Theoretical simulations of the effects of the indium content, thickness, and defect density of the i-layer on the performance of p-i-n InGaN single homojunction solar cells

In this study, we conducted numerical simulations with the consideration of microelectronic and photonic structures to determine the feasibility of and to design the device structure for the optimized performance of InGaN p-i-n single homojunction solar cells. Operation mechanisms of InGaN p-i-n single homojunction solar cells were explored through the calculation of the characteristic parameters such as the absorption, collection efficiency (χ), open circuit voltage (Voc), short circuit current density (Jsc), and fill factor (FF). Simulation results show that the characteristic parameters of InGaN solar cells strongly depend on the indium content, thickness, and defect density of the i-layer. As the indium content in the cell increases, Jsc and absorption increase while χ, Voc, and FF decrease. The combined effects of the absorption, χ, Voc, Jsc, and FF lead to a higher conversion efficiency in the high-indium-content solar cell. A high-quality In0.75Ga0.25N solar cell with a 4 μm i-layer thickness can exhibit as high a conversion efficiency as ∼23%. In addition, the similar trend of conversion efficiency to that of Jsc shows that Jsc is a dominant factor to determine the performance of p-i-n InGaN solar cells. Furthermore, compared with the previous simulation results without the consideration of defect density, the lower calculated conversion efficiency verifies that the sample quality has a great effect on the performance of a solar cell and a high-quality InGaN alloy is necessary for the device fabrication. Simulation results help us to better understand the electro-optical characteristics of InGaN solar cells and can be utilized for efficiency enhancement through optimization of the device structure.In this study, we conducted numerical simulations with the consideration of microelectronic and photonic structures to determine the feasibility of and to design the device structure for the optimized performance of InGaN p-i-n single homojunction solar cells. Operation mechanisms of InGaN p-i-n single homojunction solar cells were explored through the calculation of the characteristic parameters such as the absorption, collection efficiency (χ), open circuit voltage (Voc), short circuit current density (Jsc), and fill factor (FF). Simulation results show that the characteristic parameters of InGaN solar cells strongly depend on the indium content, thickness, and defect density of the i-layer. As the indium content in the cell increases, Jsc and absorption increase while χ, Voc, and FF decrease. The combined effects of the absorption, χ, Voc, Jsc, and FF lead to a higher conversion efficiency in the high-indium-content solar cell. A high-quality In0.75Ga0.25N solar cell with a 4 μm i-layer thickness can e...

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