Photoluminescence in PbS nanocrystal thin films: Nanocrystal density, film morphology and energy transfer

TL;DR

This study investigates how the morphology and density of PbS nanocrystal thin films influence their photoluminescence, revealing temperature-dependent energy transfer mechanisms and the impact of nanocrystal packing.

Contribution

It demonstrates the relationship between film morphology, nanocrystal density, and photoluminescence behavior, highlighting energy transfer processes in PbS nanocrystal films.

Findings

Densely packed films show spectral narrowing and red-shift due to energy transfer.

Temperature affects photoluminescence intensity via back energy transfer.

Low-density films exhibit suppressed energy transfer effects.

Abstract

We show that photoluminescence properties of PbS nanocrystal thin films are directly related to film morphology and nanocrystal density. In densely packed PbS nanocrystal films, low-temperature donor-to-acceptor energy transfer is mainly responsible for the photoluminescence spectra narrowing and shift toward longer wavelengths. At elevated temperatures, back energy transfer is proposed to be responsible for an unusual photoluminescence intensity temperature dependence. In thin films with a low PbS nanocrystal density, the energy transfer is suppressed, and the effect is dramatically reduced.