Fabrication of core-shell-type copper indium selenide and zinc selenide composite quantum dots and their optical properties

We successfully fabricated core/shell-type composite QDs based on the ternary-CuInSe ₂. For the CuInSe ₂/ZnSe core/shell QDs, an enhanced photoluminescence (PL) emission intensity, such as 16% of the photoluminescence quantum yield (PLQY), and a blue-shift in the emission after the ZnSe coating, were observed. The increase in the PLQY was the result of an exchange of the surface capping ligand from the organic hexadecylamine to the inorganic ZnSe and the smoothing of the confining profile due to the alloying. The blue-shift was attributed to the shrinkage of the effective size of the core-CuInSe ₂ region due to the partial alloying of the core-CuInSe ₂ with the ZnSe-shell around their interfaces. For the inverted core/shell QDs, i.e., the nominally ZnSe/CuIn5Se8 core/shell QDs, they showed a red emission at 619 nm. The emission wavelength is the shortest among the previously reported QDs in Cu-In-Se system