Tunable Photoluminescence Wavelength of Chalcopyrite CuInS2-Based Semiconductor Nanocrystals Synthesized in a Colloidal System

Chalcopyrite-type CuInS2-based alloyed fluorescent nanocrystals (NCs), which contain no regulated heavy metal ions, were synthesized by heating an organometallic solution to demonstrate optical property tunability. Introduction of Zn into the CuInS2 system enhanced their photoluminescence (PL) intensity. The resultant particles were 3−6 nm; they varied with experimental conditions and were discrete and colloidally stable. The band-gap energy and PL wavelength of Zn-Cu-In-S (ZCIS) NCs varied with Zn content and particle size. Their PL was controllable within 570−800 nm by altering the band-gap energy. Furthermore, indium substitution with gallium was shown to control band-gap energy toward ∼3.1 eV, 500 nm of PL wavelength. In addition, ZnS coating of this nanocrystal can approximately double the PL strength. Finally, surface treatment with mercaptoundecanoic acid dispersed hydrophilic ZCIS NCs into water.