FIRST-PRINCIPLES STUDY ON SI24 AND 2D MATERIAL HETEROSTRUCTURES FOR SOLAR CELL APPLICATIONS

Abstract

Through first-principles calculations, we investigated a new silicon allotrope (Si24) and 2D material heterostructures for solar cell applications. Our results show that Si24 is energetically, dynamically, and thermally stable (under 500 K). Its intrinsic defects have negligible impacts on the overall properties. Group III and V elements can be doped into Si24 with low formation and ionization energies and delocalized carriers, meaning it is easy to realize p- and n-type Si24, respectively, and Si24 is promising for solar cell applications. 2D materials can be vertically stacked, forming a heterostructure acting as excitonic solar cell. To find the heterostructures with high power conversion efficiency (PCE), high-throughput computational screening was performed to study the band alignments of 1,540 heterostructures formed by 56 2D semiconducting/insulating materials. As a result, 91 heterostructures with estimated PCE higher than 15% have been identified, of which 17 heterostructures are predicted to have PCE higher than 20%.