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

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 tipenhanced 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 ∼10 nm spatial resolution. The plasmonic tip then directly applies pressure to a single pQD to facilitate a bandgap shift up to ∼62 meV with Purcell-enhanced PL quantum yield as high as ∼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 ∼0.8GPa 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.