Photonic crystal microcrystalline silicon solar cells
TL;DR: In this paper, a method to incorporate photonic crystal structures into thin-film microcrystalline silicon photovoltaic layers while suppressing undesired defects formed in the microcrystaline silicon was proposed.
Abstract: Enhancing the absorption of thin-film microcrystalline silicon solar cells over a broadband range in order to improve the energy conversion efficiency is a very important challenge in the development of low cost and stable solar energy harvesting. Here, we demonstrate that a broadband enhancement of the absorption can be achieved by creating a large number of resonant modes associated with two-dimensional photonic crystal band edges. We utilize higher-order optical modes perpendicular to the silicon layer, as well as the band-folding effect by employing photonic crystal superlattice structures. We establish a method to incorporate photonic crystal structures into thin-film (~500 nm) microcrystalline silicon photovoltaic layers while suppressing undesired defects formed in the microcrystalline silicon. The fabricated solar cells exhibit 1.3 times increase of a short circuit current density (from 15.0 mA/cm2 to 19.6 mA/cm2) by introducing the photonic crystal structure, and consequently the conversion efficiency increases from 5.6% to 6.8%. Moreover, we theoretically analyze the absorption characteristics in the fabricated cell structure, and reveal that the energy conversion efficiency can be increased beyond 9.5% in a structure less than 1/400 as thick as conventional crystalline silicon solar cells with an efficiency of 24%. © 2015 The Authors. Progress in Photovoltaics: Research and Applications published by John Wiley & Sons Ltd.
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01 Jan 2019
TL;DR: The photovoltaic conversion of solar energy starts to give an appreciable contribution to power generation in many countries, with more than 90% of the global PV market relying on solar cells base.
Abstract: Photovoltaic (PV) conversion of solar energy starts to give an appreciable contribution to power generation in many countries, with more than 90% of the global PV market relying on solar cells base...
260 citations
TL;DR: The role of plasmonic nanoshells, embedded within a ultrathin microcrystalline silicon solar cell, in enhancing broadband light trapping capability of the cell and, at the same time, to reduce the parasitic loss is investigated.
Abstract: With the objective to conceive a plasmonic solar cell with enhanced photocurrent, we investigate the role of plasmonic nanoshells, embedded within a ultrathin microcrystalline silicon solar cell, in enhancing broadband light trapping capability of the cell and, at the same time, to reduce the parasitic loss. The thickness of the considered microcrystalline silicon (μc-Si) layer is only ~1/6 of conventional μc-Si based solar cells while the plasmonic nanoshells are formed by a combination of silica and gold, respectively core and shell. We analyze the cell optical response by varying both the geometrical and optical parameters of the overall device. In particular, the nanoshells core radius and metal thickness, the periodicity, the incident angle of the solar radiation and its wavelength are varied in the widest meaningful ranges. We further explain the reason for the absorption enhancement by calculating the electric field distribution associated to resonances of the device. We argue that both Fabry-Perot-like and localized plasmon modes play an important role in this regard.
43 citations
TL;DR: In this paper, a silicon thin-film solar cell (TFSC) integrated with the silver nanoparticles is presented, which consists of anti-reflection, absorption and reflective layers in which the anti-reflective layer is made of pyramids of TiO2.
36 citations
TL;DR: This work investigates the improvement of the conversion efficiency of ultra-thin microcrystalline silicon (μc-Si) solar cells incorporating photonic-crystal structures, where light absorption is strongly enhanced by the multiple resonant modes in the photonic crystal.
Abstract: We investigate the improvement of the conversion efficiency of ultra-thin (~500nm-thick) microcrystalline silicon (μc-Si) solar cells incorporating photonic-crystal structures, where light absorption is strongly enhanced by the multiple resonant modes in the photonic crystal. We focus on the quality of the intrinsic μc-Si layer deposited on the substrate, which is structured to form a photonic crystal at its upper surface with a period of several hundred nanometers. We first study the crystalline quality from the viewpoint of the crystalline fraction and show that the efficiency can be improved when the deposition conditions for the μc-Si layer are tuned to give an almost constant crystalline fraction of ~50% across the entire film. We then study the influence of the photonic-crystal structure on the crystalline quality. From transmission-electron microscope images, we show that the collision of μc-Si grains growing at different angles occurs when a photonic-crystal structure with an angular surface is used; this can be suppressed by introducing a rounded surface structure. As a result, we demonstrate an efficiency of 8.7% in a ~500-nm thick, homo-junction μc-Si solar cell, which has only ~1/4 the thickness of typical μc-Si solar cells. We also discuss the possibility of further improving the efficiency by performing calculations that focus on the absorption characteristics of the fabricated cell structure.
