A freeware program for precise optical analysis of the front surface of a solar cell

Due to global population growth and industrial development, there is a rising demand for energy. It is desired that this demand is met in a cleaner and more sustainable way. Among the various renewable energy sources, solar power is experiencing remarkable growth throughout the world. To ensure that solar power can be a sustainable solution for the future energy demands, intensive research is being conducted to make solar cells more efficient and thereby reduce the cost of solar energy. Solar cells have metallization patterns on the front side to collect current generated in the semiconductor layer. The performance of a solar cell significantly depends on the amount of electrode material used for metallization, and the pattern in which it is deposited. There exist several optimization approaches to optimize the metallization distribution on the front surface of solar cells. However, due to the numerical simplifications associated with these methods, only limited gains in power output are observed. Moreover, the applicability of these methods is historically restricted to rectangular or circular domains. There has recently been a drive towards increased freeform photovoltaic installations. Given that these shapes can be very arbitrary, the optimal metallization patterns for such geometries can be expected to be complex, and the traditional methods cannot be used to design them.

Cost-effective and lightweight solar cells are currently demanded in strategic fields such as space applications or integrated-wearable devices. A reduction of the active layer thickness, producing thin-film devices, has been a traditional solution to accomplish both requirements. However, this solution also reduces the efficiency of the device. For this reason, alternative strategies are being proposed. In this work, light trapping effects of an array of semiconductor nanoparticles located on the top surface of a thin-film GaAs solar cell are investigated to improve the optical absorption and current density in active layer, under the standard AM-1.5 solar spectrum. The numerical results are compared with other previous proposals such as an aluminum nanoparticle array, as well as conventional solar cells with and without a standard anti-reflective coating (ARC). The inclusion of semiconductor nanoparticles (NPs) shows an improved response of the solar cells at different angles of incidence in comparison to solar cell with an ARC. Furthermore, the efficiency increases a 10% respect to the aluminum nanoparticles (NPs) architecture, and a 21% and a 30% respect to solar cells with and without ARC, respectively.

Solar cells can transform light energy into electrical energy, possibly removing the need for fossil fuel energy resources. Reflection loss in solar cells is a factor contributing to diminished power conversion efficiency, which can be solved through using antireflective coatings on the cell surface. The present research primarily focuses on the development and application of antireflection coatings on the top surface of silicon solar cells. Sb2Se3 was deposited over multi-crystalline Si cells with different durations from 15 to 60 minutes. The influence of thin film Sb2Se3 coated cells was investigated through optical, current, voltage and thermal study. The ideal thickness of the Sb2Se3 coating was determined to be 1.336 µm for SB3 sample using FESEM. The lowest optical reflectance of 5.8% and highest absorbance of 93.4% was reached after 45 minutes of coating (SB3) across the 300 to 1200 nm wavelength band. The minimum electrical resistivity of a 45-minute coated Sb2Se3 sample was determined as 5.09×10−3 Ω-cm. The improved power conversion efficiency of Sb2Se3 coated solar cell under open sunlight setting was increased from 15.31 to 21.18% particularly for SB3 solar cell sample, which optimize maximum transfer of incident photons into the solar cell. From the observed results, it indicates that Sb2Se3 nanocoating has identified to be ideal antireflection coating material for polycrystalline silicon solar cells.

An efficient optical antireflective (AR) structure plays a vital role in high‐performance thin‐film solar cells. Here, we design a surface relief AR structure consisting of a two‐dimensional (2D) array of a subwavelength ring and pillar‐shaped feature, capable of suppressing optical reflection over a wide spectral window of the solar spectrum. Our simulations show that the weighted average reflectance of the subwavelength AR structure is as low as 4.2% in the 400–1100 nm spectral range in the normal incidence condition and almost 10‐fold reduction compared with a bare silicon surface. When placed on the front side of a simple Si thin‐film photovoltaic solar cell, this subwavelength AR structure leads to an improved light absorption with simulated results showing an increase of 53% short‐circuit current compared to a flat solar cell. Besides, our simulations show that this AR structure could, in principle, perform well against reasonable fabrication errors.

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.

