Sub‐30 nm 2D Perovskites Patterns via Block Copolymer Guided Self‐Assembly for Color Conversion Optical Polarizer

Abstract

Despite the remarkable advances made in the development of 2D perovskites suitable for various high‐performance devices, the development of sub‐30 nm nanopatterns of 2D perovskites with anisotropic photoelectronic properties remains challenging. Herein, a simple but robust route for fabricating sub‐30 nm 1D nanopatterns of 2D perovskites over a large area is presented. This method is based on nanoimprinting a thin precursor film of a 2D perovskite with a topographically pre‐patterned hard poly(dimethylsiloxane) mold replicated from a block copolymer nanopattern consisting of guided self‐assembled monolayered in‐plane cylinders. 1D nanopatterns of various 2D perovskites (A′2MAn−1PbnX3n+1,A′ = BA, PEA, X = Br, I) are developed; their enhanced photoluminescence (PL) quantum yields are approximately four times greater than those of the corresponding control flat films. Anisotropic photocurrent is observed because 2D perovskite nanocrystals are embedded in a topological 1D nanopattern. Furthermore, this 1D metal‐coated nanopattern of a 2D perovskite is employed as a color conversion optical polarizer, in which polarized PL is developed. This is due to its capability of polarization of an incident light arising from the sub‐30 nm line pattern, as well as the PL of the confined 2D perovskite nanocrystals in the pattern.

2D Materials for Integrated Optical Polarizers

“…An optical polarizer based on 2D perovskites was also demonstrated, which enabled the conversion of deep ultraviolet incident light into polarized photoluminescence of the 2D perovskite at visible wavelengths (Figure 3h) [75]. The polarizer was consisted of a periodic sub-30-nm 2D BA2MA2Pb3Br10 perovskite line pattern, which was fabricated by nanoimprinting a precursor film of the 2D perovskite via spin coating on a silicon substrate with a topographically prepatterned hard PDMS mold.…”

“…The ability to pattern 2D materials can also introduce more complex polarization functionalities that go beyond what traditional polarization mechanisms can provide. For example, uniformly spaced and well-aligned free-standing 2D materials patterns are needed for 2D-material-based wire grid polarizers to achieve a high PER [75,88], and a THz spatial light optical polarizer with graphene patches in different patterns can convert the linearly polarized waves into different polarization states [87]. So far, many approaches have been employed to pattern 2D materials, such as laser patterning, lithography, nanoimprinting, inkjet printing, and focused ion beam (FIB) milling [134][135][136][137].…”

Integrated optical polarizers based on novel 2D materials

“…In addition, the intrinsic non-centrosymmetry of the crystal structures endow perovskites with strong optical anisotropy for the detection or emission of polarized light [73,74], which forms their applications to polarization selective devices. Moreover, perovskite materials demonstrate environmental stability since the organic components can provide hydrophobicity and mechanical flexibility, while the inorganic parts offer structural robustness and chemical resistance [75].…”

“…An optical polarizer based on 2D perovskites was also demonstrated, which enabled the conversion of deep ultraviolet incident light into polarized photoluminescence of the 2D perovskite at visible wavelengths (Fig. 3h) [75]. The polarizer was consisted of a periodic sub-30-nm 2D BA2MA2Pb3Br10 perovskite line pattern, which was fabricated by nanoimprinting a precursor film of the 2D perovskite via spin coating on a silicon substrate with a topographically prepatterned hard PDMS mold.…”

“…h is reprinted with permission from ref. [75] Copyright 2023 Wiley-VCH. i is reprinted with permission from ref.…”