Efficiency Of Silicon Solar Cells Research Articles

Effect of increasing etching time on the efficiency of porous silicon solar cells

In this work, p-type silicon wafers were electrochemically etched to create nanocrystalline silicon (porous silicon (PS)) films. Different etching periods (5, 10, 15, and 20 minutes) were investigated to see how they affected the development of a nanosized pore array with a constant etching current density (10 mA/cm2). To prevent oxidation, PS samples were stored in methanol after preparation. PS is characterized by X-ray diffraction (XRD), and atomic force microscopy (AFM). At varied etching times (5, 10, 15, and 20 min), the crystallite size as determined by XRD was equal to (66.39, 88.13, 31.2, and 21.21) nm, respectively. The nanometric size was verified via AFM. The porosity of PS increased as the etching time increased; the maximum value was obtained at a 20-minute etching time. The C-V characteristic of PS/Si heterojunction describes control factors like built-in potential (Vbi) and the kind of connection, a linear relationship of 1/C2 with bias voltage indicating that the junction is an abrupt type. Vbi was calculated for PS/p-Si/Al heterojunction at different etching times, and it was between (1.1-1.8) volt. I-V characteristics under illumination showed an enhancement in the efficiency of the PS/Si/Al solar cells. The maximum value of the solar cell efficiency was 6.79% occurs at 15 min time of etching.

A Deep-Red Emission Phosphor Y2SrAl4SiO12:Ce3+, Cr3+ and Its Utilization in Polycrystalline Silicon Solar Cells

The power conversion efficiency (PCE) of crystalline silicon solar cells has reached a bottleneck. Further improving the PCE is an important current research topic. This Letter reports a new phosphor Y2SrAl4SiO12:Ce3+, Cr3+. Under the excitation in the wavelength range of 320-650 nm, the phosphor Y2SrAl4SiO12:Ce3+, Cr3+ exhibits a deep-red emission in the 500-800 nm range. Due to the energy transfer from Ce3+ to Cr3+, the luminescence intensity of Cr3+ is further enhanced. This matches well with the spectrum of silicon solar cells. Because of the powerful absorption and high internal quantum efficiency, Y2SrAl4SiO12:Ce3+, Cr3+ was used to prepare energy down-conversion (EDC) films. By applying the EDC film on the surface of silicon solar cells, the relative PCE increases by 2.018%. These results indicate that Y2SrAl4SiO12:Ce3+, Cr3+ is an excellent deep-red garnet structured phosphor and furthermore has a positive effect on the enhancement of the PCE of solar cells.

Study of the Enhanced Efficiency of Crystalline Silicon Solar Cells by Optimizing Anti Reflecting Coating using PC1D Simulation

In this paper, simulation of a mono crystalline silicon solar cell was done using PC1D software. The impact of different solar cell parameters, with their effects on power and efficiency, has been investigated. It is seen that the textured surface reduces reflection and increases the efficiency of the solar cell at least 2–3%. From the simulation, it is seen that the optimum value of p-type doping concentration 1 × 10^16 cm^−3, n-type doping concentration 5 × 10^18 cm with pyramid height of 2–3 μm and equal angles of 54.74 degrees produces the best result in simulation. An anti-reflective coating with a refractive index of 1.38 and a thickness of 84 nm is considered optimal. By optimizing the effective parameters, a solar cell with an efficiency of 24.45% was achieved through simulation. For a p-type mono crystalline silicon wafer, with an area of 10 × 10 cm^2 and a thickness of 200 μm, initial simulation shows a 24.45% efficient solar cell.

Перспективный путь повышения эффективности кремниевых солнечных элементов --- введение нитевидных кристаллов с p-n-переходом

A new approach to increasing the efficiency of silicon solar cells (SCs) is presented, which consists in the creation of surface light-trapping structures with a high antireflection ability in the form of systems of pointed whiskers (NCs) with coaxial p–n junctions. The coaxial geometry of the p–n junction is justified in terms of the efficiency of collection and separation of minority charge carriers (NCCs) due to the built-in electric field across the junction. Received solar cells with improved photoelectric characteristics and an efficiency factor (COP) of 20.43%.

