Realization of controlling the band alignment via atomic substitution

Search for semiconductors with proper band edge positions for given reactions is a challenging problem. Here, taking chevron-shaped graphene nanoribbon (CGNR) as an example, we develop a promising general model for artificially controlling material’s band alignment. We show that, depending on the position of substitution site, nitrogen produces different effects. In particularly, edge substitution actually almost does not alter the band gap of CGNR. More remarkably, by increasing edge substitution ratio, a linearly downshifting of the band alignment of CGNR occurs. Our results provide a new perspective on band alignment: material’s band alignment can be continuously and precisely shifted, without affecting the magnitude of the band gap, via substitution of well-selected impurity atoms for well-selected sites. This is a major advancement in band alignment, which is of fundamental importance in electronics, optoelectronics and photocatalysis.