In Situ Fabricated Perovskite Nanocrystals: A Revolution in Optical Materials

Abstract

in bulk halide perovskites, long carrier diffusion length, and an absorption range covering the visible solar spectrum, collectively enable the high performance of photo electricity conversion. Compared to the bulk materials, perovskite nanocrystals or quantum dots (usually denoted as PNCs or PQDs) show obvious excitonic features with enhanced photoluminescence (PL) properties due to the well-known size-dependent quantum confinement effects. [14][15][16][17] The combination of color saturated emissions, super high quantum yield (QY), as well as easy processing inspired the intensive exploration of PNCs as light emitters, which is now under spotlights in the field of optical materials.The first perspective aim of PNCs is to alternate the state-of-the-art CdSe or InP quantum dots (QDs) as new generation luminescence materials. [18,19] As shown in Figure 1, these QD materials have been well demonstrated to be potential functional components for photonic and optoelectronic applications, and are currently on the way to industrialization. [20][21][22][23] Specifically, QDs can be employed as fluorescence labels, [24] laser gain media, [25] LED phosphors, [26] and down-shifting films for LCD backlights. [27,28] They can also be processed into thin film for optoelectronic devices including solar cells, [29] photodetectors, [30,31] transistors [32] and LEDs. [33] The PNCs outcompete these conventional QDs in terms of narrower full width at half maximum (FWHM) and low fabrication cost, but most importantly, the ease of in situ preparation. [34,35] Herein, this progress report highlight the developments of in situ fabricated PNCs.Colloidal semiconductor QDs are typically synthesized ex situ in flasks by hot injection method, stabilized by surface ligands. [36][37][38][39] To incorporate such solution based materials into applications usually requires purification, redispersion and surface engineering. For instance, ligand exchange is often employed to disperse QDs into aimed solvent, inducing defects that inevitably derogating the PLQYs. [40] Moreover, the organic ligands themselves also suffer from the risk of disabsorbing, reducing the stability of the QDs and thus the final devices. [41] Because halide perovskite are ionic compounds that can be well dissolved into polar solvents, PNCs can be fabricated through either ex situ routes in flask or in situ strategies on substrates. The in situ fabricated PNCs are adaptable to devices integration due to their scalable and low-cost manufacturing. In this regard, more and more efforts have been made in terms of the controlling synthesis, physical properties and device applications of PNC materials.After over 30 years of development, colloidal quantum dots have now become mature luminescent materials in photonic and optoelectronic operations and start to hit the market. The emerging perovskite nanocrystals are expected to promote large-scale commercialization due to their superior optical properties as well as low cost and easy fabrication. This progress report is focused on the...

Spray‐Assisted Coil–Globule Transition for Scalable Preparation of Water‐Resistant CsPbBr3@PMMA Perovskite Nanospheres with Application in Live Cell Imaging

“…Lead halide perovskites have emerged as promising candidate materials in optoelectronic and photovoltaic devices due to their excellent optoelectronic properties, such as high photoluminescent quantum yield (PLQYs) and excellent charge transport properties . Among them, nanosized organometal and all‐inorganic perovskite quantum dots (PQDs) are found to possess ultrahigh PLQYs (CsPbBr 3 > 90%), narrow full‐width‐at‐half‐maximum (FWHM, ≈20 nm), and tunable emission wavelengths covering the entire visible region (400–760 nm) by changing their composition .…”

Highly Efficient and Stable Inorganic Perovskite Quantum Dots by Embedding into a Polymer Matrix

“…The all‐inorganic perovskite quantum dots (QDs) of the formula CsPbX 3 (X=Cl, Br, I) have specifically attracted considerable attention due to their narrow emission line width, size‐dependent luminescence behavior, covering the visible to near infrared range (400–800 nm), as well as superior photoluminescence quantum yield (PL QY) . These advantages make them the ideal candidates for light‐emitting diode (LED), lasers, solar cells, and photodetector .…”

Metal halide perovskite nanocrystals and their applications in optoelectronic devices

“…The polymer matrix should be chosen to have the same solvent solubility as the perovskite precursor to ensure efficient phase mixing, strong interaction with the perovskite, and dielectric properties that should be compatible with the operation of the electroluminescence (EL) device. 155 Taking advantage of the phenomenon that the polymer swells in a good solvent, Dong and colleagues have invented a swelling-deswelling method based on a polymer film. As shown in Figure 6F, the swelling process is carried out by spin coating or brushing a DMF precursor solution onto a target polymeric substrate, selecting a typical commercial polymer having a certain swelling capacity in DMF, such as polystyrene, poly(methyl methacrylate) (PMMA), or polycarbonate, and brings the perovskite precursor solute into the polymer matrix during the swelling process.…”

“…Both the blend spin coating and the controlled drying belong to the in situ preparation in the polymer matrix, which utilizes a method of directly mixing the polymer with the precursor solution or a tape casting method in the industry, and the latter utilizes controllable evaporation of DMF to separate the crystallization process of polyvinylidene fluoride matrix and perovskite QDs (Figure D,E). The polymer matrix should be chosen to have the same solvent solubility as the perovskite precursor to ensure efficient phase mixing, strong interaction with the perovskite, and dielectric properties that should be compatible with the operation of the electroluminescence (EL) device . Taking advantage of the phenomenon that the polymer swells in a good solvent, Dong and colleagues have invented a swelling‐deswelling method based on a polymer film.…”