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Manganese-doped colloidal indium phosphide quantum dots with a thin zinc sulfide shell have been synthesized. Nanoclusters were fabricated based on the obtained nanocrystals. The effect of doping of nanocrystals on the process of Förster resonance electronic excitation transfer and the spectral and luminescent properties of nanoclusters was studied for the first time. It has been shown that the luminescence of such clusters radically differs from the luminescence of undoped clusters and depends on the size distribution of nanoparticles included in the nanoclusters. It is shown that the composition of particles participating in Förster transport depends on the time point of observation. [ABSTRACT FROM AUTHOR]

Colloidal quantum dots of CsPbBr3 perovskites have been synthesized. The average size and polydispersity of nanocrystals were determined to be 8.3 nm and 16%, respectively. Thin films were made based on the obtained nanocrystals using drop-casting and spin-coating methods. The charge carrier transport process was studied using the technique of femtosecond laser pump–probe spectroscopy. An interpretation of the shift in the bleaching peak as a function of time is proposed. The mobility of charge carriers in films has been estimated using the Einstein–Smoluchowski equation. [ABSTRACT FROM AUTHOR]

The physical mechanism of the quantum size effect, which determines the main feature of the size dependence of absorption and photoluminescence spectra of nanoparticles of semiconductor materials, is outlined, and the effects of multiexciton generation and luminescence blinking of colloidal quantum dots are discussed. [ABSTRACT FROM AUTHOR]

Nanoclusters of colloidal quantum dots (CQDs) are considered, the luminescent properties of which largely determine the electronic-excitation transport processes described by the Förster mechanism of inductive resonance interaction of CQDs. A simple theoretical model is proposed taking into account the Kennard–Stepanov relation, with the help of which numerous experimental results are analyzed. [ABSTRACT FROM AUTHOR]

A brief review of the well-known laws and rules of photoluminescence is given, and it is shown that these laws usually do not hold for CQD solutions. It has been shown that this is due to a special mechanism for the formation of the luminescent properties of CQDs. The derivation of a new universal law of photoluminescence, applicable to any type of luminophores, which has recently been substantiated theoretically and verified experimentally using the example of CQDs, is presented. [ABSTRACT FROM AUTHOR]

The results of molecular dynamics simulation of the crystal structure of the currently most studied CQDs, based on cadmium selenide nanoparticles, are presented, and issues concerning the structure of the ligand shell of these nanoparticles, primarily made of trioctylphosphine (TOP) and trioctylphosphine oxide (TOPO) molecules, which act as a medium and as precursors in the chemical reaction that results in the formation of CQDs, are discussed in detail. [ABSTRACT FROM AUTHOR]

Various currently known methods for producing quantum dots are described in detail, including the most promising method of high-temperature colloidal synthesis (HTCS). Using the HTCS technique, it is possible to cope quite well with the task of obtaining a relatively perfect structure of colloidal quantum dots (CQDs) and achieve record-breaking narrow size distributions of CQDs. During the synthesis of nanoparticles, high-temperature annealing of their structure occurs. That is why this method has become so widespread and caused such a rapid increase in publication activity. [ABSTRACT FROM AUTHOR]

Mechanisms of homogeneous and inhomogeneous broadening of absorption and photoluminescence spectra of CQDs are discussed. The influence of the nature of solvents, their dielectric characteristics, and the type of stabilizing ligands on the luminescent properties of CQDs, including the luminescence blinking effect, is considered. [ABSTRACT FROM AUTHOR]

The article focuses on the development and application of colloidal quantum dots (CQDs), tracing their historical discovery and the advancement of synthesis methods, particularly high-temperature colloidal synthesis (HTCS). It discusses the physical mechanisms behind quantum size effects, the challenges in achieving high-quality luminescent properties, and new universal laws of photoluminescence applicable to CQDs.