A promising way to improve the efficiency of silicon solar elements --- introduction of whiskers with p-n junction

A new approach to increasing the efficiency of silicon solar cells (SCs) is presented, which consists in the creation of surface light-trapping structures with a high antireflection ability in the form of systems of pointed whiskers (NCs) with coaxial p-n junctions. The coaxial geometry of the p-n junction is justified in terms of the efficiency of collection and separation of minority charge carriers (NCCs) due to the built-in electric field across the junction. Received solar cells with improved photoelectric characteristics and an efficiency factor (COP) of 20.43%. Keywords: solar cell, light absorption, p-n junction, silicon.

SiNx and AlOx Nanolayers in Hole Selective Passivating Contacts for High Efficiency Silicon Solar Cells

The recombination of photogenerated charge carriers at metal-semiconductor interfaces remains a major source of efficiency loss in photovoltaic cells. Here, we present SiN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> and AlO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> nanolayers as promising interface dielectrics to enable high efficiency hole selective passivating contacts. It is demonstrated that SiN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> deposited via direct plasma enhanced chemical vapour deposition can be grown controllably at thicknesses of 2 nm. The valence band offsets between crystalline silicon and ultrathin AlO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> and SiN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> nanolayers are measured as 3.5 and 1.4 eV, respectively. This predicts a larger tunnelling current for holes, compared to SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> used typically. Resistivity measurements show that SiN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> and AlO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> nanolayers have lower contact resistivities compared to SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> , with values as low as 100 mΩ·cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . Analysis of the current transport mechanisms confirmed that tunnelling dominates the conduction through SiN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> , while a mixture of tunnelling and pinholes are present in the AlO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> structure. Lifetime measurements gave initial indications of the passivation quality of the films, with just 10 cycles of AlO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> achieving 260 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">μ</i> s after annealing and 1.9 ms with extrinsic field effect passivation added. Finally, the intrinsic built-in charge in the dielectrics was determined using surface photovoltage measurements and simulations are used to estimate the influence of nanolayer built-in charge in both poly-Si and dopant-free passivating contacts to enable future high efficiency solar cells.

Modulation of the TCO/MoOx Front Contact Enables &gt;21% High-Efficiency Dopant-Free Silicon Solar Cells

Highly efficient dopant-free silicon solar cell requires effective electron- and hole-selective contacts. We have recently reported a remarkable efficiency of 21.3% for dopant-free silicon solar cells with a low work function and transparent and conductive MgFxOy electron extraction. The transparent conductive oxide (TCO) films and molybdenum oxide (MoOx) front hole contact also play significant roles in the high efficiency of dopant-free solar cells. In this study, zinc-doped indium oxide (IZO), tin-doped indium oxide (ITO), and titanium-doped indium oxide (ITiO) have been deposited via magnetron sputtering at room temperature. The work function and optoelectrical properties of TCO films and energy band bending together with the MoOx layer are investigated. The impact of this band bending on the photoelectrical performances of devices is analyzed in detail as a function of the MoOx/TCO work function mismatch. The optimized IZO film presents the highest work function (5.21 eV) and conductivity (2140 S/cm), resulting in reduced barrier height at the MoOx/TCO interface and enhanced hole-selective transport. The light-soaking treatment is introduced to repair the sputtered damage during the IZO deposition. Finally, an impressive cell efficiency of 21.0%, together with Voc, FF, and Jsc of 712.4 mV, 76.4%, and 38.6 mA/cm2, respectively, shows great potential and provides an effective solution to obtain highly efficient dopant-free silicon solar cells.

