Templated‐Assembly of CsPbBr₃ Perovskite Nanocrystals into 2D Photonic Supercrystals with Amplified Spontaneous Emission

Abstract

Perovskite nanocrystals (NCs) have revolutionized optoelectronic devices because of their versatile optical properties. However, controlling and extending these functionalities often requires a light‐management strategy involving additional processing steps. Herein, we introduce a simple approach to shape perovskite nanocrystals (NC) into photonic architectures that provide light management by directly shaping the active material. Pre‐patterned polydimethylsiloxane (PDMS) templates are used for the template‐induced self‐assembly of 10 nm CsPbBr3 perovskite NC colloids into large area (1 cm2) 2D photonic crystals with tunable lattice spacing, ranging from 400 nm up to several microns. The photonic crystal arrangement facilitates efficient light coupling to the nanocrystal layer, thereby increasing the electric field intensity within the perovskite film. As a result, CsPbBr3 2D photonic crystals show amplified spontaneous emission (ASE) under lower optical excitation fluences in the near‐IR, in contrast to equivalent flat NC films prepared using the same colloidal ink. This improvement is attributed to the enhanced multi‐photon absorption caused by light trapping in the photonic crystal.

Solid‐State Red Laser with a Single Longitudinal Mode from Carbon Dots

“…Specifically, the former is attributed to C=C bonds in aromatic sp 2 domains, while the latter is likely due to various surface state transitions [37] . The PL emission spectra of R‐CD1 and R‐CD2 are very similar, both have a main peak at 608, and is characteristic of excitation‐independent emission, which is likely beneficial to the realization of ASE for CDs (Figures 2 a and S13) [38] . The aqueous solution emitted strong red light under 365 nm UV irradiation (Figure 2 a), with a PLQY as high as 65.5 % in the aqueous phase (Figure S5).…”

Micro–Nanostructure‐Assisted Luminescence in Perovskite Devices

“…Vila‐Liarte et al also used the common soft template‐assisted bottom‐up technique to self‐assemble the CsPbBr 3 perovskite nanocrystalline into 2D PCs. [ 113 ] The arrangement of PCs benefits the effective light coupling to the NC layer, thus increasing the electric field intensity in the perovskite film. Compared with the planar nanocrystalline film, the 2D PCs exhibited ASE with a threshold intensity of 10.9 mJ cm −2 , which was attributed to the enhancement of multiphoton absorption caused by light trapping scheme.…”

Functional Colloidal Assemblies Based on Superwettable Substrates

“…This method is applicable to a very wide range of material types on various substrates and even on non‐planar surfaces, requiring only small liquid volumes. Sandwich assembly systems are mainly based on physical confinement [ 210–224 ] and superwettability. [ 225–234 ] In the case of physical confinement, the channels are formed between flat and patterned substrates, which enable the generation of patterned colloidal assemblies, while superwettability‐based systems mainly rely on patterned substrates featuring periodically arranged micropillar‐structured silicon templates.…”