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Numerical simulation of solar radiation transmittance for textured surface silicon photovoltaic cells
Authors
	Khafizov R.Z.
	Timofeev A.E.
Date of publication
	2016
Abstract
	To achieve high solar energy conversion efficiency design and technological parameters of the solar cells must satisfy many requirements. One of the main requirements is a high transmittance of sunlight by the surface of the cell. Thin dielectric antireflection coatings (ARC) [1] and structuring of the silicon surface in the form of inverted pyramids are used [2] for this purpose. To predict the optimal parameters of such combined structures numerical modeling can be effectively applied [3]. This paper presents the simulation results of the spectral dependence of solar radiation transmittance through the textured surface of silicon with single (SiO2) and double layer (SiO2 + Si3N4) dielectric antireflection coating. For modeling the Synopsys TCAD software package was used. The simulation results of the spectral dependence of solar radiation transmittance by the solar cell with pyramidal textured surface and single (SiO2) and double (SiO2 + Si3N4) layer antireflection coating (ARC) are presented in this work. The most preferred two-layer antireflection coating is the SiO2 + Si3N4 structure, where silicon oxide is used as a thin (~ 30 nm) sublayer, providing a low density of recombination centers on the silicon solar cell surface, and Si3N4 is the most suitable materials, which reduces reflection of solar radiation by the surface of the silicon. It is also important that these materials are standard in microelectronic manufacturing. The simulation illustrates opportunities to increase in energy conversion efficiency of solar cells. Transmittance of solar radiation increases with increasing step distance of the pyramids up to values of 40 microns. The efficiency loss caused by reflection of sunlight in pyramidal textured substrates with double-layer antireflection dielectric coating can be reduced to 2-3%. The maximum energy transfer for such a structure is achieved when the total thickness of the coating is 50 µm. The use of single layer coatings (SiO2) gives slightly worse results, but of the more simple technology such variant is also worthy of attention. It was shown that the formation of structure in the form of an inverted pyramids with a corresponding geometric parameters of antireflection coatings provides a significant (up to 30% in the shortwave region of the solar spectrum) improving the use of solar energy. It should be noted that achieving high absorption of sunlight is only one part of creating high-efficiency solar cells. This problem must be solved taking into account other factors influencing the quality of solar cells, such as losses due to the recombination of photogenerated carriers in the bulk and on the surface [4] and resistivity losses in contact grids. In particular, an important point that should be taken into account is that the pyramidal textured surface is characterized by increased rate of surface recombination due to the change in surface orientation from (100) to (111) and increasing the area by about 70% [5]. The work is done in Nation Research University of Electronic Technology (Russia, Moscow) with financial support of the Ministry of education and science of the Russian Federation – the unique identifier of the applied scientific researches is RFMEFI57814X00012.
Keywords
	solar cell, antireflection coating (ARC), texture, transmittance, efficiency, optimization.
Library reference
	Khafizov R.Z., Timofeev A.E. Numerical simulation of solar radiation transmittance for textured surface silicon photovoltaic cells // Problems of Perspective Micro- and Nanoelectronic Systems Development - 2016. Proceedings / edited by A. Stempkovsky, Moscow, IPPM RAS, 2016. Part 4. P. 95-99.
URL of paper
	http://www.mes-conference.ru/data/year2016/pdf/D019.pdf