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Byun S.-J.,INSIDEOPTICS Co. | Byun S.Y.,INSIDEOPTICS Co. | Lee J.,INSIDEOPTICS Co. | Lee T.S.,Korea Institute of Science and Technology | And 5 more authors.
Journal of the Korean Physical Society | Year: 2012

The demand to reduce Si usage in Si photovoltaic cells in order to improve the cost-effectiveness is ever-increasing in photovoltaic industry. In this study, we propose a new Si photovoltaic cell structure, in which Si grids are formed and reflectors are positioned in between. The optical absorption efficiency of the proposed cell structure was analyzed by making comparisons with simple Si cells with flat and textured surfaces. A quantitative analysis of the optical absorption was made by using a direct absorption calculation algorithm based on the three-dimensional modeling and ray-tracing technique. The proposed grid-type cell structure was shown to be able to yield an improvement in the absorption efficiency per unit Si volume as high as 91% when compared to typical Si cells with pyramidal surface texturing. © 2012 The Korean Physical Society.


Byun S.Y.,Insideoptics Co. | Byun S.Y.,Seoul National University of Science and Technology | Byun S.-J.,Insideoptics Co. | Byun S.-J.,Sogang University | And 8 more authors.
Journal of Nanoscience and Nanotechnology | Year: 2012

Optimizing the design of the surface texture is an essential aspect of Si solar cell technology as it can maximize the light trapping efficiency of the cells. The proper simulation tools can provide efficient means of designing and analyzing the effects of the texture patterns on light confinement in an active medium. In this work, a newly devised algorithm termed Slab-Outline, based on a ray tracing technique, is reported. The details of the intersection searching logic adopted in Slab-Outline algorithm are also discussed. The efficiency of the logic was tested by comparing the computing time between the current algorithm and the Constructive Solid Geometry algorithm, and its superiority in computing speed was proved. The validity of the new algorithm was verified by comparing the simulated reflectance spectra with the measured spectra from a textured Si surface. © 2012 American Scientific Publishers.


Byun S.-J.,Insideoptics Co. | Byun S.-J.,Sogang University | Yong Byun S.,Insideoptics Co. | Lee J.,Insideoptics Co. | And 5 more authors.
Solar Energy Materials and Solar Cells | Year: 2011

Solar cells, especially thin film solar cells, utilize rough surfaces actively in order to improve light trapping efficiency. In this study, we propose a new optical simulation method, which is capable of taking into consideration the realistic surface and interface morphology. The proposed simulation algorithm is based upon a non-sequential ray tracing technique, and direct calculation of the optical absorption energy is performed by separating the light passing through medium into the coherent part and the incoherent part in the course of non-sequential ray tracing throughout the whole region of solar cell structure. It was shown that the new method can give more accurate estimation of the absolute absorption energy in the individual layer when applied for a thin film Si solar cell structure with rough surface of bidirectional scattering distribution function. Furthermore, the proposed algorithm was proved to be very effective in analyzing solar cells with complex geometry like concentrator photovoltaic system, which necessitates the combination of coherent and incoherent calculation. © 2010 Elsevier B.V. All rights reserved.


Byun S.-J.,InsideOptics Co. | Byun S.-J.,Sogang University | Byun S.Y.,InsideOptics Co. | Byun S.Y.,Seoul National University of Science and Technology | And 8 more authors.
Current Applied Physics | Year: 2011

The effects of the size and density of a pyramidal texture, as formed on the surface of Si solar cells to increase the light trapping efficiency, on the optical reflectance and absorptance were examined by comparing simulation results and experimental observations. A ray tracing algorithm capable of the direct calculation of the absorbed energy in active Si was utilized for the simulation. The simulation results showed that the optical reflectance spectra, i.e., the absorptances, of the textured surface with a fixed density of pyramids were not affected by the pyramid pitch, whereas the spectra with varying density of pyramids decreased with an increase in the density of the pyramids. Observations similar to the simulation results were observed from the experimentally textured surfaces, indicating that the density of the pyramid area, i.e., the area of the flat region, is the most crucial factor affecting the optical behavior of a textured Si surface with three-dimensional pyramid patterns. © 2011 Elsevier B.V. All rights reserved.