Silicon–Hydrogen Bonding Configuration Modified by Layer Stacking Sequence in Silicon Heterojunction Solar Cells

Recent improvements in highly efficient crystalline silicon (c-Si) solar cells have relied on surface passivation. Hydrogen plays a crucial role in the surface passivation of silicon heterojunction (SHJ) solar cells because Si–H bonds passivate dangling bonds in amorphous silicon and on the c-Si surface. In this work, we demonstrate that the Si–H bonding configuration is modified by layer stacking sequence for SHJs. The quality of surface passivation strongly correlates with low-temperature hydrogen effusion from the SHJ structure. Our results show that the deposition of doped layers on intrinsic amorphous silicon supplies additional hydrogen to the amorphous/crystalline heterostructure. Moreover, the deposition of a p-layer modifies the microstructure of the intrinsic layer underneath, whereas depositing an n-layer does not induce structural changes. We suggest that the low-temperature hydrogen effusion characteristics can be used as a sensitive indicator for examining the passivation quality of SHJ solar cells.

Smart Solar‐Panel Umbrella toward High‐Efficient Hybrid Solar and Rain Energy Harvesting

Solar photovoltaic power generation technology is the top priority of the global energy development strategy. Although the photoelectric conversion efficiency of crystalline silicon solar cells is as high as 33.7%, the power generation efficiency is relatively low or even unable to generate power normally under low‐light environments such as rainy weather and a cloudy day. Herein, a smart solar panel umbrella system with an auto open and close function is realized by integrating a polysilicon solar cell module and an interdigitated electrode structure triboelectric nanogenerator (IDE–TENG) toward hybrid solar and rain energy harvesting. The output performances of the IDE–TENG are systematically investigated and optimized by regulating the dielectric thickness, inclination angle of IDE–TENG, and various drip types. On this basis, combined with the solar module, the function of auto open and close for the smart solar panel system is realized by a 32‐bit microcontroller and a raindrop sensor, which can be automatically switched as the weather changes and maintain high power conversion efficiency of 19.61% of the solar cell. This smart solar panel umbrella system can be used as a self‐powered supply for all‐weather landscape lighting to save the utilization of fossil energy and contribute in the realization of carbon neutrality.

Photoresist Microlens Arrays Fabricated by Nanoimprint Technique to Improve the Photoelectric Conversion Efficiency of Solar Cells

Silicon solar cells have the advantages of non-toxicity, reliability, low price, and stability. Microlens arrays (MLAs) are widely used in solar cells to improve photoelectrical conversion efficiency (PCE). In this research, different MLAs mold was designed by a method of thermal reflow. Then the photoresist film MLAs structure was replicated on the surface of silicon solar cells through UV nanoimprint technology. The optical transmission and surface morphology of these photoresist films were respectively measured by using a UV spectrometer and an atomic force microscope. The surface morphology and imaging capabilities of photoresist film MLAs were respectively measured by using a scanning electron microscope and optical microscope. Finally, the photovoltaic performance of the silicon solar cell with the photoresist film MLAs was investigated, and the PCE value of the silicon solar cell improved from 11.53% for the sample without MLAs to 13.19% for the sample with the square MLAs and the PCE improvement is about 14.40%. All these results above show that the photoresist film MLAs can significantly improve the efficiency of silicon solar cells and have great application potential in the field of solar cells.

Past, Present, and Future Outlook for Edge Isolation Processes in Highly Efficient Silicon Solar Cell Manufacturing

This work highlights present research and mass production results of wet‐chemical solutions for industrial edge isolation of silicon solar cells, aiming for a reduction of nitric acid consumption and production costs as well as a simultaneous increase in efficiency. All processes are applied to either industrially passivated emitter and rear contact (PERC) or tunnel oxide‐passivated contact (TOPCon) solar cells. Herein, a review of different edge isolation techniques in the history of silicon solar cell processing is presented. Subsequently, novel wet‐chemical approaches are focused on, namely 1) HNO3‐reduced edge isolation (InOxSide Fusion), 2) HNO3‐free edge isolation (InOxSide Blue), and 3) batch cluster solution—a combination of an acidic inline and an alkaline batch tool for emitter edge isolation of PERC and TOPCon solar cells. For each of the approaches, cell results and total cost of ownership estimations are presented. Based on all findings, a comprehensive discussion between inline versus batch‐cluster processing is presented. All investigations are performed on industrial equipment, wafer sizes, and a solar cell efficiency level of above 23%.

