Optical monitoring of quantum dots in NaCl:Pb crystal

Journal of Crystal Growth, 1993

Purification and crystal growth of PhCI and congruc it l~melting ternars alkal lead chlorides. KPh~CI Rb PbCl Rhl'b ( 1 and CsPhCI~, will he described in the present paper. Source materials were purified by the chlorination of molten chlorides ss jib gaseous mixture of chlorinating agents in combination with a suhscq lien! zone-melting. The efficiency 01 t Ii is method is con) irmcd by chemical analysis before and alter purification and by the behaviour of the melts. Large single crystals of l'b(l KE'b('I RhPb~C'l and CsPhCI 2(1 nim in diameter and 50-61) mni long, were grow ii by the ltridgman method. Their qua I its was checked hy the optical absorption and elastic light scattering measureme nts,

1993

Chemphyschem : a European journal of chemical physics and physical chemistry, 2015

Colloidal quantum dots (CQDs) can be used in conjunction with organic charge-transporting layers to produce light-emitting diodes, solar cells and other devices. The efficacy of CQDs in these applications is reduced by the non-radiative recombination associated with surface traps. Here we investigate the effect on the recombination dynamics in CdTe CQDs of the passivation of these surface traps by chloride ions. Radiative recombination dominates in these passivated CQDs, with the radiative lifetime scaling linearly with CQD volume over τr =20-55 ns. Before chloride passivation or after exposure to air, two non-radiative components are also observed in the recombination transients, with sample-dependent lifetimes typically of less than 1 ns and a few ns. The non-radiative dynamics can be explained by Auger-mediated trapping of holes and the lifetimes of this process calculated by an atomistic model are in agreement with experimental values if assuming surface oxidation of the CQDs.

The Journal of Chemical Physics, 2019

The absorption cross section of lead halide perovskite nanocrystals is important for understanding their photophysical properties, especially those depending on the density of photoexcited charge carriers. Despite its importance, there are large discrepancies among the reported absorption cross section values determined employing different methods. Here, we measured the absorption cross section of CsPbBr3 quantum dots (QDs) of varying sizes using elemental analysis and transient absorption (TA) saturation methods and compared with the previously reported values determined from elemental analysis and transient photoluminescence (PL) saturation methods. A careful comparison indicates that the reliable absorption cross section of lead halide perovskite QDs is obtained from both elemental analysis and TA saturation methods, while many previously reported values determined from the PL saturation method underestimate the absorption cross section.

Crystal Research and Technology, 1995

Single crystals of pure and doped lead(I1)chloride and lead(I1)bromide were grown by gel technique employing a modified two-stage chemical reaction. Methods to minimise the predomination of needle morphology during the growth of these crystals have been investigated and the results are discussed. The grown crystals were characterised by optical transmission spectrum. Undoped and monovalent cation (K', Na+, Cu', Ag' and Hg') doped crystals of PbCI, and PbBr, were subjected to d.c. electrical conductivity studies. Using the log oT versus Tplot, the activation energies for the migration of anion vacancies in lead(I1)halides are calculated. They are found to be less for the doped crystals than those of undoped ones.

1985

Inorganic Materials, 2006

We have demonstrated for the first time the possibility of preparing high purity and praseody mium and dysprosium doped solid solutions based on lead halides and alkali metals: Rb 1 -x Cs x Pb 2 Cl 5 , Rb 1 -x Cs x Pb 2 Br 5 , Rb 1 -x K x Pb 2 Cl 5 , and RbPb 2 Cl 5 -y Br y . According to X ray diffraction data, Rb 1 ⎯ x Cs x Pb 2 Cl 5 and Rb 1 -x Cs x Pb 2 Br 5 crystals in the solid solution range are isostructural with the constitu ent double salts RbPb 2 Cl 5 and RbPb 2 Br 5 , respectively. The double salt Rb 0.5 K 0.5 Pb 2 Cl 5 is isostructural with KPb 2 Cl 5 , and the double mixed salt RbPb 2 Cl 2.5 Br 2.5 is isostructural with RbPb 2 Br 5 . The Pr 3+ and Dy 3+ con centrations in crystals of the solid solutions and mixed salts were determined by inductively coupled plasma mass spectrometry (ICP MS). In the Rb 1 -x (Cs, K) x Pb 2 Hal 5 (Hal = Cl, Br) solid solutions, the dopants were observed to be nonuniformly distributed over the host. According to ICP MS analysis data and absorption spectra, the Pr 3+ and Dy 3+ concentrations in the RbPbCl 2.5 Br 2.5 crystals were higher than those in RbPb 2 Br 5 .

Industrial & Engineering Chemistry Research, 2016

Supporting Information The elemental analyses and optical responses of CdSe (4:3:1) QDs treated with different amount of Pb precursors, optical responses of purified and unpurified CdSe (4:3:1) QDs after Pb treatment, and the X-ray diffraction patterns of CdSe (4:1:1) versus CdSe (4:1:1)/1Pb were summarized as follows.

Physical Chemistry Chemical Physics, 2014

Conjugated polymer-semiconductor quantum dot (QD) composites are attracting increasing attention due to the complementary properties of the two classes of materials. We report a convenient method for in situ formation of QDs, and explore the conditions required for light emission of nanocomposite blends. In particular we explore the properties of nanocomposites of the blue emitting polymer poly[9,9-bis(3,5-di-tert-butylphenyl)-9H-fluorene] together with cadmium sulphide (CdS) and cadmium selenide (CdSe) precursors. We show the formation of emissive quantum dots of CdSe from thermally decomposed precursor. The dots are formed inside the polymer matrix and have a photoluminescence quantum yield of 7.5%. Our results show the importance of appropriate energy level alignment, and are relevant to the application of organic-inorganic systems in optoelectronic devices.

Optical Materials, 2013

This paper reports on the growth of pure and Nd 3+ , Pr 3+ , Yb 3+ , and Dy 3+ doped rubidium lead chloride (RbPb 2 Cl 5 ) crystals by the atmosphere-controlled micro-pulling-down method. Structural and composition measurements are reported, further completed by the absorption, radio-and photoluminescence spectra and decay measurements on the prepared single crystals. Potential of these materials and preparation method for the application in the infrared solid state laser field are discussed.