Charge Separation in Type-II Semiconductor Heterodimers

Highly efficient photoenergy conversion in semiconductor nanoparticle heterostructures requires the formation of epitaxial heterointerfaces and band alignment engineering. This requirement has led to attention being given to recent advances and prospects in the charge separation properties of type-II semiconductor heterodimers composed of chalcogenide–chalcogenide blends. Type-II semiconductor heterodimers with a staggered alignment of band edges at the heterointerface can be synthesized by seeded growth or ion exchange to promote the spatial charge separation between electrons and holes in different parts of the heterostructure. Special attention has been given to CdS–Cu2–xS (0 ≤ x ≤ 0.0625) and CdS–CdTe combinations where CdS is a commonly used n-type semiconductor and both Cu2–xS and CdTe are proper p-type semiconductors that are used as light absorbers in heterojunction solar cells.