Interface Tuning through the MoO3 Additive in Al Paste to Enhance the Performance of Crystalline Silicon Solar Cells

The efficiency of silicon solar cells is largely affected by the quality of the front and back metallic contacts. In this work, MoO3 is added to the Al paste for the back contact of crystalline silicon solar cells. The MoO3 additive lowers the series resistance of the solar cell from 4.1 to 3.5 mΩ and increases the photoelectric conversion efficiency from 19.26 to 19.54%. We identify that the thermite reaction between MoO3 and Al takes place at about 800 °C and metallic Mo diffuses into the Al–Si solid layer, decreasing the barrier height between Al and Si and lowering the contact resistance. This work demonstrates an approach by optimizing the aluminum-back surface field (Al-BSF) in the back metallic contact of crystalline silicon solar cells to enhance the performance of the cell.

Influence of Silicon Dioxide-Titanium Dioxide Antireflective Electrosprayed Coatings on Multicrystalline Silicon Cells

This research work primarily focuses on enhancing the power conversion efficiency (PCE) of polycrystalline silicon solar cells by using a single-layer and a double-layered antireflection coating deposited through the electrospraying technique. The usage of titanium dioxide and silicon dioxide as antireflection coating materials has shown a significant increase in the optical and electrical properties of solar cells under open and controlled light sources. The sample with TiO2 as a base layer and SiO2 as the top layer (sample B-IV) exhibited a maximum PCE of 18.90% in direct sunlight and 21.19% in a neodymium setup with cell temperatures of 40°C and 52.1°C, respectively. Sample B-IV has also shown the lowest resistivity of 3.1 × 10−3 Ω·cm among the coated samples. Also, an increase of 11.6% light transmittance and a reduction of 9.6% light reflectance were exerted by sample B-IV. The results obtained from different analysis proves that TiO2/SiO2 was an appropriate antireflection coating material for enhancing the PCE of the polycrystalline silicon solar cell.

Experimental investigation and theoretical modeling of textured silicon solar cells with rear metallization

Crystalline Silicon (c-Si) remains a dominant photovoltaic material in solar cell industry. Currently, scientific and technological advances enable producing the c-Si solar cells (SCs) efficiency close to the fundamental limit. Therefore, combining the experimental results and those of modeling becomes crucial to further progress in improving the efficiency and reducing the cost of photovoltaic systems. We carried out the experimental characterization of the highly-efficient c-Si SCs and compared with the results of modeling. For this purpose, we developed and applied to the samples under investigation the improved theoretical model to optimize characteristics of highly efficient textured solar cells. The model accounts for all recombination mechanisms, including nonradiative exciton recombination by the Auger mechanism via a deep recombination centers and recombination in the space-charge region. To compare the theoretical results with those of experiments, we proposed empirical formula for the external quantum efficiency (EQE), which describes its experimental spectral dependence near the long-wave absorption edge. The proposed approach allows modeling of the short-circuit current and photoconversion efficiency in the textured crystalline silicon solar cells. It has been ascertained that the dependences of the short-circuit current on the open-circuit voltage and the dark current on the applied voltage at V &lt; 0.6 V coincide with each other. The theoretical results, as compared to the experimental ones, allowed us to validate the developed formalism, and were used to optimize the key parameters of SCs, such as the base thickness, doping level and others. In this work, we have further generalized and refined the analytical approach proposed and used by us earlier to analyze high-efficiency solar cells and model their characteristics.

