Organic Metal Halogenide Netted Colloidal Quantum Dot Superlattice

The bottom-up assembly of colloidal quantum dots (CQDs) into superlattice structures is attractive for leveraging nanocrystal quantum features into films and optoelectronic devices. However, current CQD superlattices often require tedious control of the assembly kinetics, and they suffer from either excessively long interfacial distances, which impede carrier transport, or facet fusion, which brings high defect density. These hinder CQD superlattice applications in optoelectronic devices, where low defect density and large carrier diffusion lengths are essential. Herein, inspired by the growth of a two-dimensional (2D) perovskite layer, a class of aromatic organic cation ligands is adopted to stabilize CQDs and induce close and ordered packing of CQDs into a superlattice netted by an organic metal halogenide (QD@OMH), giving rise to a high carrier diffusion length (>250 nm) for lead sulfide (PbS) CQD film. The superlattice-based infrared photodetectors achieve a responsivity of 0.663 A W-1 at 1560 nm and an order-of-magnitude reduction in noise current density, yielding a detectivity exceeding 1013 Jones. Furthermore, the infrared light-emitting diodes achieve a high radiance (22.4 W sr-1 m-2) and an operational T90 lifetime exceeding 200 h under continuous operation at peak luminance.