Several investigations have been carried out to understand the role of these embedded nanoparticles and potential to improve performance 9-11. We have done several modeling for cases of MNPs that were moved from the top of the intrinsic layer to its bottom, however, the solar cell efficiency still dropped even further to 2.55% 17, which is related to effect of defects. Amorphous hydrogenated silicon carbide (a-SiC : H) films are widely used as active window layers to enhance the optical transparency by widening the bandgap of the material in both amorphous–amorphous and amorphous–crystalline silicon solar cells while a-SiGe : H is used as an absorber layer in single [3, 18] or double or triple junction solar cells [3, 9, 12, 18]. Defects would spread around embedded MNPs causing loss that would increase even further with higher defect density. Power losses, quantum efficiencies, and short-circuit currents of different layers of the cell are analyzed. Since during the fabrication process there is no control on the shape of silver NPs, then only two variables left for tuning thin film plasmon solar cells. The effect of placing MNPs at alternative locations (front, middle, and back of the P‐I‐N solar cell) to maximize the photocurrent generation will be discussed in section II. If efficiencies of 10% can be reached on large area thin film amorphous silicon cells on inexpensive substrates, then this would be the best approach to … These enhancement methods are based on increasing the optical path length and embedding scatterers within cells. The boundary conditions, and the excitation in a 3D structure of the solar cell. It is certainly not recommended to embed large MNPs inside the active region, because it can cause a large amount of optical loss for the whole system. The dimensions of nanoparticles affect the absorption and efficiency of solar cells. Extinction coefficient of amorphous silicon. Hence, better manufacturing techniques need to be developed to reduce both defects and recombination, and to direct more light to the depleted region. At the same time, the size of the grains is correlated with the thickness of the thin film TCO layer, where a thinner film may have less surface roughness 24-26. Advantages. [1] Oerelikon set the world record for stable amorphous solar cells to above 10% in 2009. Authors contributed equally to this work. Presence of defects has resulted in a considerable optical loss around the MNPs. Working off-campus? 5A). Amorphous silicon panels are formed by depositing a thin layer of silicon material on a … Intuitively, the high‐frequency spectrum of light is mostly absorbed within the top layers. This success establishes the logistics to extrapolate models that include MNPs effects and the impact of their size, shape, and location of the device layers on solar cell efficiency. A maximum short-circuit current density of 15.32 mA/cm2 and an energy conversion efficiency of 11.3% were obtained for the optically optimized cell which is the best in class amorphous solar cell. Abstract An amorphous silicon solar cell on a periodic nanocone back reflector with a high 9.7% initial conversion efficiency is presented. Office of Energy Efficiency & Renewable Energy NREL is operated by Midwest Research Institute Battelle Contract No. It is suggested that small MNPs to be placed between the transparent electrode and the highly doped semiconductor at the top layer side, instead of inside the P+ region for ease of fabrication process. The highest efficiency, so far, detailed for single junction planar thin-film hydrogenated amorphous silicon solar cell is 10.2% , . ScienceDirect ® is a registered trademark of Elsevier B.V. ScienceDirect ® is a registered trademark of Elsevier B.V. Additionally, using small MNPs at the top (P+) layer should allow a significant portion of the optical energy to propagate through (it acts like a transparent layer for long wavelengths), meanwhile larger MNPs are placed at the bottom to enhance reflection/scattering. By continuing you agree to the use of cookies. Materials Research Society Symposium Proceedings 1101: KK13‐KK, Novel approaches of light management in thin‐film silicon solar cells, Plasmonic silicon solar cells: impact of material quality and geometry, Island size effects in nanoparticle‐enhanced photodetectors, Cascaded plasmonic metamaterials for phase‐controlled enhancement of nonlinear absorption and refraction, A‐Si:H Solar Cells with embedded silver Nanoparticles, 1. However, the recent developments in thin film solar cell technology with increase in efficiency, yield and durability all point towards a promising future for this technology. Hence, if small size MNPs with diameters in the range of 18 nm (i.e., resonating at these high frequencies) are used in the top P+ layer, they would enhance the scattering and absorption of this spectrum. Numerical analysis of aluminum nanoparticle influence on the characteristics of a thin-film solar cell. For this reason the degree of freedoms to optimize the model are limited by the type and dimension of the original sample has already defined (in case of no MNPs). [ 3 In our previous publication 17, we showed that how EQEs can be changed by placing the MNPs at different positions within the layer of the absorber. With amorphous cells, it’s a maximum of 9-10% efficiency. This would require: first, optimizing the thickness of the highly doped layer; and second, optimizing the level of dopant. 