Mid-IR band gap engineering of CdxPb1?xS nanocrystals by mechanochemical reaction

摘要

Composition-tunable ternary Cdx Pb 1?xS nanocrystals (NCs) are very important materials for remote sensing and detecting in the infrared (IR) wavelength region. They are, however, almost exclusively prepared by wet chemical routes which lead to surface-capped nanoparticles. The surface capping molecules could move their absorption peaks from mid-IR to near IR wavelength region. However, surface clean Cdx Pb 1?xS nanocrystals (NCs) would demonstrate intrinsic optical spectrum in the mid-IR region. Herein, we present a physical mechanical alloying (MA) process being applied to prepare tens of grams of surface clean Cdx Pb 1?xS nanocrystals within the composition range of x = 0.0 to 0.4. The average particle size is smaller than 9 nm. The as-milled nanocrystals are chemically homogenous. The Cdx Pb 1?xS nanocrystals show a continuous lattice contraction with Cd content. There is an exponential indirect band gap-composition relationship. This MA method shows the ability to continuously and precisely tune the band gap energies of ternary Cdx Pb 1?xS semiconductor nanocrystals from mid-IR region (2638 nm) to NIR wavelength region (1240 nm) through chemical composition.