Light trapping in p-i-n superlattice based InGaN/GaN solar cells using photonic crystal

The InGaN material system offers substantial potential in developing ultra-high efficiency solar cell devices due to its unique material properties. The paper proposes a solar cell design having p-i-n superlattice In_xGa_1−xN/GaN based active layer structure supported by photonic crystal (PhC) assembly at the top, with a periodic pattern extending from top anti-reflective coating (ARC) to inside the p-type GaN layer. The paper presents the optical study and optimization of all the required parameters, which helps in investigating the roles of different parts of the structure. The studies are performed at low Indium concentration (up to 20 %) as higher concentration of Indium in GaN is practically not feasible from growth and fabrication point of view. We have also analyzed how the performance varies with the depth of the PhC pattern. Absorption enhancement occurs as the combination of ARC and PhC structures acts as an impedance matching layer, also the incident light is coupled to the quasi guided modes of the PhC structure. Besides, PhC structure acts as a diffraction grating structure allows light to bend inside the active layers, not allowing it to leave the structure through reflection.