Optical and electrical properties of quantum composite of polyvinyl alcohol matrix with CdSe quantum dots

Abstract

CdSe quantum dots (QDs) were prepared by a simple green route with CdSO4 and Na2SeSO3 in aqueous solution. The as-prepared citrate-capped CdSe QDs were characterized by XRD and TEM. Single-phase cubic zinc blende structure was confirmed with uniform size and highly crystallized QDs of CdSe. Composite based on the decoration of polyvinyl alcohol (PVA) matrix with CdSe QDs was fabricated by the solution casting process. UV–vis absorption spectra confirmed the formation of composites with a refractive index which was enhanced with CdSe weight fraction wt%. Photoluminescence properties of CdSe@PVA composites at different CdSe QD weight fractions (wt%) were recorded. The emission colors were controlled by CdSe wt% and tuned with its particle size. The a.c. electrical conductivity was measured at temperatures from 300 to 493 K and at frequencies from 50 to 100 kHz. The dielectric constant was enhanced after inserting CdSe QDs into PVA matrix. The a.c. electrical conductivity results showed that PVA and CdSe@PVA composite films follow the overlap large polarons (OLP) model. Also, the activation energy (Ea) decreased with the presence of CdSe in PVA polymer relative to pure PVA.