Efficient separation and low thermalization of hot carriers in natural superlattice of BiOCuCh (Ch = S, Se, Te)

Abstract

The optic-electronic response is usually limited by poor electron–hole separation and phonon thermalization. Here, we show that natural superlattice materials with charged layers in BiOCuCh (Ch = S, Se, Te) can effectively suppress bulk carrier recombination and dissipation from phonon. The photogenerated hot carriers in BiOCuCh are separated by the intrinsic p–n junction naturally composed of the [Cu2Ch2]2− and [Bi2O2]2+ layers, and transport occurs with high speed within the two layers. Moreover, its dissipation can be substantially reduced because the interlayer coupling leads to low phonon thermalization. As a result, these materials both show prominent response to full-spectrum solar lights and resemble cocatalysts in their characteristics. Because of these merits, these oxychalcogenides provide a penetration point up-and-coming platform for the exploration of materials with an extraordinary optoelectric response.