Investigation on antireflection coatings for Al:ZnO in silicon thin-film solar cells

Dielectric colloidal nanospheres (NSs) are promising candidates for light management in photonic devices such as solar cells (SCs). NS arrays can direct the broad incident solar radiation into a set of tighter foci, at which light intensity becomes considerably concentrated, enabling higher photovoltaic conversion efficiency. Furthermore, the NS arrays acting as an effective medium on the SC surface can reduce reflectance and facilitate improved forward scattering. Therefore, uniform arrays of NSs located on top of the SC can behave as antireflection coatings or as microlenses, which can be regarded as a surface distributed light concentrator within the framework of concentrated photovoltaics. Fabrication of NS‐based light‐trapping structures is low‐cost and less complicated than common alternatives such as vacuum evaporated multilayer antireflection coatings. In this work, experimental demonstration and computational confirmation on the shape adjustment of such NS structures for improved light harvesting and efficiency enhancement in Si SCs are studied. The light conversion efficiency of Si solar cells is shown to improve by more than 27% with shape adjustment of NS arrays.

In this work, a numerical assessment of the optoelectrical properties of the ZnO–ZnSe–CdSe heterojunction for a thin and cost-effective solar cell was made by using the PC1D simulation software. The photovoltaic (PV) properties have been optimized by varying thicknesses of the absorber layer of the p-CdSe layer, the window layer of n-ZnSe, and the antireflection coating (ARC) layer of ZnO, a transparent conductive oxide with enhanced light trapping, and wide bandgap engineering. There is a positive conduction band offset (CBO) of ΔEc = 0.25 eV and a negative valence band offset (VBO) of ΔEv = 1.2 − 2.16 = − 0.96 eV. The positive CBO prevents the flow of electrons from the CdSe to the ZnSe layer. Further, the impact of doping concentration on the performance of solar cells has been analyzed. The simulation results reveal the increase in the efficiency of solar cells by adding an ARC. The rapid and sharp increase in the efficiency with the thickness of the window layer beyond 80 nm is interesting, unusual, and unconventional due to the combined effect of morphology and electronics on a macro-to-micro scale. The thin-film solar cell with the structure of ZnO/ZnSe/CdSe exhibited a high efficiency of 11.98% with short-circuit current (Isc) = 1.72 A, open-circuit voltage (Voc) = 0.81 V and fill factor (FF) = 90.8% at an optimized thickness of 2 μm absorber layer, 50 nm window layer, and 78 nm ARC layer. The EQE of solar cells has been observed at about 90% at a particular wavelength at 470 nm (visible light range). Around 12% of efficiency from such a thin-layered solar cell is highly applicable.

Owing to small size effect and large surface area, silver nanoparticles (Ag NPs) exhibit special physical properties and are widely used in different applications. One of the significant applications is that Ag NPs can be coated on the glass surface of solar cell to increase the light-harvesting efficiency of solar cell due to the plasmonic resonance and scattering effect. In this study, Ag NPs used for the coating of solar cells were synthesized via a chemical reduction method. The effect of the concentration of sodium borohydride (NaBH4) as reducing agent and 1-dodecanethiol (DDT) as capping agent on the size and shape of Ag NPs synthesized have been investigated. The synthesized Ag NPs were characterized using UV–vis spectroscopy, X-ray diffraction, energy-dispersive X-ray spectrometry and ATR-FTIR spectroscopy; while the particle size, morphology and topology of Ag NPs were examined by scanning electron microscopy and atomic force microscopy. By coating the glass surface of amorphous silicon solar cells with a uniform array of Ag NPs with the particle size of > 350 nm, a power conversion efficiency (PCE) enhancement of approximately 41% has been achieved. (3-mercaptopropyl) trimethoxysilane (MPTMS) was used as the adhesion promoter to anchor Ag NPs on the silicon surface of solar cells. With 7% of MPTMS, the array of Ag NPs formed on the glass surface was found being the most evenly distributed with a densely packed surface coverage, which resulted in 46% of PCE enhancement of the silicon solar cells.

Transparent ZnO thin-films are prepared using the RF magnetron sputtering and spray pyrolysis techniques on the glass substrates. Reflectance spectra and thin films heights are measured using spectrophotometer and stylus surface profiler, respectively. Measured optical data is used for investigating the effect of the ZnO prepared by above two processes on the performance of Cu2ZnSnS4 (CZTS) thin films solar cell (TFSC). One dimensional simulation approach is considered using the simulation program, SCAPS. External quantum efficiency and J-V characteristics of CZTS TFSC is simulated on the basis of optical reflectance data of ZnO films with and without ZnO thin-films as antireflection coating (ARC). Study shows that ARC coated CZTS TFSC provides a better fill factor (FF) as compared to other ARC material such as MgF2. Sprayed ZnO thin-films as ARC show comparable performance with the sputtered samples.

