Microstructure Analysis and Properties of Anti-Reflection Thin Films for Spherical Silicon Solar Cells

Masato Kanayama, Takeo Oku, Tsuyoshi Akiyama, Youichi Kanamori, Satoshi Seo, Jun Takami, Yoshimasa Ohnishi, Yoshikazu Ohtani, Mikio Murozono

Clean Venture 21 Co. Ltd., Kyoto, Japan.
Department of Materials Science, The University of Shiga Prefecture, Shiga, Japan.

DOI: 10.4236/epe.2013.52A003                

Abstract

Structure and properties of anti-reflection thin films of spherical silicon solar cells were investigated and discussed. Conversion efficiencies of spherical Si solar cells coated with F-doped SnO₂ anti-reflection films were improved by annealing. Optical absorption and fluorescence of the solar cells increased after annealing. Lattice constants of F-doped SnO₂ anti-reflection layers, which were investigated by X-ray diffraction, decreased after annealing. A mechanism of atomic diffusion of F in SnO₂ was discussed. The present work indicated a guideline for spherical silicon solar cells with higher efficiencies.

Keywords

Solar Cells; Spherical Silicon; Anti-Reflection Film; FTO; SnO2

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	T. Maruyama and H. Minami, “Light Trapping in Spherical Silicon Solar Cell Module,” Solar Energy Materials and Solar Cells, Vol. 79, No. 2, 2003, pp. 113-124. doi:10.1016/S0927-0248(02)00375-6
[2]	Z. Liu, A. Masuda and M. Kondo, “Investigation on the Crystal Growth Process of Spherical Si Single Crystals by Melting,” Journal of Crystal Growth, Vol. 311, No. 16, 2009, pp. 4116-4122. doi:10.1016/j.jcrysgro.2009.06.042
[3]	M. Gharghi and S. Sivoththaman, “Growth and Structural Characterization of Spherical Silicon Crystals Grown from Polysilicon,” Journal of Electronic Materials, Vol. 37, No. 11, 2008, pp. 1657-1664. doi:10.1007/s11664-008-0547-8
[4]	C. Okamoto, T. Minemoto, M. Murozono1, H. Takakura and Y. Hamakawa, “Defect Evaluation of Spherical Silicon Solar Cells Fabricated by Dropping Method,” Japanese Journal of Applied Physics, Vol. 44, No. 11, 2005, pp. 7805-7808. doi:10.1143/JJAP.44.7805
[5]	Z. Liu, T. Nagai, A. Masuda and M. Kondo, “Seeding Method with Silicon Powder for the Formation of Silicon Spheres in the drop Method,” Journal of Applied Physics, Vol. 101, No. 9, 2007, Article ID: 093505. doi:10.1063/1.2718872
[6]	T. Minemoto and H. Takakura, “Fabrication of Spherical Silicon Crystals by Dropping Method and Their Application to Solar Cells,” Japanese Journal of Applied Physics, Vol. 46, No. 7A, 2007, pp. 4016-4020. doi:10.1143/JJAP.46.4016
[7]	M. Gharghi, “Three-Dimensional Modeling and Simulation of p-n Junction Spherical Silicon Solar Cells,” IEEE Transactions on Electron Devices, Vol. 53, No. 6, 2006, pp. 1355-1363. doi:10.1109/TED.2006.873843
[8]	Z. Liu, A. Masuda and M. Kondo, “Investigating Minority-Carrier Lifetime in Small Spherical Si Using Micro wave Photoconductance Decay,” Journal of Applied Physics, Vol. 103, No. 10, 2008, Article ID: 104909. doi:10.1063/1.2936979
[9]	X. S. Hu, Y. J. Zhang and H. W. Wang, “The Effect of Texture Unit Shape on Silicon Surface on the Absorption Properties,” Solar Energy Materials and Solar Cells, Vol. 94, No. 2, 2010, pp. 258-262. doi:10.1016/j.solmat.2009.09.011
[10]	J. Yoo, G. Yu and L. J. Yi, “Large-Area Multicrystalline Silicon Solar Cell Fabrication Using Reactive Ion Etching (RIE),” Solar Energy Materials and Solar Cells, Vol. 95, No. 1, 2011, pp. 2-6. doi:10.1016/j.solmat.2010.03.029
[11]	S. Hayashi, T. Minemoto, H. Takakura and Y. Hamakawa, “Influence of Texture Feature Size on Spherical Silicon Solar Cells,” Rare Metals, Vol. 25, No. 6, 2006, pp. 115-120. doi:10.1016/S1001-0521(07)60056-4
[12]	T. Minemoto, M. Murozono, Y. Yamaguchi, H. Takakura and Y. Hamakawa, “Design Strategy and Development of Spherical Silicon,” Solar Energy Materials & Solar Cells, Vol. 90, No. 18-19, 2006, pp. 3009-3013. doi:10.1016/j.solmat.2006.06.016
[13]	Z. Liu, A. Masuda and T. Nagai, “A Concentrator Module of Spherical Si Solar Cell,” Solar Energy Materials and Solar Cells, Vol. 91, No. 19, 2007, pp. 1805-1810. doi:10.1016/j.solmat.2007.06.008
[14]	T. Minemoto, M. Murozono, Y. Yamaguchi, H. Takakura and Y. Hamakawa, “Design Strategy and Development of Spherical Silicon Solar Cell with Semi-Concentration Reflector System,” Solar Energy Materials and Solar Cells, Vol. 90, No. 18-19, 2006, pp. 3009-3013. doi:10.1016/j.solmat.2006.06.016
