Photoluminescence induced by twinning interface in CdS nanocrystals

The photoluminescence (PL) spectra acquired from CdS nanocrystals encapsulated with oleic acid synthesized by a two-phase approach exhibit two fine features, including a narrow peak arising from near-band edge emission and a broader one composed of two subpeaks at slightly lower energy. Solvent effects suggest that the surface defect states on the nanocrystals are not the origin of this broad PL band. High-resolution transmission electron microscopy examinations and density function theory calculation reveal that the broad low-energy PL band stems from twinning interfaces in the CdS nanocrystals.