DESIGN AND SIMULATION OF INDIUM GALLIUM NITRIDE MULTIJUNCTION TANDEM SOLAR CELLS

Abstract

As our global energy expenditure increases exponent ially, it is apparent that renewable energy solutio n must be utilized. Solar PV technology is the best way to utilize the unlimited solar energy. The InGaN is a recently developed no vel 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 cel ls in space and terrestrial applications. In this work, various numerical simul ations were performed using Analysis of Microelectr onic and Photonic Structure (AMPS) simulator to explore the possibility of high er efficiency of InGaN based solar cells. At these aim three different types of InGaN based solar cells (single junction, double ju nction and triple junction) were designed and optim ized. 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 cel l) with maximum conversion efficiency of 25.02%. Th e single junction solar cell were simulated and optimized for optimum thickness of p-layer and n-layer. Doping concentration and ba ck contact material of the designed cells were investigated and found that 1◊1 0 16 cm -3 of doping concentration for both p and n type material and Nical as back contact with ΦbL of 1.3 eV are best fitted for higher conversion ef ficiency. From tunable band gap of In xGa 1-xN material, selection has been done at 1.61 eV, 1.44 eV and 1.21 eV for the t op, middle and bottom cells respectively for the ta ndem triple junction and double junction (1.61 eV, 1.21 eV) solar cells. The best c onversion 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, N A and N D of 1◊10 19 and 1◊10 16 respectively were found in this analysis. Finally, the temperature co efficient (TC) of the above proposed cells were sim ulated to investigate the thermal stability of the proposed cells. It has been found that the TC of InGaN cells is about -0.04%/°C, whic h indicate the higher stability of the proposed cells.