbent layer), and MO (Substrate layer). Two layers, Cd_S and CIGS, form a PN Junction. Methods: CIGS thin film solar cell is simulated using SILVACO software. The absorbent layer doping was originally changed. Later doping was kept constant and P-type layer of InAsP was added. Their effect on cell function was observed and examined. It was observed that after doping some parameters of the solar cell have improved whilst some others have decreased. It was also concluded that examined increase or decrease in the amount of dopant would reduce our efficiencies of solar cell. Results: Added the InAsP layer leads to increased open circuit voltage, short circuit current and the solar cell power, consequently gives the efficiency about 33.2%, which is an acceptable efficiency. Conclusion: It was clear that extreme increase or decrease in the amount of dopant in the absorbent layer can change solar cell parameters, and can improve cell functionality. The amount of dopants can also alter some other solar cell parameters which are not desirable, the added InAsP layer leads to increased open circuit voltage, and short circuit current and the solar cell power, consequently gives the about 33.2%, efficiency which is an acceptable efficiencies.======================================================================================================Copyrights©2018 The author(s). This is an open access article distributed under the terms of the Creative Commons Attribution (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, as long as the original authors and source are cited. No permission is required from the authors or the publishers.======================================================================================================

Minimizing the photon losses by depositing an anti-reflection layer can increase the conversion efficiency of the solar cells. In this paper, the impact of anti-reflection coating (ARC) for enhancing the efficiency of silicon solar cells is presented. Initially, the refractive indices and reflectance of various ARC materials were computed numerically using the OPAL2 calculator. After which, the reflectance of SiO2,TiO2,SiNx with different refractive indices (n) were used for analyzing the performance of a silicon solar cells coated with these materials using PC1D simulator. SiNx and TiO2 as single-layer anti-reflection coating (SLARC) yielded a short circuit current density (Jsc) of 38.4 mA/cm2 and 38.09mA/cm2 respectively. Highest efficiency of 20.7% was obtained for the SiNx ARC layer with n=2.15. With Double-layer anti-reflection coating (DLARC), the Jsc improved by ∼0.5 mA/cm2 for SiO2/SiNx layer and hence the efficiency by 0.3%. Blue loss reduces significantly for the DLARC compared with SLARC and hence increase in Jsc by 1 mA/cm2 is observed. The Jsc values obtained is in good agreement with the reflectance values of the ARC layers. The solar cell with DLARC obtained from the study showed that improved conversion efficiency of 21.1% is obtained. Finally, it is essential to understand that the key parameters identified in this simulation study concerning the DLARC fabrication will make experimental validation faster and cheaper.

Design structure of semiconductor window and absorber layers’ materials in thin film solar cells is an essential trend for specifying optical and electrical characteristics of thin film solar cells. This paper has been improved the optical and electrical characteristics and efficiency of traditional HJ-QDSc (ITO/CdS/QDPbS/Au) model by using the quantum dot window layer instead of bulk structure layers’ cell. Moreover, this paper represents new design for absorber layer using QD aluminium core/PbS shell absorber layer structure instead of QD PbS absorber layer to use the merits of QD metallic-semiconductor core/multiple shell structure to enhance the performance of previous CdS/QDPbS HJ-QDSc model. The proposal design structure is carried out by replacing the bulk CdTe, CIGS absorber layers and CdS window layer with quantum dot size window layer material and QD core/multiple shell absorber layer based on traditional (SnO2/CdS/CdTe/Cu) and (ZnO/CdS/CIGS/Mo). The proposal design structure on three-types of core/multiple shell for quantum dot based on heterojunction thin film solar cells has been applied. A comparison study has been established between the proposal design and traditional thin film solar cells based on sub-micro absorber layer thickness models.

An anti-reflection coating (ARC) with sub-micrometer size of structure has brought significant advantage in solar cell efficiency. Owing to the diffraction and light trapping effect caused by a sub-wavelength size of structure, the reduced reflectance covering a wide-wavelength can be expected at a surface of the photovoltaic (PV) cell. We proposed and tried a nano-scale structure fabrication by small-size particles combined with conventional 2 layers ARC on GaAs PV cells. The small-size spherical particles show well aligned self-assembly on the substrate when the solution containing micro-spheres were dried with a proper sheer force. Using the pure water solution of colloidal SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> spheres and an ordinal spin-coating technique, a well aligned mono-particle layer has been fabricated on the 2 layer ARC (TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> and SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) on a GaAs PV cell. In this research, we tried 3 samples with different size of particles (400 nm, 200 nm and 100 nm in diameter). As the evaluation of PV cell, I-V characteristics under the AM1.5G illumination and external quantum efficiency (EQE) spectra were measured. For each sample, the I-V and EQE were obtained from the same sample: before and after application of particle coating. Measured relative efficiency enhancement of the additional mono-layer coating was +7.1, +5.7 and -0.3 in % for particle sizes of 100, 200 and 400 nm, respectively. As well as enhancement in light incorporation to the inside of a PV cell, there seem to be scattering loss by the particles on the cell. In the range of tested particle size, the smaller particle was preferable to avoid scattering loss and provides a larger efficiency enhancement to GaAs PV cells.

