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Se2− color centers and CdSe/Cd1−xZnxSe quantum dots (QDs) were formed in silicate glasses, respectively, by carefully adjusting the content of Al2O3. The absorption coefficient and broad visible emission at 400‐700 nm of Se2− color centers increased firstly and then decreased upon increasing concentration of Al2O3 from 0 to 5 mol. %. With 2 mol. % Al2O3 adding, the band edge emission centered at 497 nm from CdSe QDs in glasses was observed after heat treatment. Raman spectra and TEM characterization confirmed the formation of CdSe/Cd1−xZnxSe QDs. The small amount addition of Al2O3 had a significant effect on the formation of Se2− color centers and precipitation of CdSe/Cd1−xZnxSe QDs in glasses due to its complicated effect on the network structure and optical basicity of the glasses. [ABSTRACT FROM AUTHOR]

Abstract: In order to alleviate the effect of the surface defects on the emission properties of quantum dots, copper ions‐doped ZnSe quantum dots (QDs) in the glasses are prepared using melt‐quenching and subsequent thermal annealing methods. For glasses without copper doping, tunable band‐edge emission from ZnSe QDs is achieved. For glasses with copper doping, efficient energy transfer from ZnSe QDs to copper ions is observed, and efficient broad band emission from copper ions is realized at the expense of the band‐edge emission of ZnSe QDs. Absorption spectra, size‐dependent broad‐band emission spectra and electron spin resonance spectra show the cupric ions are doped into the ZnSe QDs. Results reported here shows that doping of transition‐metal ions into semiconductor QDs in glasses is promising for development of high efficient luminescent glasses. [ABSTRACT FROM AUTHOR]

Lead selenide (PbSe) quantum dots (QDs) doped with Sr 2 + were precipitated in silicate glasses. The absorption and photoluminescence (PL) bands of the glasses blue-shifted as SrO concentration increased. These changes resulted mainly because Sr incorporation increased the band gap of PbSe nanocrystals. After heat treatment at 520 °C for 10 h, mean QD diameters were similar before and after the addition of SrO: ~ 7.2 nm with 0% SrO and ~ 6.9 nm with 10 mol% SrO. However, these two glasses show the absorption bands at 1743 nm and 1246 nm, and PL bands at 1803 and 1370 nm, respectively. These large shifts are due to the increase in the band gap through the formation of Pb 1 − x Sr x Se mixed-type QDs. One typical chemical composition of QDs formed in a glass with 10 mol% SrO after heat treatment at 520 °C for 10 h is Pb 0.89 Sr 0.11 Se with a band gap of ~ 0.58 eV. [ABSTRACT FROM AUTHOR]

Infrared photoluminescence (PL) properties of Sn-modified PbSe quantum dots (QDs) in silicate glass were investigated. The QDs' sizes were controlled by changing the heat treatment temperatures. The longest absorption peak from Sn-modified PbSe QDs was centered at 2590 nm, and the PL band extended to 2650 nm. X-ray diffraction peaks indicated that the PbSe QDs formed in the glass matrix although low Sn content resulted in no obvious difference between PbSe QDs and Sn-modified PbSe QDs. Sn was found in QDs that proves the incorporation of Sn into PbSe QDs. The proposed composition of the Sn-modified PbSe QDs was Pb 0.92 Sn 0.08 Se with a band gap of ~ 0.13 eV; the small amount of Sn changed the energy structure of QDs, narrowed the band-gap, and increased the PL emission wavelength. [ABSTRACT FROM AUTHOR]

Size-dependent Stokes shift of PbS quantum dots (QDs) formed in the glasses was investigated. PbS QDs with diameters of 3.5 nm to 13.3 nm were precipitated in silicate glasses with different S/Pb ratios using the conventional thermal treatment method. Absorption and photoluminescence (PL) of PbS QDs were tuned from ~0.9 µm (1.38 eV) to ~2.3 µm (0.54 eV) by adjusting the diameters of PbS QDs from 3.5 nm to 13.3 nm. PL energies of QDs exhibited linear dependence on the absorption energies with a slope of 0.484 for PbS QDs with band gap energies larger than 0.98 eV, and the maximum Stokes shift was found to be 206.2 meV for 3.5 nm-sized PbS QDs. For large PbS QDs with band gap energies smaller than 0.98 eV, Stokes shift was found to be ~20 meV or smaller. The size-dependent Stokes shift indicated that surface defects made the main contribution and relative energy positions of these surface defects were strongly dependent on the size of PbS QDs. [ABSTRACT FROM AUTHOR]