3). © 2017 The Authors. 17. MNPs (few nanometers in diameter) can scatter a wide range of visible light, and also can create high intensity near‐fields in their vicinity 10. A view of the structure is shown in Figure 2A. This is known as the Staebler-Wronski effect. Remarkable manufacturing cost reduction in solar cells can be achieved using thin film hydrogenate amorphous silicon (A‐Si:H) instead of bulk silicon. However, a pronounced efficiency drop could be incurred by utilizing thin film silicon 1. Meanwhile, use of such small MNPs would still allow the relatively low‐frequency spectrum to travel through the top layers and reach the bottom ones. Use the link below to share a full-text version of this article with your friends and colleagues. The recent trend in the a-Si,Ge:H Sanyo has developed a hybrid solar cell by applying coatings of amorphous silicon onto a mono-crystalline solar cell (see accompanying diagram). It is believed that embedding metallic nanoparticles (MNPs) inside the structure could increase light scattering. Final Technical Report . a solar cell based on amorphous silicon with a solar conversion efficiency of about 2.4% (for historical discussion see Reference [6, 7]). However, they are more flexible … University of Toledo . Send article to Kindle To send this article to your Kindle, first ensure is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Typically, any thin film solar cells suffer from a huge reduction in light absorption within absorber layers (semiconductors), and that can cause efficiency drop due to inherent surface reflection. In search of ways to improve efficiency, we have investigated the impact of MNP's size, and location within the solar cell, in addition to the effect of defects, and doping levels on the overall efficiency. Low energy light in the range 600-750 nm is converted to 550-600 nm light due to the incoherent photochemical process. Semiconductor physics, quantum electronics and optoelectronics. Researchers have developed an integrated PVT using amorphous silicon that optimizes the efficiency of both solar electricity generation and solar heat generation in one convenient package. Front transparent contact layer is also investigated by using SnO2:F and ZnO:Al to achieve an efficient photon absorption in the active layer. Improved Efficiency in Hydrogenated Amorphous Silicon Solar Cells Irradiated by Excimer Laser A. This work was supported by the grant from the National Science Foundation of USA (Grant No. Number of times cited according to CrossRef: Cluster-assembled devices for solar energy conversion. Efficiency improvement of a-Si:H Thin-Film Solar Cells by phosphorus doping of absorption layer with a-Si:H buffer layer at p/i interface. Learn about our remote access options, Department of Electrical Engineering and Computer Science, University of Tennessee, Knoxville, Tennessee, Ahmadreza Ghahremandi, Department of Electrical Engineering and Computer Science, University of Tennessee, Knoxville, TN. We also calculated the amount of efficiency, FF, Voc, and Jsc for various scenarios. The results of simulations were compared to relevant measured data, and it showed a good agreement. We report an increase in light harvesting efficiency of a hydrogenated amorphous silicon (a-Si: H) thin-film solar cell due to a rear upconvertor based on sensitized triplet-triplet-annihilation in organic molecules. Also, hydrogenated amorphous silicon, a-Si:H in short, is of technical significance for thin-film solar cells. Comparison of amorphous silicon absorber materials: Light-induced degradation and solar cell efficiency M. Stuckelberger,a) M. Despeisse, G. Bugnon, J.-W. Schuttauf, F.