Type-I Graphene/Si Quantum Dot Superlattice for Intermediate Band Applications
نویسندگان
1 Faculty of Electrical and Computer Engineering, University of Tabriz, Tabriz, Iran
2 Department of Electrical Engineering, Shabestar Branch, Islamic Azad University, Shabestar, Iran
3 Department of Electrical Engineering, Tabriz Branch, Islamic Azad University, Tabriz, Iran
doi
10.22059/jser.2022.349258.1257چکیده
The most important loss mechanism in single junction solar cells is the inability to convert photons with energies below the bandgap to electricity. Due to quantum confinement, graphene-based quantum dots (QDs) provide a means to create an intermediate band (IB) in the bandgap of semiconductors to absorb sub-bandgap photons. In this work, we introduce a new type-I core/shell-graphene/Si QD for use in all Si-based intermediate band solar cells (IBSCs). Slater-Koster Tight-Binding method is exploited to compute the ground state and the band structure of the graphene/Si QD. The ground state is obtained 0.6 eV above the valance band (VB), which is suitable for creating IB between the conduction band and VB of Si. A superlattice (SL) of this QD is created and the mini-band formation in SL is investigated by varying the inter-dot spacing between QDs. A mini-band with roughly 0.3 eV bandgap is observed in the well-aligned and closely packed SL. This SL is embedded in the intrinsic region of the conventional Si-based solar cell. The mini-band in SL works as an IB in the solar cell and results in increased photon absorption. As a result, carrier generation rate improves from 1.48943×1028 m-3s-1 to 7.94192×1028 m-3s-1 and short circuit current density increases from 211.465 A/m2 to 364.19 A/m2.