To optimize photosensitive structures based on colloidal lead sulfide quantum dots, the rate and completeness of replacement in thin layers was studied using Fourier transform infrared spectroscopy on a multiple attenuated total internal reflection attachment. The rate of ligand replacement in a thin layer of colloidal lead sulfide quantum dots when replaced by iodide ion in different solvents was studied for the first time. A change in the composition of the shells of PbS nanoparticles under the influence of a number of solvents and when replacing them with thiocyanate ions was shown. For the first time, the replacement of the oleate ligand shell with pure formamide has been established. [ABSTRACT FROM AUTHOR]

A new architecture of photosensitive elements for the near- (0.7–1.4 μm) and short-wavelength (1.4–3.0 μm) infrared spectral ranges is proposed, which is based on hybrid nanostructures consisting of PbS colloidal quantum dots and ZnO and silver nanowire functional layers. Small-sized (12 × 12 μm) photosensitive elements with an energy barrier at the contact between layers of colloidal quantum dots with n- and p‑type conductivity have been studied. The I‒V characteristics, spectral dependences of optical absorption, and relative spectral photosensitivity Si(λ)/Si(λmax) of the barrier structures at room temperature have been examined. It is shown that the proposed architecture of the barrier structures ensures the photosensitivity in a wide spectral range from 0.4 to 2.0 µm. An excess of the average value of the relative spectral sensitivity Si(λ)/Si(λmax) by a factor of about 1.5 as compared with the values observed previously for the PbS colloidal quantum dot barrier nanostructures in the wavelength range of 0.9–1.85 μm has been found. [ABSTRACT FROM AUTHOR]

The integral current responsivity and detectivity of laboratory samples of IR photodetectors based on HgTe colloidal quantum dots were measured as functions of the thickness of the photosensitive layer. The layers were obtained by sequential deposition of quantum dot monolayers by dip-coating replacing of the original long-chain molecules of ligand shell of quantum dots with 1,2-ethanedithiol molecules. [ABSTRACT FROM AUTHOR]

The influence of meso-tetra(3-pyridyl)porphyrin (TPyP) on Förster resonance energy transfer (FRET) in aggregates of CdSe colloidal quantum dots (CQDs) has been studied. Upon the formation of such aggregates, interparticle FRET arises, leading to two effects. First, due to blinking, the observed luminescence quantum yield decreases. Second, due to inhomogeneous broadening of the optical spectra of CQDs, the luminescence band shifts to the long-wavelength side. The introduction of TPyP into the system leads to its adsorption on CQDs with multi-timescale kinetics. As a result, FRET from CQDs to TPyP arises, which effectively competes with FRET between CQDs themselves. As a result, the red shift arising due to aggregation of CQDs is significantly reduced. In this case, the dye adsorption has no effect on the position of the luminescence peak of the non-aggregated particles. [ABSTRACT FROM AUTHOR]

A new approach to the synthesis of lead sulfide colloidal quantum dots has been proposed, which uses a mixture of oleic acid and oleylamine. Colloidal quantum dots of PbS with a long-wavelength excitonic peak in the range from 1.7 to 2.05 μm have been obtained. The effects of temperature, reaction time, and the ratio of lead and sulfur precursors on the spectral characteristics of PbS quantum dots obtained have been studied. [ABSTRACT FROM AUTHOR]

A computer model of nonradiative electronic excitation energy transfer from nanoclusters of colloidal quantum dots of cadmium selenide to the meso-tetra(3-pyridyl)porphyrin molecule in hybrid nanostructures nanocluster–dye has been constructed and analyzed. The model uses the experimental luminescence and absorption spectra of quantum dots and the dye, takes into account heterogeneity of the properties of quantum dots in nanoclusters and the different location of the dye in the hybrid structure. It has been shown that, in the ideal case, due to such energy transfer, the intensity of the luminescent signal of the dye can be increased by five orders of magnitude. However, this value is significantly reduced due to nonluminescent particles, the presence of a protective ligand shell, a large size distribution of the particles, and the nonoptimal geometric structure of the hybrid system. [ABSTRACT FROM AUTHOR]