[15]	T. Mizuta, T. Ikuta, T. Minemoto, H. Takakura, Y. Hama kawa and T. Numai, “An Optimum Design of Antireflection Coating for Spherical Silicon Solar Cells,” Solar Energy Materials and Solar Cells, Vol. 90, No. 1, 2006, pp. 46-56. doi:10.1016/j.solmat.2005.01.010
[16]	Y. Ono, T. Oku, T. Akiyama, Y. Kanamori, Y. Ohnishi, Y. Ohtani and M. Murozono, “Microstructure Analysis of Spherical Silicon Solar Cells Coated with Anti-Reflection Films,” Journal of Physics: Conference Series, Vol. 352, 2012, Article ID: 012023. doi:10.1088/1742-6596/352/1/012023
[17]	C. K. Huang, H. H. Lin, J. Y. Chen, K. W. Sun and W. L. Chang, “Efficiency Enhancement of the Poly-Silicon Solar Cell Using Self-Assembled Dielectric Nanoparticles,” Solar Energy Materials and Solar Cells, Vol. 95, No. 8, 2011, pp. 2540-2544. doi:10.1016/j.solmat.2011.03.006
[18]	S. Omae, T. Minemoto, M. Murozono, H. Takakura and Y. Hamakawa, “Crystal Evaluation of Spherical Silicon Produced by Dropping Method and Their Solar Cell Performance,” Solar Energy Materials and Solar Cells, Vol. 90, No. 20, 2006, pp. 3614-3623. doi:10.1016/j.solmat.2006.06.056
[19]	Z. Liu, K. Asai, A. Masuda, T. Nagai, Y. Akashi, M. Murozono and M. Kondo, “Improvement of the Production Yield of Spherical Si by Optimization of the Seeding Technique in the Dropping Method,” Japanese Journal of Applied Physics, Vol. 46, 2007, pp. 5695-5700. doi:10.1143/JJAP.46.5695
[20]	W. Liu, C. Jia, C. Jin, L. Yao, W. Cai and X. Li, “Growth Mechanism and Photoluminescence of CdS Nanobelts on Si Substrate,” Journal of Crystal Growth, Vol. 269, No. 2-4, 2004, pp. 304-309. doi:10.1016/j.jcrysgro.2004.05.093
[21]	T. Minemoto, M. Murozono, Y. Yamaguchi, H. Takakura and Y. Hamakawa, “Novel Deposition Method of Anti Reflective Coating for Spherical Silicon Solar Cells,” Solar Energy Materials & Solar Cells, Vol. 90, No. 18-19, 2006, pp. 2995-3000. doi:10.1016/j.solmat.2006.06.005
[22]	T. Minemoto, H. Takakura and Y. Hamakawa, “Chemical Bath Deposition for the Fabrication of Antireflective Coating of Spherical Silicon Solar Cells,” Solar Energy Materials and Solar Cells, Vol. 90, No. 20, 2006, pp. 3576-3582. doi:10.1016/j.solmat.2006.06.046
[23]	E. Elangovan and K. Ramamurthi, “A Study on Low Cost-High Conducting Fluorine and Antimony-Doped Tin Oxide Thin Films,” Applied Surface Science, Vol. 249, No. 1-4, 2005, pp. 183-196. doi:10.1016/j.apsusc.2004.11.074
[24]	T. Nagai, Z. Liu, A. Masuda and M. Kondo, “Characterization of Spherical Si by Photoluminescence Measurement,” Journal of Applied Physics, Vol. 101, No. 10, 2007, Article ID: 103530. doi:10.1063/1.2736944
[25]	S. Omae, T. Minemoto, M. Murozono, H. Takakura and Y. Hamakawa, “Crystal Characterization of Spherical Silicon Solar Cell by X-ray Diffraction,” Japanese Journal of Applied Physics, Vol. 45, No. 5A, 2006, pp. 3933-3937. doi:10.1143/JJAP.45.3933
[26]	G. J. McCarthy and J. M. Welton, “X-Ray Diffraction Data for SnO2. An Illustration of the New Powder Data Evaluation Methods,” Powder Diffraction, Vol. 4, No. 3, 1989, pp. 156-159. doi:10.1017/S0885715600016638
[27]	P. P. Edwards, A. Porch, M. O. Jones, D. V. Morgan and R. M. Perks, “Basic Materials Physics of Transparent Conducting Oxides,” Dalton Transactions, Vol. 19, 2004, pp. 2995-3002. doi:10.1039/b408864f
[28]	T. Minami, “Transparent Conducting Oxide Semiconductors for Transparent Electrodes,” Semiconductor Science and Technology, Vol. 20, No. 4, 2005, pp. S35-S44. doi:10.1088/0268-1242/20/4/004
[29]	C. H. Han, S. D. Han, I. Singh and T. Toupance, “Micro Bead of Nano-Crystalline F-Doped SnO2 as a Sensitive,” Sensors and Actuators B: Chemical, Vol. 109, No. 2, 2005, pp. 264-269. doi:10.1016/j.snb.2004.12.115
[30]	V. Kumar, A. Govind and R. Nagarajan, “Optical and Photocatalytic Properties of Heavily F–-Doped SnO2 Nanocrystals by a Novel Single-Source Precursor Approach,” Inorganic Chemistry, Vol. 50, No. 12, 2011, pp. 5637-5645. doi:10.1021/ic2003436
[31]	B. Zhang, Y. Tian, J. X. Zhang and W. Cai, “The Studies on the Role of Fluorine in SnO2:F Films Prepared by Spray Pyrolysis with SnCl4,” Journal of Optoelectronics and Advanced Materials, Vol. 13, No. 1, 2011, pp. 89-93.