InP/ZnS/ZnS core quantum dots for InP luminescence and photoelectrochemical improvement

Indium phosphide quantum dots (InP QDs) is a promising alternative to traditional Quantum Dots (QDs), improving photoluminescence and other properties. We present the synthesis of ZnS/ZnS double shell QDs by the hot injection method. The diameter of QDs was increased from 3.56 nm for the InP core, 4.7 nm for InP/ZnS QDs (with one-time shelling) and 5.53 nm for InP/ZnS/ZnS (double shelling). This experience revealed that the surface morphology of the QDs has a more regular spherical form and is well dispersed. Moreover, the shell's growth results in a strong improvement of the luminescence. Which is due to the passivation of the surface states by shell comparing with ZnS QDs mono shell coating, with an emission peak of 680 nm. Additionally, to improve the photocurrent efficiency, we report the synthesis of nanostructured films by depositing InP QDs, InP/ZnS QDs, and InP/ZnS/ZnS QDs. Spin coating method was used on the surface of Titanium dioxide nanotubes TiO2 NTAs prepared by the electrochemical anodization process. Photoelectrochemical analyses show significant properties improvement of InP/ZnS/TiO2 and InP/ZnS/ZnS/TiO2 in comparison of InP/TiO2. The measurement shows a photocurrent density around 4 x 10(-6) mAcm-2 for the photoanode InP/ZnS/ZnS/TiO2. Which is almost six times higher than that measured on TiO2/InP QDs. This result is attributed to a good compromise between Quantum Dots and TiO2 NTAs.