Synthesis of colloidal Zn(Te,Se) alloy quantum dots

Colloidal Zn(Te_1-xSe_x) quantum dots (QDs), which are highly mismatched semiconductor alloys, were synthesized by the hot injection of an organometallic solution, and the composition and size dependence of their optical gap were studied together with the theoretical calculation using the finite-depth-well effective mass approximation. The optical gaps exhibited considerable negative deviation from the mole fraction weighted mean optical gaps of ZnTe and ZnSe, i.e. a large optical gap bowing was observed, similar to the bulk and thin-film alloys. The composition and size dependence of optical gaps agreed well with theoretically calculated ones employing a bowing parameter similar to that of the bulk alloys; therefore, the extent of the optical gap bowing in these alloy QDs is concluded to be the same as that in bulk and thin-film alloys. The optical gaps of Zn(Te_1-xSe_x) QDs with diameters of 3.5-5 nm, where x ∼ 0.35, were close to the energy corresponding to green light, indicating that those QDs are very promising as green QD-phosphors.