Solving the Synthetic Riddle of Colloidal 2D PbTe Nanoplatelets with Tunable Near-Infrared Emission

TL;DR

This paper presents a novel synthesis method for 2D PbTe nanoplatelets with tunable near-infrared emission, expanding the family of lead chalcogenide 2D materials for photonic applications.

Contribution

It introduces a direct aminophosphine-based synthesis route for 2D PbTe nanoplatelets with controllable photoluminescence properties, overcoming previous synthetic challenges.

Findings

Achieved synthesis of 2D PbTe NPLs with PL emission at 910-1460 nm

Demonstrated control of PL position via Pb:Te ratio

Confirmed 2D geometry and superlattice formation

Abstract

Near-infrared emitting colloidal two-dimensional (2D) PbX (X=S, Se) nanoplatelets have emerged as interesting materials with strong size quantisation in the thickness dimension. They act as model systems for efficient charge carrier multiplication and hold potential as intriguing candidates for finer-based photonic quantum applications. However, synthetic access to the third family member, 2D PbTe, remains elusive due to a challenging precursor chemistry. Here, we report a direct synthesis for 2D PbTe nanoplatelets (NPLs) with unable photoluminescence (PL, 910-1460 nm (1.36-0.85 eV), PLQY 1-15 %), based on aminophosphine precursor chemistry. Ex-situ transamination of tris(dimethylamino)phosphine telluride with octylamine is confirmed by 31P NMR and yields a reactive tellurium precursor for the formation of 2D PbTe NPLs at temperatures as low as 0 {\deg}C. The PL position of the PbTe NPLs is unable by controlling the Pb:Te ration in the reaction. GIWAXS confirms the 2D geometry of the NPLs and the formation of superlattices. The importance of a post-synthetic passivation of the PbTe NPLs by PbI2 to ensure colloidal stability of the otherwise oxygen sensitive samples is supported by X-ray photoelectron spectroscopy. Our results expand and complete the row of lead chalcogenide-based 2D NPLs, opening up new ways for further pushing the optical properties of 2D NPLs into the infrared and toward technologically relevant wavelengths.