Quantum Dots in Glasses: Size‐Dependent Stokes Shift by Lead Chalcogenide

Abstract

Size‐dependent S tokes shift of P b S quantum dots ( QD s) formed in the glasses was investigated. P b S QD s with diameters of 3.5 nm to 13.3 nm were precipitated in silicate glasses with different S / P b ratios using the conventional thermal treatment method. Absorption and photoluminescence ( PL ) of P b S QD s were tuned from ~0.9 μm (1.38 eV) to ~2.3 μm (0.54 eV) by adjusting the diameters of P b S QD s from 3.5 nm to 13.3 nm. PL energies of QD s exhibited linear dependence on the absorption energies with a slope of 0.484 for P b S QD s with band gap energies larger than 0.98 eV, and the maximum Stokes shift was found to be 206.2 meV for 3.5 nm‐sized P b S QD s. For large P b S QD s with band gap energies smaller than 0.98 eV, Stokes shift was found to be ~20 meV or smaller. The size‐dependent Stokes shift indicated that surface defects made the main contribution and relative energy positions of these surface defects were strongly dependent on the size of P b S QD s.