Spray-coated SiO2/PECVD SiN[formula omitted] stack for the passivation of n[formula omitted] emitter of p-type Si solar cell

Inefficient passivation of phosphorous diffused emitter is one of the limiting factors contributing to lower efficiency in advanced p-type silicon solar cells. Stack of SiO2 and SiNx with the former as an intermediate layer beneath SiNx provides better emitter passivation in comparison to SiNx film alone. Thermal oxide is reported to provide the best passivation, but it is not industrially viable. We demonstrate spray SiO2/SiNx as a viable alternative to thermal SiO2/SiNx stack. A few nanometer thin (∼6.1 nm) spray SiO2 film was first time demonstrated on micrometer sized textured pyramid with full coverage over an entire deposited area. The passivation of symmetrical (n+-p-n+) structure shows iVoc∼660 mV and passivation uniformity over the entire wafer area for both the stacks. Voc∼630 mV is achieved on cells with spray and thermal SiO2 as a passivating layer. Similar front passivation is further verified by overlapping IQE in the shorter wavelength range. Therefore, incorporating SiO2 film deposited via an industrially viable spray-coating process as a passivating layer at the front provides overall cell performance similar to the thermally grown SiO2.

Size effect of gold nanoparticles on optical and electrical properties of plasmonic silicon solar cell

One of important tasks of the day is increasing the efficiency and decreasing the cost of the silicon solar cells. There is method of introducing of metal nanoparticles into solar cells to improve its absorption and reduce transmission as well as reflection coefficients. When metal nanoparticles are introduced into silicon solar cell, nanoplasmonic effect will occur. Nanoplasmonic effect lead to modification of light spectrum and generation of extra hot electrons. Nano-plasmonic effect strongly depends on size of nanoparticles. Therefore, in this paper, effect of gold nanoparticles size on properties of silicon solar cell has been studied by using simulation. Gold nanoparticles with sizes of 4 nm, 6 nm, 9 nm, 11 nm and 21 nm have been input into emitter region of silicon solar cell in order to use both of nanoplasmonic-electric and nanoplasmonic-optic effects for enhancing efficiency of silicon solar cell. Open circuit voltage didn't change when size of nanoparticles has been changed from 4 nm to 11 nm. It dropped by 0.017 V when size of nanoparticles was 21 nm. Short circuit current has been maximum 6.7 mA/cm2 at nanoparticle size of 11 nm and minimum 3.1 mA/cm2 at nanoparticle size of 21 nm. It has been found from obtained results that gold nanoparticle with size of 11 nm affected significantly on properties of silicon solar cell. Besides, thickness of silicon solar cell can be decreased without dropping of efficiency by introducing gold nanoparticles. Because, main part of photons is absorbed near to metal nanoparticles inputted region.

Thermal annealing effects on tunnel oxide passivated hole contacts for high-efficiency crystalline silicon solar cells

Tunnel oxide passivated contacts (TOPCon) embedding a thin oxide layer between polysilicon and base crystalline silicon have shown great potential in the development of solar cells with high conversion efficiency. In this study, we investigate the formation mechanism of hole-carrier selective contacts with TOPCon structure on n-type crystalline silicon wafers. We explore the thermal annealing effects on the passivation properties in terms of the stability of the thermally-formed silicon oxide layer and the deposition conditions of boron-doped polysilicon. To understand the underlying principle of the passivation properties, the active dopant in-diffusion profiles following the thermal annealing are investigated, combined with an analysis of the microscopic structure. Based on PC1D simulation, we find that shallow in-diffusion of boron across a robust tunnel oxide forms a p–n junction and improves the passivation properties. Our findings can provide a pathway to understanding and designing high-quality hole-selective contacts based on the TOPCon structure for the development of highly efficient crystalline silicon solar cells.