The electrophotophysical characteristics of laboratory samples of IR photodetectors obtained by dip coating of PbS colloidal quantum dots with the subsequent exchange of oleic acid molecules that compose their ligand shell by S2− ions have been studied. [ABSTRACT FROM AUTHOR]

Large-scale computer simulation of the luminescence spectra of nanoclusters of CdSe colloidal quantum dots has been carried out, taking into account Förster resonance electronic excitation energy transfer between the nanoparticles. Quantitative dependences of the energy transfer efficiency on various parameters of the nanocluster have been obtained and analyzed in two model cases: a cluster of the nanoparticles with a specified size distribution and a cluster of a mixture of the monodisperse nanoparticles of two sizes. It has been shown that the dispersion of particle size distribution, the thickness of the protective ligand shell, and the fraction of nonluminescent particles in the cluster largely influence the energy transfer efficiency. [ABSTRACT FROM AUTHOR]

The influence of 1,6-hexanedithiol as an additional short-chain stabilizing ligand on fluorescence blinking of semiconductor colloidal quantum dots InP@ZnS has been studied using the analysis of the fluorescence decay curves. The optimum proportion of 1,6-hexanedithiol in the mixture has been determined. The influence of the thickness of the ZnS shells and the diameter of the InP core has been also studied. Correlation of these dependences with the analogous dependences for the luminescence quantum yield is observed. [ABSTRACT FROM AUTHOR]

Abstract: Classical full-atomic molecular dynamics has been employed to study the effect of ligand environment on the dipole moments of colloidal quantum dots of cadmium selenide. Using trioctylphosphine oxide, hexadecylamine, and octadecylphosphonic acid as examples, it has been shown that the presence of uncompensated electrical charge at the polar group of a ligand molecule is the primary factor, while the distribution of point charges over the electrically neutral group is of secondary significance. Dipole-dipole interactions between CdSe nanoparticles make the greatest contribution upon the formation of dense layers, while, in solutions, this contribution is low as compared with the ordinary thermal motion. [ABSTRACT FROM AUTHOR]

Abstract: The influence of short-chain dithiols used in a mixture with 1-dodecanethiol to build up ZnS shells, on the spectral and luminescent properties of colloidal InP@ZnS quantum dots in the course of their liquid-phase colloidal synthesis has been studied. It has been shown that the use of dithiols permits targeted control of the luminescent properties of colloidal quantum dots. In this case, nanoparticles with a narrow emission band of ≈50 nm and a luminescence quantum yield up to 0.95 can be synthesized. The results obtained extend the capabilities of using InP@ZnS colloidal quantum dots in various functional materials. [ABSTRACT FROM AUTHOR]

The formation of hybrid nanostructures consisting of InP@ZnS colloidal quantum dots and mesotetra(3-pyridyl)porphyrin molecules adsorbed on the quantum dots has been studied. In such nanostructures, strong quenching of quantum dot luminescence and an increase in the emission intensity of porphyrin are observed due to nonradiative resonance energy transfer from colloidal quantum dots to porphyrin. [ABSTRACT FROM AUTHOR]

Classical molecular dynamics has been used to study the stabilization of colloidal quantum dots of CdSe with n-octadecylphosphonic acid molecules in combination with different auxiliary ligands, such as trioctylphosphine, trioctylphosphine oxide, and hexadecylamine. The effects of different ligands that may be formed due to interactions of n-octadecylphosphonic acid with CdO and Se in an initial mixture have been considered. It has been shown that, among these ligands, the stabilizing effect increases with a rise in the charge of a ligand per n-octadecyl chain. The role of the auxiliary ligands, e.g. octadecene that devoid of functional groups, has been studied. [ABSTRACT FROM AUTHOR]