Byun S.-J.,INSIDEOPTICS Co. | Byun S.Y.,INSIDEOPTICS Co. | Lee J.,INSIDEOPTICS Co. | Kim W.M.,Korea Institute of Science and Technology | Lee T.-S.,Korea Institute of Science and Technology
Optics Express | Year: 2014

A new moiré pattern appearing in the off-state of a display system with a reflecting surface under illumination of an external ambient light source was analyzed. The origin of the new moiré pattern was attributed to the moiré pattern which is formed on the reflecting surface by external light and plays as a new light source with intensity profile. Configuring an optically equivalent system with no reflecting surface layer was proposed in order to overcome the limitation of new simulation program, which was previously proved to be very efficient in computation time but unable to handle a non-sequential system containing a reflecting surface. It was verified that the new simulation algorithm combined with an equivalent configuration could provide an accurate and computation time-efficient analyses even for a system containing non-sequential stacked layer such as a reflecting surface. ©2014 Optical Society of America.


Byun S.-J.,INSIDEOPTICS Co. | Byun S.Y.,INSIDEOPTICS Co. | Lee J.,INSIDEOPTICS Co. | Kim W.M.,Korea Institute of Science and Technology | And 3 more authors.
Optics Express | Year: 2014

A precise and fast computational method for the simulation and analysis of moiré patterns is proposed. This new algorithm is based on convolution with superposition of the intensity profile which is transmitted from the optical layers and the point spread function. The computational time is shown to be much faster than that of the ray-tracing algorithm because the new algorithm does not involve a massive calculation. Also, information on the moiré pitch can be extracted directly from the sampling data of the moiré patterns. © 2014 Optical Society of America.


Lee T.-S.,Korea Institute of Science and Technology | Kim W.M.,Korea Institute of Science and Technology | Byun S.-J.,Insideoptics Co. | Lee J.,Insideoptics Co. | Byun S.Y.,Insideoptics Co.
Digest of Technical Papers - SID International Symposium | Year: 2015

In this paper, we propose a precise and fast computational method for the simulation and analysis of moiré patterns including a complex, large scale of films and a reflecting surface under illumination of an external ambient light source. This algorithm is based on convolution with superposition of the intensity profile which is transmitted from the optical layers and the point spread function. The computation time is shown to be much faster than that of the conventional ray-tracing algorithm. It was also considered of an optically equivalent system with lection surface layer in order to handle a non-sequential system containing a reflecting surface. © 2015 SID.


Byun S.Y.,INSIDEOPTICS Co. | Byun S.Y.,Seoul National University of Science and Technology | Byun S.-J.,INSIDEOPTICS Co. | Lee T.S.,Korea Institute of Science and Technology | And 3 more authors.
Current Applied Physics | Year: 2013

The optical absorption efficiency (OAE) of thin crystalline Si (c-Si) solar cells was examined by using a direct absorption calculation algorithm based on the three-dimensional modeling and ray-tracing technique. The back contact was assumed to be made of ZnO based oxide layers with different optical constants and metallic electrode, and the front surface was assumed to be Lambertian. Simulation results showed that the insertion of non-absorptive oxide layer between c-Si and Al improved OAE, and that the relative amount of enhancement increased with decreasing refractive index, manifesting the reduction in absorption loss in Al electrode due to the increased total internal reflection. In the case of absorptive oxide layer, although increase in OAE was still attainable when compared with the back contact without oxide, the OAE was subdued significantly due to large absorption loss in oxide layer. The optimal oxide layer thickness was around 200 nm for non-absorptive oxide, and that of absorptive oxide decreased with increasing extinction coefficient. In the case of Ag metal contact, the enhancement of OAE due to the use of oxide layer was much less than the case of Al because of inherent high reflectivity and low absorption loss in Ag layer. © 2013 Elsevier B.V. All rights reserved.


Byun S.Y.,Insideoptics Inc | Byun S.-J.,Insideoptics Inc | Sheen D.,Seoul National University of Science and Technology | Lee T.-S.,Korea Institute of Science and Technology
IEEE Journal of Photovoltaics | Year: 2015

We propose an efficient and accurate finite-difference time-domain (FDTD) algorithm to simulate the absorbance of a thin-film solar cell containing nanometer particles or nonflat layers. This algorithm can extract a closed boundary for an arbitrarily shaped object, with the solar cell model being discretized into a set of Yee's cells to construct the FDTD system. Using this information, we can distinguish the closed boundaries of the components (e.g., particles or layers) of the solar cell and accurately calculate the absorbance of each particle or layer. Moreover, using the closed line (in 3-D, surface) integration instead of the area (in 3-D, volume) integration enables faster calculation and requires less memory. © 2011-2012 IEEE.

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