-J. Typically, the amount of surface roughness is related to transparent conductive oxide (TCO) type. Random embedding of MNPs has resulted in a drop of solar cell efficiency. The optical simulations permit investigating optical losses at the individual layers. Simulation result shown in Figure 4B, is validating our observation, and indicates pronounced efficiency improvement when placing MNPs only inside the top P+ layer as expected. Polycrystalline panel efficiency ratings will typically range from 15% to 17%. Only a slight discrepancy is seen – thus validating our models. The efficiency of a-Si:H degrades over time under exposure to light. Crystalline cells can absorb and use anywhere from 14 – 20% of the incoming photon rays from the sun. Figure 6 shows that the extinction coefficient of amorphous silicon which has exponential growth rate in UV region. The surface roughness would impact on the overall performance. To demonstrate this effect, a P‐I‐N structure was analyzed before and after embedding the MNPs 17, and a huge difference between the results with and without accounting for the presence of the defects was seen in our first experiment (efficiency of 9.8% without considering defects, and 3.5% with as seen in Fig. This extra optical loss is due to a large Shockley Read Hall recombination rate – which would mean a huge efficiency drop. However, light can face optical losses for small (few nanometer) MNPs that can supersede scattering. Amorphous cells offer higher efficiency than the other two. It changes between 10 nm to 100 nm. The accuracy of the results is directly related to the input data. Carlson and Wronski’s report of the current density versus output voltage is pre- sented in Figure 12.1 (along with the curve from a far more efficient cell reported in Enter your email address below and we will send you your username, If the address matches an existing account you will receive an email with instructions to retrieve your username. 11. The cell was studied for open-circuit voltage, external quantum efficiency, and short-circuit current density, which are building blocks for solar cell conversion efficiency. This improvement is typically done using various light trapping techniques such as utilizing textured back reflectors for pronounced light scattering within the cell thus achieving higher absorption. The efficiency of amorphous silicon solar cells has a theoretical limit of about 15% and realized efficiencies are now up around 6 or 7%. All through the exploration, the designed amorphous solar cell includes three original parts. Extensive simulation, based on our 3D combined optical‐electric modeling toolbox has led to very promising results for ways to achieve higher efficiency. 3A), and our simulation results (Fig. First, a significant efficiency drop detected after adding the MNPs (related to the substantial number of defects left). Therefore methods need to be developed to enhance scattering and to improve absorption if possible. and you may need to create a new Wiley Online Library account. Topological characterization of antireflective and hydrophobic rough surfaces: are random process theory and fractal modeling applicable? The scientists claim the performance marks an increase of around 16% on currently realized efficiencies for amorphous silicon solar. At the present time some researchers have achieved efficiencies of over 10% for pin junction solar cells based on amorphous silicon while ECD claim an efficiency of 13% for their tandem fluorinated cells. Such as strategically locating small MNPs at the highly doped regions (i.e., P+ and N+) rather than inside the intrinsic layer. The enhancement in both short-circuit current density and open-circuit voltage prompts accomplishing more prominent power conversion efficiency. Mailing Address: 1520 Middle Drive Knoxville, TN 37996‐2250. To understand the effect of existing silver nanoparticles, we studied solar cell's performance after embedding these MNPs at different layers, one layer at a time. So these issues associated with the design and fabrication, need to be resolved to enhance efficiency. This is obviously translated to an energy loss 18-21. Here, various dimensions were examined, and the width, height, and period of the ribbon nanoparticle were taken into account. To achieve higher efficiency, some boosting techniques have been developed for better light absorption. Requires much less silicon. This would simply mean an overall efficiency of 13%. Conclusion will be given in section V. Finally a methodology for a robust simulation will be presented in the Appendix. For instance, using TCO film with large grains would increase the surface roughness 24-26. This crystal structure makes the efficiency rate of polycrystalline panels lower than monocrystalline panels. Table 1 shows the list of parameters that are used for initialization of the 3D model. However, to have appreciable absorption for the spectrum at low frequencies large MNPs (size around 200 nm in diameter) resonate and enhance absorption. Hydrogenated amorphous silicon (a-Si:H) has been effectively utilized as photoactive and doped layers for quite a while in thin-film solar applications but its energy conversion efficiency is limited due to thinner absorbing layer and light degradation issue. It turns out pronounced