An attempt is made to assess the accuracy of the simplifying assumption of total retransmission of light inside the escape or loss cone which is made in many models of optical confinement in thin-film silicon solar cells. A closed form expression is derived for the absorption enhancement factor as a function of the refractive index in the low-absorption limit for a thin-film cell with a flat front surface and a lambertian back reflector. Numerical calculations are carried out to investigate similar systems with antireflection coatings, and the investigation of cells with a textured front surface is achieved using a modified version of the existing ray tracing computer simulation program TEXTURE.

The main objectives was to investigate and enhance the short circuit current density, J sc and also to improve the efficiency of silicon solar cel l by fabricating a layer of silicon dioxide (SiO 2) and silicon nitride (Si 3N4) coatings on silicon solar cell. This fabrication carried out on high temperature during annealing process from 800-1050°C and variable thickness of antireflection coating (ARC) layer from 50-90 nm thick. The photovoltaic propert ies of Si 3N4 layer have been compared with SiO 2 layer to determine which material is suitable in fa bricating single layer ARC. Solar cell simulation could be useful for time saving and cost consumptio n. Problem statement: The Silvaco software is not widely used in designing the 2D solar cell devi ces because there are lots of 1D, 2D and 3D- simulation beside Silvaco software such as MicroTec, SCAPS-1D. Approach: The silicon dioxide (SiO 2) and silicon nitride (Si 3N4) coating have been modeled and fabricated on silic on solar cell by using Silvaco software packaging. Results: For SiO 2 results, the FF value is approximately 0.758 and η maximum 9.43%. In annealing process, the temperature becomes higher resulted increasing of pn junction depth. However, not to V oc and Jsc values, both parameters were slowly decreased when temperature increased. Meanwhile, when the thickness of SiO 2 layer is increased, the parameters of pn junction depth, J sc , Voc , FF and η were decreased slowly. As for Si 3N4 result, the calculated FF approximately 0.758 and η maximum is 9.57%. During annealing process, the temperature increasing constantly follows the increasing of pn junction de pth and Jsc , meanwhile the Voc is decreased slowly. In variable Si 3N4 thickness simulation, the output parameters of pn junction depth, J sc , Voc , FF and η were decreased when the thickness increased 10 nm each simulation. Conclusion: The optimum temperature during annealing process for SiO 2 is 950 °C, while for Si 3N4 is 1050 °C. For the thickness analysis, the optimum ARC thickness for SiO 2 and Si 3N4 layer is 50 nm both.

Broadband light absorption enhancement in a–Si:H ultrathin film solar cells with nanophotonic light trapping structures

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.

The issue of potential-induced degradation (PID) has gained more concerns due to causing the catastrophic failures in photovoltaic (PV) modules. One of the approaches to diminish PID is to modify the anti-reflection coating (ARC) layer upon the front surface of crystalline silicon solar cells. Here, we focus on the modification of ARC films to realize PID-free step-by-step through three delicate experiments. Firstly, the ARC films deposited by direct plasma enhanced chemical vapor deposition (PECVD) and by indirect PECVD were investigated. The results showed that the efficiency degradation of solar cells by indirect PECVD method is up to −33.82%, which is out of the IEC 62804 standard and is significantly more severe than by the direct PECVD method (−0.82%). Next, the performance of PID-resist for the solar cell via indirect PECVD was improved significantly (PID reduced from −31.82% to −2.79%) by a pre-oxidation step, which not only meets the standard but also has higher throughput than direct PECVD. Lastly, we applied a novel PECVD technology, called the pulsed-plasma (PP) PECVD method, to deal with the PID issue. The results of the HF-etching rate test and FTIR measurement indicated the films deposited by PP PECVD have higher potential against PID in consideration of less oxygen content in this film. That demonstrated the film properties were changed by applied a new control of freedom, i.e., PP method. In addition, the 96 h PID result of the integrated PP method was only −2.07%, which was comparable to that of the integrated traditional CP method. In summary, we proposed three effective or potential approaches to eliminate the PID issue, and all approaches satisfied the IEC 62804 standard of less than 5% power loss in PV modules.