Tip-induced strain, bandgap, and radiative decay engineering of a single metal halide perovskite quantum dot

TL;DR

This study introduces a novel tip-induced strain engineering method combined with TEPL spectroscopy to precisely control and reversibly tune the bandgap and emission properties of single perovskite quantum dots at the nanoscale.

Contribution

The paper demonstrates the first single-emitter level manipulation of perovskite quantum dots using a plasmonic tip to induce strain and modify optical properties.

Findings

Achieved a bandgap shift of up to 62 meV in single pQDs.

Reversible dynamical bandgap tuning through tip-induced strain.

Enhanced photoluminescence quantum yield up to 10^5 for strained pQDs.

Abstract

Strain engineering of perovskite quantum dots (pQDs) enables widely-tunable photonic device applications. However, manipulation at the single-emitter level has never been attempted. Here, we present a tip-induced control approach combined with tip-enhanced photoluminescence (TEPL) spectroscopy to engineer strain, bandgap, and emission quantum yield of a single pQD. Single CsPbBr$_{x}$I$_{3-x}$ pQDs are clearly resolved through hyperspectral TEPL imaging with $\sim$10 nm spatial resolution. The plasmonic tip then directly applies pressure to a single pQD to facilitate a bandgap shift up to $\sim$62 meV with Purcell-enhanced PL quantum yield as high as $\sim$10$^5$ for the strain-induced pQD. Furthermore, by systematically modulating the tip-induced compressive strain of a single pQD, we achieve dynamical bandgap engineering in a reversible manner. In addition, we facilitate the quantum dot coupling for a pQD ensemble with $\sim$0.8 GPa tip pressure at the nanoscale. Our approach presents a new strategy to tune the nano-opto-electro-mechanical properties of pQDs at the single-crystal level.