The structure and luminescence properties of Pb1-xNbxSe QDs prepared via 4,4-bis(carbazole-9-yl)biphenyl assisted microwave approach for NIR-QLED applications

Abstract

Herein, a series of Pb 1-x Nb x Se QDs were prepared via 4,4-bis(carbazole-9-yl)biphenyl assisted microwave approach for NIR-QLED applications. The structural phases and crystalline dimension were accentuated by XRD. The diffraction patterns showed a cubic phase at all Nb-contents. The TEM measurements scrutinized the increase of the particle size from 2.4 ± 0.2 nm to 9.9 ± 0.3 nm with increasing the Nb-amounts. The high resolution transmission electron microscopy (HRTEM) measurements inspected that the d-spacing increases with the increase of the Nb-atoms concentration and the prepared nanocrystals tend to grow along the (111) direction. The energy-dispersive X-ray spectroscopy (EDS) and the X-ray photoelectron spectroscopy (XPS) measurements revealed the stoichiometry of the prepared nanocrystals and the oxidation states of the Nb, Pb, and Se ions are 2+, respectively. The optical absorbance spectroscopy measurement of Pb 1-x Nb x Se QDs revealed the ability of Nb-atoms to modify the bandgaps of PbSe QDs from 1.62 eV to 1.28 eV. The luminescence intensity is increased by 10 folds and the spectral bandwidth is decreased due to the doping of PbSe QDs with Nb-atoms. The doping of PbSe QDs with Nb-atoms increases the quantum yield to 75% and decreases the Stokes shift by 9 folds. These unique characteristics may enable the Pb 1-x Nb x Se QDs to be employed for the manufacture of highly luminescent NIR-QLED devices. • A new series of Nb 1-x Pb x Se QDs was prepared using microwave approach. • The Nb 1-x Pb x Se nanocrystals have face centered cubic crystal structure. • The Nb 1-x Pb x Se QDs showed high monodisperse nanoparticles. • The Nb-dopant improved the PL intensity and narrowing the emission bandwidth. • The developed Nb 1-x Pb x Se may be served as highly luminescent NIR-QLED.