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Heterostructures based on CuInSe2 absorber with AlP buffer have been modeled for the first time by different stacking schemes and interfacial terminations. Mechanical, electronic and topological properties of CuInSe2/AlP heterostructures along [001] direction were investigated using full potential linear augmented plane wave (FP-LAPW) method. Optimal interfacial distance, thermodynamic stability and band alignment have been computed systematically. The magnitudes of core level binding energy differences are in accordance with interfacial adhesion energies. Absolute deformation potentials ADPs of band energies as a function of (001) biaxial strain were determined. With redressing ADPs, the revised valence and conduction band offsets have increased and decreased, respectively. AlP has strong resistance to biaxial strain in the evolution of band energy edges. Topological properties and density of states were used to investigate the relationship between interatomic interactions and energy band evolution. The most stable CuInSe2/AlP heterostructures have “spike-like” band offsets, with the one terminated as Se-Al characterized by a flat conduction band offset of 12 meV. This comes from the strong “Cu d-Se p” states hybridization. The maximum conversion efficiencies of the “absorber-buffer” heterostructure and pure absorber have been studied as well.
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