Brightly Luminescent and Color-Tunable Colloidal CH₃NH₃PbX₃ (X = Br, I, Cl) Quantum Dots: Potential Alternatives for Display Technology

Abstract

Organometal halide perovskites are inexpensive materials with desirable characteristics of color-tunable and narrow-band emissions for lighting and display technology, but they suffer from low photoluminescence quantum yields at low excitation fluencies. Here we developed a ligand-assisted reprecipitation strategy to fabricate brightly luminescent and color-tunable colloidal CH3NH3PbX3 (X = Br, I, Cl) quantum dots with absolute quantum yield up to 70% at room temperature and low excitation fluencies. To illustrate the photoluminescence enhancements in these quantum dots, we conducted comprehensive composition and surface characterizations and determined the time- and temperature-dependent photoluminescence spectra. Comparisons between small-sized CH3NH3PbBr3 quantum dots (average diameter 3.3 nm) and corresponding micrometer-sized bulk particles (2-8 μm) suggest that the intense increased photoluminescence quantum yield originates from the increase of exciton binding energy due to size reduction as well as proper chemical passivations of the Br-rich surface. We further demonstrated wide-color gamut white-light-emitting diodes using green emissive CH3NH3PbBr3 quantum dots and red emissive K2SiF6:Mn(4+) as color converters, providing enhanced color quality for display technology. Moreover, colloidal CH3NH3PbX3 quantum dots are expected to exhibit interesting nanoscale excitonic properties and also have other potential applications in lasers, electroluminescence devices, and optical sensors.

Low‐Dimensional Perovskites: From Synthesis to Stability in Perovskite Solar Cells

“…[57] In addition, an alkyl-amine-assisted precipitation approach was introduced to prepare mixed-halide perovskite MAPbX 3 QDs with various Br/I and Br/Cl conditions, which featured an exciton binding energy of ≈375 meV, and an optical phonon energy of ≈42 meV. [58] The absorption and photoluminescence (PL) spectra were tunable from 400 to 750 nm by changing the halide ion composition, and the prepared materials exhibit high color saturation due to the relatively narrow emission line widths full-width-half-maximum (FWHM = 20-50 nm). In addition to exerting control over the halide ion composition, tuning the sizes of perovskite QDs offers another route to tuning their emission colors.…”

Strong Quantum Confinement and Fast Photoemission Activation in CH3NH3PbI3 Perovskite Nanocrystals Grown within Periodically Mesostructured Films

“…One of the most versatile strategies to tune the optical properties of a semiconductor consists in reducing its size until it becomes of the order of the exciton Bohr radius and quantum confinement effects arise. [1] Different methods have been developed to try to controllably diminish the size of methyl ammonium lead halide (MAPbX 3 , X = Cl, Pb, I) crystals, [2][3][4][5][6][7] motivated by the interest these perovskites generate in the field of optoelectronics. [8][9][10][11][12] Efforts in obtaining dispersions of hybrid organic-inorganic perovskite nanocrystals for optoelectronic applications have mainly focused on MAPbBr 3 and MAPbBr x I 3-x , as this allows achieving visible emission bands.…”

“…[4] More recently, powders of porous silica exhibiting a 2D hexagonal mesopore structure have been used as templates to synthesize MAPbI 3 nanocrystals. [14,15] This approach proved to be suitable to attain bright and stable emission whose spectrum could be controlled by the average pore size of the matrix.…”

Control of Emission Color of High Quantum Yield CH3NH3PbBr3 Perovskite Quantum Dots by Precipitation Temperature

“…In the present system, good solvent ( N ‐dimethylformamide, DMF) containing precursors and long‐chain ligands (typically with 18 carbon atom chains, which is longer than previously reported by the Pérez‐Prieto and co‐workers22 and Zhang et al 26. were injected into toluene as a bad solvent under vigorous stirring.…”