This paper gives a synopsis of a CZTS-based n-CdS/p-CZTS/p + -AgGaTe2/p++-MoS2 thin film solar cell that has been designed and explored by the simulation technique with the help of a solar cell capacitance simulator (SCAPS-1D). The design utilizes CdS as the window layer, CZTS as the first absorber layer, AgGaTe2 as the second absorber layer, and MoS2 as the BSF layer. The influencing parameters of these materials such as thickness, doping concentration, and defect density have been adjusted to achieve the right balance between the proposed structure and to see the changes that affect the device's overall performance. In ideal condition, the single n-CdS/p-CZTS heterojunction structure shows power conversion efficiency (PCE) of 17.75% with short circuit current, JSC of 24.82 mA/cm2, open circuit voltage, VOC of 0.88 V and fill factor (FF) of 81.3%. But, with the inclusion of MoS2 as the BSF, the overall PCE is elevated to 25.84% with VOC of 1.09 V, JSC of 26.96 mA/cm2 and FF of 87.64%. Finally, with the fusion of AgGaTe2 as a current augmenting layer the JSC gets a huge boost and is enhanced to 34.7 mA/cm2 with a PCE of 33.89%. These simulation findings unveil the potential of the proposed solar cell structure with CZTS as the absorber layer and AgGaTe2 as the current boosting layer in creating an environment-friendly, affordable and highly efficient thin film solar cell.

A simulation approach for investigating the performances of cadmium telluride solar cells using doping concentrations, carrier lifetimes, thickness of layers, and band gaps

Antimony doped tin oxide (ATO), as one kind of transparent conductive oxides (TCO), is applied as electrodes in thin film solar cells. On the basis of the traditional glass/TCO structure on top of amorphous silicon thin-film solar cells, graphene is introduced to form the glass/TCO/Graphene and the glass/Graphene/TCO layered structure, which is aimed at both enhancing the optical absorption of thin-film solar cells as an antireflection coating (ARC) and increasing the electrical conductivity as a TCO electrode. In this paper, SiO2/ATO/Graphene and SiO2/Graphene/ATO structure are selected for the optimal lighttrapping design by using differential evolution method. The effect of graphene is mainly investigated and the thickness of the layers of proposed structure is optimized to enhance the optical absorption of thin-film solar cells to the greatest degree. The theoretical calculation results clearly demonstrate that the proposed SiO2/ATO/Graphene layered structure is obviously superior to the SiO2/Graphene/ATO structure, and it can obtain a higher light-trapping enhancement in the whole visible and near-infrared wavelength range because of the graded refractive index distribution profile.

Photovoltaic cell or commonly known as solar cell is an electrical device used to convert energy from light directly into electricity using the photovoltaic effect. Solar cells are categorized into many types. Thin film solar cells from the second generation are mostly used and have gained enormous interest among the research community. Thin film solar cells have a few common layers that deposit on substrate. The layers are known as back contact, absorUer layer (p type), window layer (n-type), and front contact layer. Cadmium, Indium, Gallium, and Selenium (CIGS) used as the absorber layer in the solar cell have been proven to achieve high efficiency. However, it is a well- known fact that indium and selenide in the stated compound are rare earth (RE) matenals, expensive, and toxic. Therefore, it is a requirement to identify an alternate type of material to use for the aUsorber layer that outains high efficiency as well. In view of this, significant research has been reported with Copper, Zinc, Tin, and Sulphur (CZTS) used as the absorber layer. This material can be easily obtained and is low cost due to the abundant materials on earth and has a bandgap of 1.5 eV and absorption coefficient of >104. Commonly, the CZTS based thin film researches have been conducted on a rigid substrate such as soda lime glass and the layer will be deposited by a vacuum based process such as sputtering and evaporation. In view of identifying a new application of solar cell, in this study, a non-vacuum process was utilized to deposit the CZTS precursors on a flexible substrate. Fiber was used as a substrate for this study to develop the solar cell due to its flexibility which can be bent and rolled into a bulk that is able to reduce the usage of surface area and thus reduce the cost as well. The coated layers were characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM) to study the layer surface morphologies, grain sizes, and the roughness of the coated layer.