The formation mechanism of Cd–S–Se quantum dots (QDs) with a CdS/CdSe core–shell structure within a silicate glass system was investigated by monitoring the change in the first excitonic absorption peak of CdSe, CdS, and Cd–S–Se QDs as a function of the heat‐treatment (HT) duration. When a silicate glass containing QD formation components for CdSe or CdS single‐phased QDs was heat‐treated, CdSe QDs grew via Ostwald ripening, whereas CdS QDs hardly formed within the given silicate glass matrix. When the glass, including CdO, ZnSe, and ZnS, was utilized for the synthesis of Cd–S–Se QDs within the glass matrix, Cd–S–Se QDs were successfully formed and exhibited similar growth behavior to CdSe QDs during the initial stage of HT. The structural changes in the QD‐embedded glasses during HT were also monitored by Raman spectroscopy and discussed, and a possible formation mechanism of CdSe/CdS core–shell‐structured QDs within silicate glasses is suggested. [ABSTRACT FROM AUTHOR]

Photoluminescence (PL) properties of PbSe and Sr2+‐doped PbSe quantum dots (QDs) doped in silicate glasses were investigated by changing the excited laser wavelength and intensity. When BaO was replaced by SrO, the Sr2+‐doped PbSe QDs formed and showed large blue‐shifts in both absorption and PL bands compared to the PbSe QDs. It is attributed to the increasing in band gap resulted by the incorporation of Sr2+ ions into PbSe QDs. These two kinds of QDs were excited by the laser with the wavelengths of 1319 and 1532 nm. When rising the pumping intensity up to 1000 mW, the PL intensity from Sr2+‐doped PbSe QDs monotonically increased, while, the PL intensity from PbSe QDs reached maximum at pumping intensity at ~200 mW (λex = 1319 nm) and ~300 mW (λex = 1532 nm). The good resistance to photodarkening of Sr2+‐doped PbSe QDs is indicated passivation effect on the surface defects from Sr2+ ions doping. For Sr2+‐doped PbSe QDs the anti‐Stokes photoluminescence (ASPL) were observed when using both 1319 and 1532 nm excitation. The integrated intensity of the ASPL is linear with the excitation intensity, which indicates that the ASPL belongs to the phonon‐assisted one‐photon process. And the ASPL intensity as a function of excitation intensity shows a size dependence of the QDs. [ABSTRACT FROM AUTHOR]

Lead selenide quantum dots (QDs) were precipitated in germanosilicate glasses to investigate the effect of GeO 2 content on the precipitation and optical properties. The absorption and photoluminescence (PL) bands red-shifted strongly as GeO 2 concentration increased. After heat-treatment at 470 °C for 10 h, the first excitonic absorption bands red-shifted from 801 nm to 2593 nm as GeO 2 content increased from 0 to 40 mol%, and thus PL at 2619 nm was achieved. The corresponding average QD diameters were 2.48–12.54 nm. The precipitation of large PbSe QDs resulted from the enhancement of diffusion with the increase of GeO 2 concentration, and is the main reason for these red-shifts. [ABSTRACT FROM AUTHOR]

Embedding CdTe QDs into glass can improve the thermal and chemical stability of QDs, which facilitates their wide and endurable applications. However, the small tunable spectral range of photoluminescence, low quantum efficiency, and large full width at half maximum limit their wide applications. In this work, effect of introduction of CaO into glass matrix on the formation and optical properties of CdTe QDs is investigated. High concentration of CaO in glasses increases the solubility of Te in glasses, and consequently hinders the precipitation of CdTe QDs in glasses. By adjusting the heat-treatment temperature, average diameters of CdTe QDs are tuned in the range of 2.5–9.0 nm and their photoluminescence bands are tuned from 550 to 800 nm. More importantly, the absolute photoluminescence quantum yield is boosted up to 41.9 %. Results reported in this work indicate that CdTe quantum dots embedded in glasses are promising for applications in light-emitting devices. • High CaO concentration promote the dissolution of Te in the glass. • Photoluminescence of CdTe QDs doped glass is tuned from 550 nm to 800 nm. • PLQY of CdTe QDs doped glasses reaches 41.9 %. [ABSTRACT FROM AUTHOR]

• Ternary Pb 1−x Sr x Se quantum dots were prepared in the silicate glass. • Pb2+ concentration determine the density of Pb 1−x Sr x Se QDs in glassy matrix. • The higher Se/Pb ratio facilitates the formation of large-size quantum dots. Lead selenide quantum dots (QDs) were precipitated in silicate glasses with different contents of SrO. As the concentration of SrO increased from 0 to 10 mol%, the absorption peaks of the glasses with the heat treatment at 520 °C for 10 h blue-shifted from 1535 nm to 947 nm, and their photoluminescence (PL) peaks from 1578 nm to 1184 nm. The blue-shifts resulted from the incorporation of Sr2+ ions into PbSe crystal lattice, which leads to the increase of the bandgap of PbSe QDs. Meanwhile, the optical properties of Sr2+-doped PbSe QDs were investigated by changing the precursor concentrations of Pb and Se. It is found that the concentration of Sr2+-doped PbSe QDs in the glassy matrix is mainly determined by the contents of the Pb precursor. To form larger size QDs requires higher oversaturation of Se to Pb elements, which promoted the further growth of QDs. [ABSTRACT FROM AUTHOR]