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Journal ArticleDOI

Photonic crystal microcrystalline silicon solar cells

01 Nov 2015-Progress in Photovoltaics (John Wiley & Sons Ltd.)-Vol. 23, Iss: 11, pp 1475-1483

AbstractEnhancing 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.

Topics: Crystalline silicon (68%), Monocrystalline silicon (64%), Solar cell (63%), Hybrid silicon laser (62%), Quantum dot solar cell (62%)

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Citations
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Journal ArticleDOI
01 Jan 2019
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...

131 citations


Journal ArticleDOI
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.

36 citations


Journal ArticleDOI
Abstract: This paper presents a silicon thin-film solar cell (TFSC) integrated with the silver nanoparticles. It consists of anti-reflection, absorption and reflective layers in which the anti-reflective layer is made of pyramids of TiO2. The purpose of this structure is to allow sunlight to enter the cell at any angle with the minimum reflection and absorption in the wavelength range of 300–1100 nm. The absorbing layer is composed of silicon and when sunlight enters this layer, the molecular bonds break down and release many electrons due to its high absorption coefficient. In this layer, silver spherical nanoparticles are placed to increase the absorption of solar energy by the localized surface plasmon resonances, which will increase the efficiency of the TFSC. The last layer of the structure is a reflective surface of aluminum, which aims to reflect the light into the upper layer to enhance its absorption. We will calculate the key performance metrics for a solar cell such as short-circuit current, open-circuit voltage, fill-factor, and photovoltaic efficiency considering the effects of recombination between silicon substrate and other materials. The numerical results based on the finite-difference time-domain method reveal that the proposed structure has much more absorption due to the anti-reflection layer and the presence of silver nanoparticles that leads to light scattering, light localization, and guided mode excitation compared to conventional TFSC. Our simulations based on the finite-element method show the presented TFSC integrated with silver nanoparticles has a fill-factor of 0.82 and an efficiency of 16.18%.

25 citations


Journal ArticleDOI
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.

20 citations


Journal ArticleDOI
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.

20 citations


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866 citations


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