Tip-Induced Strain Engineering of a Single Metal Halide Perovskite Quantum Dot.

Lee, Hyeongwoo; Woo, Ju Young; Park, Dae Young; Jo, Inho; Park, Jusun; Lee, Yeunhee; Koo, Yeonjeong; Choi, Jinseong et al. · ACS Nano · 2021

basic_science · Level V

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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 the emission quantum yield of a single pQD. Single CsPbBr<sub><i>x</i></sub>I<sub>3-<i>x</i></sub> 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 increase as high as ∼10<sup>5</sup> 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 ∼0.8 GPa tip pressure at the nanoscale estimated theoretically. Our approach presents a strategy to tune the nano-opto-electro-mechanical properties of pQDs at the single-crystal level.