By using radio frequency plasma enhanced chemical vapour deposition (RF-PECVD) method (13.56 MHz) we have developed high quality wide band gap p-type hydrogenated amorphous silicon oxide (p-a-SiO:H) films having characteristics suitable for use as the window layer for single and multijunction amorphous silicon (a-Si) solar cells. The films have been characterized in detail. The p-a-SiO:H films having thickness ≥100 Å has photoconductivity (σph) one order of magnitude higher than that for p-type hydrogenated amorphous silicon carbide (p-a-SiC:H) films having similar band gap. However, at thickness ∼100 Å, required for window layer, the σph of p-a-SiO:H film is ∼102 times higher than that of p-a-SiC:H film. This difference in thickness dependence of σph has been attributed to the structural difference of the two types of window layers. We have fabricated single junction p-i-n structure a-Si solar cells on transparent conducting oxide (TCO) coated glass substrates with both p-a-SiO:H and p-a-SiC:H film as the window layer. In the former case the Fill Factor of the solar cell is higher by ∼10%. The improvement in Fill Factor is due to the higher σph of p-a-SiO:H resulting in lower series resistance.

Recently, plasmonics has been used to trap the light at nanoscale to improve the absorption in solar cells. In this study, we construct a silicon thin-film solar cell (TFSC) using finite-difference time-domain (FDTD) simulation. The TFSC solar cell was designed with TiO2 anti-reflection layer, aluminum (Al) as a reflective layer, and silicon (Si) as a absorption layer. The silver nanoparticles of 50 nm diameter and 400 nm separation are embedded on absorption layer. Optimizing the location of nanoparticle, light scattering efficiency and near-filled light concentration has been harnessed. The reflective Al layer reflect the light towards upper layer and increases the overall absorption. The proposed structure allows the sunlight to enter into the absorption layer at all directions, breaking the molecular bonding and releasing electrons. We determined the short-circuit current, fill factor, open-circuit voltage, absorption efficiency, and conversion efficiency of our proposed model. The simulation results reveals that, TFSC with embedded nanoparticle array, antireflection coating and reflective layer has higher short-circuit current of 23.98 mA/cm2, higher fill-factor of 0.84 and an efficiency of 12.3%.The proposed TFSC solar cell increases the absorption efficiency by 43.5% and conversion efficiency by 64.66% compared with conventional TFSC. The findings will be helpful to design more efficient and cost effective solar cell utilizing light-trapping mechanism of plasmonic nanoparticle of different size, shape, and geometry.

The effect of the deposition temperature of the buffer layer In2S3 on the band alignment of CZTS/In2S3 heterostructures and the solar cell performance have been investigated. The In2S3 films are prepared by thermal evaporation method at temperatures of 30, 100, 150, and 200 °C, respectively. By using x-ray photoelectron spectroscopy (XPS), the valence band offsets (VBO) are determined to be , , , and eV for the CZTS/In2S3 heterostructures deposited at 30, 100, 150, and 200 °C, respectively, and the corresponding conduction band offsets (CBO) are found to be , , , and eV, respectively. The XPS study also reveals that inter-diffusion of In and Cu occurs at the interface of the heterostructures, which is especially serious at 200 °C leading to large amount of interface defects or the formation of CuInS2 phase at the interface. The CZTS solar cell with the buffer layer In2S3 deposited at 150 °C shows the best performance due to the proper CBO value at the heterostructure interface and the improved crystal quality of In2S3 film induced by the appropriate deposition temperature. The device prepared at 100 °C presents the poorest performance owing to too high a value of CBO. It is demonstrated that the deposition temperature is a crucial parameter to control the quality of the solar cells.

An overview of the applications of porous silicon (PS) thin films, as antireflection coatings (ARC) in silicon solar cells and transducers in biosensors, is presented. The reflectance spectra of PS films have been compared with other conventional ARCs (such as SiNx TiO2/MgF2 and ZnS), and optimal PS ARC with minimum reflectance has been obtained. The implementation of PS into an industrially compatible screen-printed (SP) solar cell by both the electrochemical etching (ECE) and chemical etching (CE) methods are reviewed. Porous silicon films, formed via ECE for short anodization times, on textured n+ emitter ofc-Si solar cell having SP front and back contacts, lead to improvements in the performance of solar cells and demonstrate their viability in industrial applications.

Device optimization of CsPbI2Br-based inorganic perovskite solar cells using different charge transport layers via SCAPS-1D