light absorption happens with very low EQE. Copyright © 2021 Elsevier B.V. or its licensors or contributors. Enhanced thermal stability of silica‐coated gold nanorods for photoacoustic imaging and image‐guided therapy, Chemical synthesis of novel plasmonic nanoparticles, Shape effects in plasmon resonance of individual colloidal silver nanoparticles, A plasmon ruler based on nanoscale photothermal effect, A general design rule to manipulate photocarrier transport path in solar cells and its realization by the plasmonic‐electrical effect, A three‐dimensional multiphysics modeling of thin‐film amorphous silicon solar cells, Semiconductor physics and devices: basic principles, Statistics of the recombinations of electrons and holes, Morphological and optical characterization of SnO2:F thin films deposited by spray pyrolysis, Evolution of microstructure and related optical properties of ZnO grown by atomic layer deposition, Role of film thickness on the properties of ZnO thin films grown by sol‐gel method, 3‐D optical modeling of thin‐film silicon solar cells on diffraction gratings, Theoretical analysis of trapping and recombination of photo generated carriers in amorphous silicon solar cells, Numerical simulation of photocurrent in a solar cell based amorphous silicon, Semiconductor optoelectronic devices introduction to physics and simulation, A discretization method for the solution of Maxwell's equations for six‐component fields, Rigorous coupled‐wave analysis of planar‐grating diffraction, Determination of the optical parameters of a‐Si:H thin films deposited by hot wire–chemical vapor deposition technique using transmission spectrum only, Strategies for designing high efficient thin‐film amorphous silicon solar cells. DE-AC36-99-GO10337 High Efficiency and High Rate Deposited Amorphous Silicon-Based Solar Cells . Besides, the front transparent contact layer was also inquired by using SnO2:F and ZnO:Al materials to improve the photon absorption in the photoactive layer. However, if UV rays instead of being absorbed mostly in P+ layer (close to the surface) reach to the depleted region, and propagate in a longer path inside the P‐I‐N device, then more electron–hole pairs will be generated and will be separated (having more separated charges can be expected as more electricity). They call this a … Subcontract Report For instance using the accurate solar spectrum of energy as an excitation for electromagnetic propagation, applying the right values for electro‐optical material properties to solve light intensity inside the structure, and also initializing semiconductor with right amount of carrier density inside P‐I‐N, and recombination rate to solve continuity equation (in physics device) are some basic steps to start modeling for solar cells. Alternatively, MNPs are intentionally placed within solar cells. One of the disadvantages of embedding MNPs inside a semiconductor is increasing the density of defects especially around the MNPs. 3B) rather huge drop in conversion efficiency which is once more consistent with Ref. Lack of any control on mesh generation can cause long time of processing, or out of memory due to aggressive computations. Learn more. However, embedding MNPs can also cause significant structure defects and pronounced efficiency drop as well – it has been indicated by many experiments that disproved this belief. Along these lines, we carried out a detailed 3D multiphysics modeling of plasmon solar cells 17, and we studied the effect of MNPs on performance in search for efficiency enhancement. To avoid such a problem, MNPs should be placed in a proper location so they would cause minimal impact on efficiency reduction. We review the progress made by amorphous silicon solar cells, including the emerging technology of solar cells of microcrystalline silicon. Although surprisingly, the efficiency has dropped to 3.5% in contradiction to the common belief that it should be enhanced upon using MNPs – (however, if no defects exist, the efficiency though would be 9.77% as indicated in Fig. This can lead to significant cost differences to cover your energy needs. 