22 citations
TL;DR: The multiple plasmon resonances, together with the antireflection functionality arising from the conformally deposited top surface of the 3D solar cell, lead to a 22% and an 11% improvement in power conversion efficiency of the nc-Si:H thin-film solar cells compared to flat cells and cells employing nanoparticle clusters, respectively.
Abstract: We report three-dimensionally assembled nanoparticle structures inducing multiple plasmon resonances for broadband light harvesting in nanocrystalline silicon (nc-Si:H) thin-film solar cells. A three-dimensional multiscale (3DM) assembly of nanoparticles generated using a multi-pin spark discharge method has been accomplished over a large area under atmospheric conditions via ion-assisted aerosol lithography. The multiscale features of the sophisticated 3DM structures exhibit surface plasmon resonances at multiple frequencies, which increase light scattering and absorption efficiency over a wide spectral range from 350–1100 nm. The multiple plasmon resonances, together with the antireflection functionality arising from the conformally deposited top surface of the 3D solar cell, lead to a 22% and an 11% improvement in power conversion efficiency of the nc-Si:H thin-film solar cells compared to flat cells and cells employing nanoparticle clusters, respectively. Finite-difference time-domain simulations were also carried out to confirm that the improved device performance mainly originates from the multiple plasmon resonances generated from three-dimensionally assembled nanoparticle structures.
22 citations
References
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TL;DR: This work numerically investigates the light trapping effect in the weak absorption regime for 1.5 μm thick crystalline silicon at normal incidence and develops a simulation method combining finite-difference time-domain (FDTD) calculations and the optimization algorithm (Nlopt-COBYLA).
Abstract: We numerically investigate the light-absorption behavior of thin-film silicon for normal-incident light, using surface textures to enhance absorption. We consider a variety of texture designs, such as simple periodic gratings and commercial random textures, and examine arbitrary irregular periodic textures designed by multi-parameter optimization. Deep and high-index-contrast textures exhibit strong anisotropic scattering that is outside the regime of validity of the Lambertian models commonly used to describe texture-induced absorption enhancement for normal incidence. Over a 900-1100 nm wavelength range, our optimized surface texture in two dimensions (2D) enhances absorption by a factor of 2.7 πn, considerably larger than the original πn Lambertian result and exceeding by almost 50% a recent generalization of Lambertian model for periodic structures in finite spectral range. However, the πn Lambertian limit still applies for isotropic incident light, and our structure obeys this limit when averaged over all the angles. Therefore, our design can be thought of optimizing the angle/enhancement tradeoff for periodic textures.
114 citations
"Photonic crystal microcrystalline s..." refers background in this paper
...To overcome this issue, a randomly textured structure [8,9] is widely used, where photons are trapped by scattering effects....
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TL;DR: In this paper, a general framework for the design of thin-film photovoltaics based on a partially disordered photonic crystal that has both enhanced absorption for light trapping and reduced sensitivity to the angle and polarization of incident radiation is presented.
Abstract: We present a general framework for the design of thin-film photovoltaics based on a partially disordered photonic crystal that has both enhanced absorption for light trapping and reduced sensitivity to the angle and polarization of incident radiation. The absorption characteristics of different lattice structures are investigated as an initial periodic structure is gradually perturbed. We find that an optimal amount of disorder controllably introduced into a multi-lattice photonic crystal causes the characteristic narrow-band, resonant peaks to be broadened resulting in a device with enhanced and robust performance ideal for typical operating conditions of photovoltaic applications.
109 citations
TL;DR: In this paper, a new world record efficiency was achieved for single-junction microcrystalline silicon solar cells, with a conversion efficiency of 10.69%, independently confirmed at ISE CalLab PV Cells.
Abstract: This short communication highlights our latest results towards high-efficiency microcrystalline silicon single-junction solar cells. By combining adequate cell design with high-quality material, a new world record efficiency was achieved for single-junction microcrystalline silicon solar cell, with a conversion efficiency of 10.69%, independently confirmed at ISE CalLab PV Cells. Such significant conversion efficiency could be achieved with only 1.8 µm of Si.
99 citations
TL;DR: In this article, a new high-pressure depletion deposition method is described that suppresses ion bombardment and yields low defect densities. And the influence of the microcrystalline texture formed spontaneously during growth on optimizing optical confinement has been studied.
87 citations
TL;DR: In this paper, the performance of pin and nip solar cells with microcrystalline silicon (μc-Si:H) absorber layers of different thickness was investigated.
75 citations