Solvent Modulation of Chiral Perovskite Films Enables High Circularly Polarized Luminescence Performance from Chiral Perovskite/Quantum Dot Composites

Abstract

Materials with circularly polarized luminescence (CPL) activity are promising in many chiroptoelectronics fields, such as for biological probes, asymmetric photosynthesis, information storage, spintronic devices, and so on. Promoting the value of the dissymmetry factor (g lum) for the CPL-active materials based on chiral perovskite draws increasing attention since a higher g lum value indicates better CPL. In this work, we find that, after being treated with a facile solvent modulation strategy, the chirality of 2D chiral perovskite films has been enhanced a lot, which we attribute to an increased lattice distortion degree. By forming chiral perovskite/quantum dot (QD) composites, the CPL-active material is successfully obtained. The calculated maximum |g lum| of these composites increased over 4 times after solvent modulation treatment (1.53 × 10–3 for the pristine sample of R-DMF and 6.91 × 10–3 for R-NMP) at room temperature. Moreover, the enhancement of the CPL intensity is ascribed to two aspects: one is the generation and transportation of spin-polarized charge carriers from chiral perovskite films to combine in the QD layer, and the other is the solvent modulation strategy to enlarge the lattice distortion of chiral perovskite films. This facile route provides an effective way to construct CPL-active materials. More importantly, this kind of composite material (chiral perovskite film/QD layer) can be easily applied for fabricating circularly polarized light-emitting diode devices for electroluminescence.

Chiral Carbon Dots and Chiral Carbon Dots with Circularly Polarized Luminescence: Synthesis, Mechanistic Investigation and Applications

“…The CPL produced by chiral inorganic chalcogenide semiconductor nanomaterials, chiral metal clusters, chiral perovskites and chiral lanthanide complexes is mainly due to circularly polarized fluorescence, and these types of optical media are uniformly dispersed in solvents or thin films [75–78] . In contrast, the CPL of chiral composites usually originates from circularly polarized scattering, which is mainly attributed to the size effect of such materials [79–83] . In general, CPL systems are constructed in two ways: the first is by using chiral molecules with endogenous luminescence properties, such as organic small molecules, metal complexes and supramolecular compounds; the second is in the form of “subject‐object”, i. e., the luminescent center is non‐chiral and exhibits endogenous chirality by combining with a chiral body or The second is the “subject‐object” form, in which the luminescent center is non‐chiral and induces chirality by binding to a chiral body, exhibiting endogenous chirality or forming a chemical bond to make the “subject‐object” molecule CPL active.…”

“…[75][76][77][78] In contrast, the CPL of chiral composites usually originates from circularly polarized scattering, which is mainly attributed to the size effect of such materials. [79][80][81][82][83] In general, CPL systems are constructed in two ways: the first is by using chiral molecules with endogenous luminescence properties, such as organic small molecules, metal complexes and supramolecular compounds; the second is in the form of "subject-object", i. e., the luminescent center is non-chiral and exhibits endogenous chirality by combining with a chiral body or The second is the "subject-object" form, in which the luminescent center is non-chiral and induces chirality by binding to a chiral body, exhibiting endogenous chirality or forming a chemical bond to make the "subject-object" molecule CPL active. Although the principles of circularly polarized fluorescence and circularly polarized scattering are different, both are quantified by CPL, and the asymmetry factor g lum of CPL can be expressed by equation (1):…”

Circularly Polarized Room-Temperature Phosphorescence with an Ultrahigh Dissymmetry Factor from Carbonized Polymer Dots by Stacked Chiral Photonic Films

“…Circularly polarized luminescence (CPL) materials are emerging and attractive optical functional materials, which have received extensive attention in the fields of 3D display, − optical sensors, − information data storage, and optoelectronic devices. , To quantificationally evaluate the asymmetricity of the CPL spectrum, the luminescence dissymmetry factor ( g lum ) is defined, which represents the ratio of the difference in intensity divided by the average total luminescence intensity: g lum = 2 × ( I L − I R ) / ( I L + I R ) where I L and I R are the intensities of the left and right circularly polarized emissions, respectively . According to eq , the maximum absolute value of g lum is 2.0.…”

Spatially Correlated Chirality in Chiral Two-Dimensional Perovskites Revealed by Second-Harmonic-Generation Circular Dichroism Microscopy

“…Lu’s group revealed the ubiquitous contributions of linear dichroism (LD) and linear birefringence (LB) to the chiroptical activity directly measured in chiral low-dimensional perovskites . Very recently, Wang and co-authors developed a solvent modulation strategy for enhancing the chirality of 2D perovskite thin films by increasing the degree of lattice distortion . Nevertheless, understanding the mechanism of chiroptical activity in chiral perovskites is still insufficient, which will hinder the construction of novel chiral perovskites for high-efficiency optoelectronic and spintronic applications.…”