Performance Enhancement of Crystal Silicon Solar Cell by a CsPbBr3–Cs4PbBr6 Perovskite Quantum Dot @ZnO/Ethylene Vinyl Acetate Copolymer Downshifting Composite Film

Crystal silicon solar cells being the most successful photovoltaic devices have prevailed in the energy market for decades. To further improve the device performance, photon management is necessary. Herein, a CsPbBr3–Cs4PbBr6 perovskite quantum dot@ZnO/ethylene vinyl acetate copolymer downshifting composite film is coated on the silicon solar cell. This downshifting composite film helps to convert high‐energy (UV‐blue) photons to relatively low‐energy photons with a wavelength at about 500 nm, which possess higher sensitivity in silicon solar cells. The effects of tetra‐n‐heptylammonium bromide and Zn(C2H5)2 on composition, optical and luminescence properties of perovskite quantum dots are thoroughly investigated, and a clean quantum dot solution with strong luminescent intensity can be obtained. The perovskite quantum dot@ZnO/ethylene vinyl acetate composite film absolutely improves the efficiency of silicon solar cells by 1.18%. The value is much higher than pure ethylene vinyl acetate (0.42%) and composite film without ZnO (0.57%). Moreover, ZnO inclusion can inhibit Cs and Pb leakage and maintain the device working stability, which is helpful for their commercial application in the future. This study further reveals that the enhancement lies in carrier relaxation energy loss reduction. Herein, a low‐cost downshifting composite film with excellent environmental stability for silicon solar cells applications is proposed.

Pulsed laser deposition of ZnO and MoO3 as reflection prohibitors on photovoltaic cell substrate to enhance the efficiency

With the ever-growing demand for conventional fuels, the improvement in the efficiency of the photovoltaic system is the need of the hour. Antireflection coatings enhance the availability of solar power by reducing the percentage of light reflected. A new coating has been developed to improve the solar cell's overall efficiency. This study focuses on enhancing the efficiency of the monocrystalline solar cell when a coating of ZnO-MoO3 is applied at a certain thickness. A layer of ZnO followed by MoO3 is deposited on a Silicon solar cell substrate using a Pulsed Laser Deposition process. Due to the transmissivity d between the two materials, they act as excellent antireflection coating. The layer thickness has been engineered to lie in the maximum absorption spectrum of monocrystalline silicon solar cells, which is between 400 and 800 nanometers. Based on the calculation of transmissivities for a given layer thickness of coating material, the coating has been done, and the efficiencies of the coated specimen were compared with the uncoated solar cell. The percentage improvement in the electrical efficiency of a single crystalline silicon solar cell with an anti-reflection coating at 1059 W/m2 is about 35.7%. Among the available antireflection coating materials, the combination that provides better efficiency when coated on top of a solar cell is hard to find. This anti-reflection coating could be a better solution to enhance the overall efficiency of the single crystalline silicon solar cell. Although ZnO and MoO3 coatings have been investigated separately for improvement in solar cell efficiency with varying levels of success, the hybrid coating of ZnO/MoO3 with a performance enhancement of 35.7% is a great leap.

Prediction of the performance of a solar PV system in Baghdad, Iraq

The world is actively seeking alternatives to traditional energy sources amid increasing demand for energy as a result of population growth, the development of technologies, and the environmental pollution caused by traditional energy sources and their tendency to deplete. Renewable energy sources are one of the most promising sources, mainly solar energy, which is the source of most of these sources. The goal of this work is to analyze data collected by the Al-Rashidiya meteorological station to predict the performance of solar PV modules (NT-R0E3E-SHARP) in this geographical area. Depending on the data from the Al-Rashidiya meteorological station, each of the tilted global solar radiation, cell temperature, output power, and electric conversion efficiency was calculated by using the PV model. The results indicated that the annual solar radiation incident in Baghdad with the horizontal plane was 1834kWh/m2/year with an annual peak sun hours (solar fuel) of 5, and the degradation percentage in the electrical conversion efficiency of monocrystalline silicon solar cells ranged between 2% in winter to 11% in summer. From the results of the present work, it can be concluded that Baghdad’s geographical area and surroundings are promising for investing in solar energy to produce electricity.