Nanoimprinted 2D‐Chiral Perovskite Nanocrystal Metasurfaces for Circularly Polarized Photoluminescence

Abstract

The versatile hybrid perovskite nanocrystals are one of the most promising materials for optoelectronics in virtue of their tunable bandgaps and high photoluminescence quantum yields. However, their inherent crystalline chemical structure limits the chiroptical properties achievable with the material. The production of chiral perovskites has become an active field of research for its promising applications in optics, chemistry or biology. Typically, chiral halide perovskites are obtained by the incorporation of different chiral moieties in the material. Unfortunately, these chemically modified perovskites have demonstrated moderate values of chiral photoluminescence so far. Here we introduce a general and scalable approach to produce chiral photoluminescence from arbitrary nano-emitters assembled into 2D-chiral metasurfaces. The fabrication via nanoimprinting lithography employs elastomeric molds engraved with chiral motifs covering millimeter areas that are used to pattern two types of unmodified colloidal perovskite nanocrystal inks: green-emissive CsPbBr3 and red-emissive CsPbBr1I2. The perovskite 2D-metasurfaces exhibit remarkable photoluminescence dissymmetry factors (glum) of 0.16 that can be further improved up to glum of 0.3 by adding a high refractive index coating on the metasurfaces. This scalable approach to produce chiral photoluminescent thin films paves

Chiral Lattice Resonances in 2.5-Dimensional Periodic Arrays with Achiral Unit Cells

“…More recently, lattice resonances have begun to be explored for applications involving chirality. − A material object is said to be chiral when it cannot be superimposed on its mirror image, or enantiomer, by rotations and translations . Many important biomolecules, such as sugars and amino acids, as well as drugs used in medicine, are chiral , and, in many cases, only one enantiomer is active while the other is inactive or even harmful. , Therefore, the precise enantioselective detection, identification, and manipulation of chiral molecules with light-based technologies is a key goal in biosensing and photochemistry, which requires the development of optical systems with strong chiral responses. − These systems are also very relevant for the implementation of optical elements capable of controlling and modifying the polarization state of light. − …”

Tunable Periodic Nanopillar Array for MAPbI3 Perovskite Photodetectors with Improved Light Absorption

“…In recent years, various methods such as orthogonal lithography, , nanosphere lithography, − chemical stripping lithography, self-collapse lithography, nanoimprint methods, − and photolithography have been developed to prepare large-area submicrometer patterns. These strategies have low cost and high repeatability and have been widely used to fabricate nanostructured devices. − For instance, Wang et al realized a high-performance patterned perovskite photodetector at the nanometer level through nanoimprint lithography; the crystallinity and optical properties of the perovskite have been improved, which contribute to higher mobility, longer diffusion length, and better photon absorption .…”

Engineering and Controlling Perovskite Emissions via Optical Quasi‐Bound‐States‐in‐the‐Continuum

“…[34][35][36][37][38][39][40] By coupling the optical modes of an antenna system to the excitonic states of emitters, the optical response of perovskites can be tailored to achieve unique effects, such as enhanced luminescence, [41,42] optical encoding, [40,43] polarization tuning [44,45] and highly tunable emission chirality. [46,47] However, despite these advancements and the attraction of such an approach, the maximum spectral shift reported to date is only 8 nm (≈20 meV) via coupling to a microcavity, at the expense of approximately fivefold reduction of the PL intensity. [48] One potential approach to address these challenges is the use of quasi bound-states-in-the-continuum (q-BIC) mode and it is derived from bound-states-in-the-continuum (BICs), which are wave solutions found within a radiative continuum but are entirely isolated from it.…”