Light-Driven Quantum Dot Dialogues: Oscillatory Photoluminescence in Langmuir-Blodgett Films

This study explores the self-assembly and optical properties of close-packed quantum dots (QDs) within Langmuir-Blodgett (LB) films, focusing on strain-driven interactions and potential inter-atom diffusion. Monolayers of yellow-emitting QD450 and red-emitting QD645 were subjected to continuous laser illumination, revealing significant inter-dot coupling effects and time-dependent photoluminescence (PL) dynamics. The exponential shifts in PL peak positions and broadening of emission spectra suggest strain-induced modulation of optical properties. Differences in Se/S mole ratios and anisotropic strain at the core/shell interfaces of the QDs are proposed to drive inter-atom diffusion, leading to localized structural and electronic changes. Additionally, nonlinear variations in band-gap energy under varying laser intensities highlight a complex interplay between strain, optical excitation, and material properties. These findings provide insights into strain-driven atomic rearrangements and their impact on the photophysical behavior of QD systems.