Towards Engineering Intrinsic Linewidths and Line-Broadening in Perovskite Nanoplatelets

TL;DR

This study uses advanced spectroscopy to understand and control the linewidths of perovskite nanoplatelets, revealing how geometric tuning can significantly reduce broadening effects and improve optical properties.

Contribution

The paper demonstrates control over intrinsic and extrinsic linewidths in perovskite nanoplatelets through geometric tuning, providing insights into their broadening mechanisms.

Findings

Decreasing nanoplatelet thickness reduces linewidths by up to 3-fold.

Homogeneously broadened exciton resonances observed in 3-layer nanoplatelets at room temperature.

Control of broadening mechanisms enables potential improvements in optical device performance.

Abstract

Perovskite nanoplatelets possess extremely narrow absorption and emission linewidths, which are crucial characteristics for many optical applications. However, their underlying intrinsic and extrinsic line-broadening mechanisms are poorly understood. Here, we apply multi-dimensional coherent spectroscopy to determine the homogeneous line-broadening of colloidal perovskite nanoplatelet ensembles. We demonstrate control of not only their intrinsic linewidths, but also control of various broadening mechanisms by tuning the platelet geometry. Remarkably, we find that decreasing nanoplatelet thickness by a single polyhedral layer results in a 2-fold reduction of the inhomogeneous linewidth and a 3-fold reduction of the intrinsic homogeneous linewidth to the sub-meV regime. In addition, our measurements suggest homogeneously broadened exciton resonances in 3-layer (but not necessarily 4-layer) nanoplatelets at room-temperature.