DESIGN AND SIMULATION OF INDIUM GALLIUM NITRIDE MULTIJUNCTION TANDEM SOLAR CELLS

Nargis Akter

Abstract: As our global energy expenditure increases exponentially, it is apparent that renewable energy solution must be utilized. Solar PV technology is the best way to utilize the unlimited solar energy. The InGaN is a recently developed novel solar cell material for its promising tunable band gap of 0.7 eV to 3.4 eV for the realization of high efficiency tandem solar cells in space and terrestrial applications. In this work, various numerical simulations were performed using Analysis of Microelectronic and Photonic Structure (AMPS) simulator to explore the possibility of higher efficiency of InGaN based solar cells. At these aim three different types of InGaN based solar cells (single junction, double junction and triple junction) were designed and optimized. Numerical simulations were done with different band gap of InGaN material and found that maximum efficiency occurs around 1.2 eV to 1.5 eV, it has been optimized at 1.34 eV for (single junction solar cell) with maximum conversion efficiency of 25.02%. The single junction solar cell were simulated and optimized for optimum thickness of p-layer and n-layer. Doping concentration and back contact material of the designed cells were investigated and found that 1×10 16 cm -3 of doping concentration for both p and n type material and Nical as back contact with FbL of 1.3 eV are best fitted for higher conversion efficiency. From tunable band gap of InxGa1-xN material, selection has been done at 1.61 eV, 1.44 eV and 1.21 eV for the top, middle and bottom cells respectively for the tandem triple junction and double junction (1.61 eV, 1.21 eV) solar cells. The best conversion efficiency of the single junction, double junction and triple junction solar cells are 25.019%, 35.45% and 42.34% respectively. Effect of tunnel junction for the tandem cells also investigated and found that required thickness for tunnel junction is around 25 nm with doping concentration, NA and ND of 1×1019 and 1×1016 respectively were found in this analysis. Finally, the temperature coefficient (TC) of the above proposed cells were simulated to investigate the thermal stability of the proposed cells. It has been found that the TC of InGaN cells is about -0.04%/°C, which indicate the higher stability of the proposed cells

Keywords: Solar electricity, Solar cells, InGaN, Tandem, Ultra thin film, AMPS, Conversion Efficiency, Thermal stability.

DOI: https://doi.org/10.15623/ijret.2014.0301056