Controllable Layer-By-Layer CdSe/ZnS Quantum-Dot Thin Films for Enhanced Performance of Light-Emitting Diodes and Photodetectors

We developed a promising deposition method for fabricatingcontrollablelayer-by-layer (LbL) quantum-dot (QD) structures. We introduced aspray coating method to induce desired properties of QD thin filmsas well as to control the thickness of QD layers. An intermediateheat treatment was applied between spray pass cycles to induce rapidevaporation of the surface ligands and solvent in the QD solution,which successfully prevents the formation of clusters on spray-coatedQD (Sr-QD) films. Furthermore, we observed that the LbL structureof Sr-QDs has fewer surface defects and better crystallinity, leadingto improved performance of optoelectronic devices compared to conventionalsolution-processed devices. Thus, our study suggests that this spraycoating process enables detailed control of the properties and thicknessof the QD films due to the highly controllable LbL structure of QDmonolayers (MLs).