Synthesis and Characterization of Highly Transparent Sol-Gel Glass for Photovoltaic Applications
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1113-F09-24
Synthesis and Characterization of Highly Transparent Sol-Gel Glass for Photovoltaic Applications Mariyappan Shanmugam, Mahdi Farrokh Baroughi, XingZhong Yan, and David Galipeau
Department of Electrical Engineering and Computer Science, South Dakota State University, SD 57007, USA
ABSTRACT Room temperature sol-gel synthesis and optical characterization of highly transparent silica glass for photovoltaic (PV) applications is presented in this paper. Tetraethyl orthosilicate (TEOS), Ethanol, Hydrochloric acid (HCl) and deionized water were used as precursors in the volumetric ratio of 4:4.3:0.1:3.2 ml. Silica glass of thickness in the range of 0.5-1 cm were obtained with an average transmittance of 93% and absorption coefficient (α) of 0.08 cm-1 in a wide wavelength window of 350-1100 nm. Application of the developed sol-gel silica glass on solar ray concentration, anti-reflective coating (ARC) and effect of surface passivation on silicon wafers were examined. Carrier lifetime of the sol-gel silica passivated silicon substrate was 16µs and the calculated surface recombination velocity of the was 2200 cm/sec. Very low value of α, high transparency in a wide spectral window and effective surface passivation on silicon suggest that sol-gel processed silica glass can be a potential cost effective candidate for different PV applications. INTRODUCTION Solution based processing of optoelectronic materials has attracted a lot of attention because of its flexibility in design and selection of precursors, low processing temperature, high quality materials and cost effectiveness [1]. The sol-gel processed materials have massive applications in the field of photovoltaics because it is low process temperature and low cost. Low process temperature allows for the fine control on the shape, thickness and quality of materials and on chemical composition, as even small quantities of dopants, such as organic dyes and rare earth metals, can be introduced in to the precursors and end up with uniform three dimensional gel network of the final product [2, 3]. Since there is a flexibility to tune the refractive index of sol-gel derived silica glass by appropriate doping, for example ZnSe, CdTe and CdS quantum dots, it can be used to fabricate waveguides, optical gratings, high precision lenses, optical sensors and also bio active glasses [4]. In the photovoltaic research area, sol-gel technique has been extensively used to synthesize metal oxides for dye-sensitized solar cells and has been reported for development of anti-reflective coating [5]. Solution based antireflective coatings and sol-gel based low loss solar concentrators require highly transparent insulating bulk and thin films [6]. This paper presents room temperature synthesize and characterization of highly transparent sol-gel silica glass in the wavelength window of 350-1100 nm for different photovoltaic applications such as ARC, solar ray concentration and silicon wafer surface passivation to control surface recombination velocity.
EXPERIMENTAL Silica glass was
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