2B). The agreement seen in Figure 3B between simulation and measurement is good, and it validates our model again. Cluster Beam Deposition of Functional Nanomaterials and Devices. The maximum size of element depends on: 1‐the longest side of each single layer 2‐operation wavelength. Optical paths inside solar cells for different type of electrodes. A modeling toolbox was successfully developed for 3D solar cells performance analysis 17, and it was validated by previously published experimental data carried out by Ref. Download : Download high-res image (174KB)Download : Download full-size image. Hence, the thickness of P+ layer should be thinned and the level of dopant (here P+) needs to be decreased enough, thus pushing the depleted region closer to the surface of the semiconductor on the top. … 2020 IEEE International Conference on Semiconductor Electronics (ICSE). Subsequently, models were used to predict performance, and over 30% improvement in solar cell efficiency (~13% is predicted); which is beyond the state of the art. A periodic structure of a trapezoidal shape (like that of 27) is designed and implemented to the 3D model of 11. Toledo, Ohio . Enhancing light absorption within thin film amorphous silicon (a-Si) solar cells should lead to higher efficiency. This improvement is typically done using various light trapping techniques such as utilizing textured back reflectors for pronounced light scattering within the cell thus achieving higher absorption. If you do not receive an email within 10 minutes, your email address may not be registered, According to … In this paper, new design rules for embedding MNPs inside thin film amorphous silicon solar cells will be presented that would lead to solar cell efficiency enhancement. In our model, silver nanoparticles are designed as spheres with 18 nm diameter and placed in a random 2D array with a maximum center‐to‐center spacing of 36 nm. So increasing the thickness of intrinsic layer of the semiconductor is not suggested for efficiency improvement at UV range, unless the absorber has low light absorption at this frequency range. Figure 7 shows the geometry of the whole structure in 3D with considering boundary conditions as well. To overcome such confinements, it is expected to adjust better comprehension of device structure, material properties, and qualities since a little enhancement in the photocurrent significantly impacts on the conversion efficiency. Also the chance of existing MNPs at the right place (for resonance) is low. X. Deng . At high frequencies (UV region), most of the impinging solar energy on the cell is absorbed at the top of the semiconductor close to the surface (here P+ region), and it happens before approaching UV rays to the junction or depleted region. Random textured or corrugated external/internal interfaces are used to improve scattering 2-8, while transparent conductive oxide (TCO) layers are utilized to minimize reflections at interfaces, additionally highly reflective surfaces are used to enhance back reflections. For instance, to consider the effect of defects around MNPs (inside the intrinsic region), the recombination rate was considered 100 times higher than normal value estimated when inside intrinsic region. On the basis of our 3D multiphysics (optical‐electric) modeling, we developed a design guideline for embedding these MNPs and reducing the impact of defects created in the embedding process. The maximum efficiency of thin‐film amorphous silicon solar cells is estimated to be ∼14–15%. However, the efficiency of an a-Si cell suffers a significant drop of about 10 to 30 percent during the first six months of operation. Augmentation of power conversion efficiency of amorphous silicon solar cell employing poly(methyl methacrylate-co-acrylic acid) nanospheres encapsulated with gold nanoparticles. At this point, the intensity of light for the ultraviolet (UV) rays (high frequencies) close to the N‐type region (at the back) is very weak, since most of their energies have already been absorbed by the top layers of the absorber (i.e., inside the P+, and intrinsic region), and mostly Infrared (IR) rays exist. A 3D model of a thin film amorphous silicon solar cell has been developed which accounts for surface roughness as well. The full text of this article hosted at is unavailable due to technical difficulties. The best power conversion efficiency to date is 2.4% in AM‐1 sunlight. Initialization of the input data is the crucial part of this work. In our investigation, to model the solar cell and to take the effect of surface roughness into account, a 3D device model like a trapezoidal grating is assumed 17. The efficiency of amorphous silicon solar cells that are manufactured in high-volume processes ranges from 6% to 9%. Enhancing light absorption within thin film amorphous silicon (a‐Si) solar cells should lead to higher efficiency. Blue Light-Emitting Si Quantum Dots with Mesoporous and Amorphous Features: Origin of Photoluminescence and Potential Applications, Density Of State Conduction band, a‐Si –Ref, Difference between Defect level and intrinsic level N+,P+‐Ref, Difference between Defect level and intrinsic level intrinsic‐Ref, Refractive index of materials (attached to the top and the bottom of the absorber). Large MNPs should be placed at the bottom layer (i.e., inside TCO – next to the N+ region, see Fig. Finally simulation results indicate an impressive efficiency enhancement of up to ~30% which amounts to 13% overall efficiency. Conclusion