Enhancement of hydrogenated amorphous silicon solar cells with front-surface hexagonal plasmonic arrays from nanoscale lithography

Abstract

The study first uses numerical simulations of hexagonal triangle and sphere arrays to optimize the performance of hydrogenated amorphous silicon (a-Si:H) photovoltaic devices. The simulations indicated the potential for a sphere array to provide optical enhancement up to 7.4% compared to a standard cell using a nanosphere radius of 250nm and silver film thickness of 50nm. Next a detailed series of a-Si:H cells were fabricated and tested for quantum efficiency (QE) and characteristic and current-voltage (I-V) profiles using a solar simulator. Triangle and sphere array based cells, as well as the uncoated reference cells are analyzed and the results find that the simulation does not precisely predict the observed enhancement, but it forecasts a trend and can be used to guide fabrication. In general, the measured optical enhancement follows the simulated trend: 1) for triangular arrays no enhancement is observed and as the silver thickness increases the more degradation of the cell; 2) for annealed arrays both measured and simulated optical enhancement occur with the thinner silver thickness. Measured efficiency enhancement reached 20.2% and 10.9% for nanosphere diameter D = 500nm, silver thicknesses h = 50nm and 25nm, respectively. These values, which surpass simulation results, indicate that this method is worth additional investigation.

Self-Cleaning Transparent Heat Mirror with a Plasma Polymer Fluorocarbon Thin Film Fabricated by a Continuous Roll-to-Roll Sputtering Process

“…10 Solar spectrum data were obtained in accordance with ASTM G173 for use as standard parameters for the photovoltaic cells. 39,40 For the graphs and formulas used in calculation, refer to the Supporting Information. T vis /T sol is used primarily as a measure of the performance of a THM, and the theoretical maximum is 2.…”

“…Values were calculated for parameters such as the figure of merit (Φ), integrated solar transmittance and reflectance ( T sol and R sol ), integrated visible transmittance (τ vis ), integrated IR reflectance ( R IR ), and integrated visible transmittance and reflectance ( T vis and R vis ), and T vis / T sol values were then calculated . Solar spectrum data were obtained in accordance with ASTM G173 for use as standard parameters for the photovoltaic cells. , For the graphs and formulas used in calculation, refer to the Supporting Information. T vis / T sol is used primarily as a measure of the performance of a THM, and the theoretical maximum is 2.…”

Scalable honeycomb top contact to increase the light absorption and reduce the series resistance of thin film solar cells

“…A thin metallic film with an array of subwavelength holes has been proposed before to improve the efficiency of organic solar cells [26]. However, the honeycomb pattern benefits from scalable and relatively low cost self-assembled nano-beads lithography technique [11,[27][28][29][30][31]. In [32], the authors used nano-beads lithography to make a perforated metallic film which in turn could be used to lower the resistance of the top contact.…”

“…Massoit and associates used one dimensional array of silver strips to form a broadband light trapping mechanism in order to enhance the light absorption of the cell [10]. Zhang et al, found improved a-Si:H PV device performance with an enhanced front-surface hexagonal plasmonic arrays made from nano-scale lithography [11]. These approaches are promising and this study aims to further those efforts by analyzing a new top contact that is able to be manufactured economically at a large scale.…”

Fabricating ordered 2-D nano-structured arrays using nanosphere lithography

“…They are then ready to be used for any application (e.g. as a mask for plasmonic enhancement of photovoltaic devices [26] ).

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