A Novel and Cost-Effective CsVO3 Quantum Dots for Optoelectronic and Display Applications

Abstract

Quantum dots (QDs) have an unparalleled ability to mimic true colors due to their size-tunable optical and electronic properties, which make them the most promising nanoparticles in various fields. Currently, the majority of QDs available in the market are cadmium, indium, and lead-based materials but the toxicity and unstable nature of these QDs restricts their industrial and practical applications. To avoid using heavy metal ions, especially cadmium, the current research is focused on the fabrication of perovskite and vanadate QDs. Herein, we report the facile synthesis of a novel and cost-effective CsVO₃ QDs for the first time. The sizes of the CsVO₃ QDs produced were tuned from 2 to 10 nm by varying the reaction temperature from 140 to 190 °C. On increasing QD size, a continuous red shift was observed in absorption and emission spectra, signifying the presence of quantum confinement. In addition, along with CsVO₃ QDs, the CsVO₃ nanosheets self-assembled microflower-like particles were found as residue after the centrifugation; the X-ray diffraction indicated an orthorhombic structure. Under 365 nm excitation, these CsVO₃ microflower-like particles exhibited broad emission with CIE coordinates in the white emission region. The acquired results suggest that CsVO₃ QDs may represent a new class of cadmium-free materials for optoelectronic and biomedical applications.

Keywords: CsVO3 quantum dots; hotplate synthesis; quantum confinement effect; tunable emissions.

Figure 1

(a–c) SEM and TEM images and SAED pattern of CsVO₃ nanosheets self-assembled microflower-like particles. (d,e) EDX spectrum and the corresponding TEM image of CsVO₃ QDs. (f–j) EDS spectrum, SEM image, and the elemental mapping of a CsVO₃ microflower-like particle.

Figure 2

(a–c) TEM images of CsVO₃ QDs synthesized at 140, 170, and 190 °C, respectively. (d,e) Digital photos of QDs and microflower-like particles under day light and UV light. (f,g) XRD patterns of CsVO₃ powder samples at different reaction temperatures and (f)(i–vi) the corresponding SEM images of the CsVO₃ samples. (h,i) Absorption spectra and corresponding Tauc plots of CsVO₃ QDs synthesized at different temperatures.

Figure 3

(a) Schematic illustration of quantum confinement effect in CsVO₃ QDs, (b,c) digital photographs of CsVO₃ QDs synthesized at different reaction temperatures in the absence and presence of UV light.

Figure 4

(a) Luminescence spectra of CsVO₃ QDs synthesized at different reaction temperatures from 140 to 190 °C, (b) PL emission spectrum of microflower-like CsVO₃ particles excited at 365 nm, and (c) CIE chromaticity coordinates of CsVO₃ QDs and microflower-like particles ((1–6) CsVO₃ QDs and (7) CsVO₃ microflower-like particles).