Nanocrystals of Cesium Lead Halide Perovskites (CsPbX₃, X = Cl, Br, and I): Novel Optoelectronic Materials Showing Bright Emission with Wide Color Gamut

Abstract

Metal halides perovskites, such as hybrid organic–inorganic CH3NH3PbI3, are newcomer optoelectronic materials that have attracted enormous attention as solution-deposited absorbing layers in solar cells with power conversion efficiencies reaching 20%. Herein we demonstrate a new avenue for halide perovskites by designing highly luminescent perovskite-based colloidal quantum dot materials. We have synthesized monodisperse colloidal nanocubes (4–15 nm edge lengths) of fully inorganic cesium lead halide perovskites (CsPbX3, X = Cl, Br, and I or mixed halide systems Cl/Br and Br/I) using inexpensive commercial precursors. Through compositional modulations and quantum size-effects, the bandgap energies and emission spectra are readily tunable over the entire visible spectral region of 410–700 nm. The photoluminescence of CsPbX3 nanocrystals is characterized by narrow emission line-widths of 12–42 nm, wide color gamut covering up to 140% of the NTSC color standard, high quantum yields of up to 90%, and radiative lifetimes in the range of 1–29 ns. The compelling combination of enhanced optical properties and chemical robustness makes CsPbX3 nanocrystals appealing for optoelectronic applications, particularly for blue and green spectral regions (410–530 nm), where typical metal chalcogenide-based quantum dots suffer from photodegradation.

Excitation Intensity Dependence of Photoluminescence Blinking in CsPbBr3 Perovskite Nanocrystals

“…10 Recent Rietveld refinement and pair distribution function analyses of X-ray total scattering data confirm that the room temperature crystal structure of CsPbX 3 NCs is orthorhombic with the space group Pnma. 37 A dilute solution of the NCs in toluene was mixed with a 3% poly(methyl methacrylate)(PMMA)/toluene solution in a 1:1 ratio to help with dispersion and then drop-cast onto a UVgrade fused-silica coverslip.…”

“…9,10 Inorganic cesium lead halide, CsPbX 3 (X = Cl, Br, I), perovskite NCs exhibit compositiontunable narrow emission lines and high PLQYs even in the weak electronic confinement regime and without a passivating shell. 10 Metal chalcogenide NCs such as CdSe, in comparison, must be engineered with a passivating semiconductor shell, good ligand coverage, and at sizes comparable to or smaller than the Bohr exciton radius to achieve high PLQYs.…”

Aluminum‐Doped Cesium Lead Bromide Perovskite Nanocrystals with Stable Blue Photoluminescence Used for Display Backlight

“…Compared with traditional metal‐chalcogenide NCs, halide perovskites NCs possess unique characteristics of wide color tunability via postsynthesis anion exchange and good photochemical stability even without shell coating 2. In particular, all‐inorganic cesium lead halide (CsPbX 3 , X = Cl, Br, I) NCs deliver prominent optical‐gain signatures that combine the advantages of both quantum dots and halide perovskites: high color‐purity with narrow tunable photoluminescence (PL) emission, high quantum efficiency, and higher stability compared with their organic–inorganic hybrid counterparts 3. These features are ideal for achieving saturated colors and enriching the display or television color gamut, which make them an promising candidate for backlight applications.…”

Polymer-Enhanced Stability of Inorganic Perovskite Nanocrystals and Their Application in Color Conversion LEDs

“…[1][2][3][4] Of high interest are their remarkable optical properties such as non-linear absorption, stimulated emission and blinking behavior. 2,[5][6][7] Compared to classical Cd-based chalcogenide quantum dots (QDs), CsPbX 3 (X = Cl, Br, I) offer a very broad and easily adjustable composition versatility together with ample options for shape control, which allow tuning of their emission wavelength throughout the whole visible spectrum.…”

“…One is based on embedding the NCs post-synthetically into a polymeric matrix such as PMMA or polystyrene. 1,18,23 The second path, very recently taken is to modify or strengthen the ligand sphere post synthetically. Increased water stability was achieved by utilizing silsesquioxane to coat CsPbX 3 nanocrystals.…”