Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Transient Spectroscopy of Glass-Embedded Perovskite Quantum Dots: Novel
  Structures in an Old Wrapping   Semiconductor doped glasses had been used by the research and engineering
communities as color filters or saturable absorbers well before it was realized
that their optical properties were defined by tiny specs of semiconductor
matter known presently as quantum dots (QDs). Nowadays, the preferred type of
QD samples are colloidal particles; however, there is still a number of
applications that would benefit from the availability of high-quality
glass-based QD samples. These applications include fiber optics, optically
pumped lasers and amplifiers, and luminescent solar concentrators. Here we
conduct optical studies of a new type of all-inorganic CsPbBr3 perovskite QDs
fabricated directly in glasses by high-temperature precipitation. These samples
are scattering free and exhibit excellent waveguiding properties. However, the
presently existing problem is their low room-temperature emission quantum
yields (QY) of only 1-2%. Here we investigate the reasons underlying the
limited QY by conducting transient photoluminescence (PL) and absorption
measurements across a range of temperatures from 20-300 K. We observe that the
low-temperature PL QY of these samples can be as high as ~25%. However, it
quickly drops with increasing temperature. Interestingly, experimental
observations cannot be explained in terms of a thermally activated nonradiative
rate but rather suggest the existence of two QD sub-ensembles of emissive and
completely nonemissive particles. The temperature-induced variation in the PL
efficiency is likely due to a structural transformation of the QD surfaces or
interior leading to formation of trapping sites or nonemissive phases resulting
in conversion of emissive QDs into nonemissive. Thus, future efforts on
improving emissivity of glass-based perovskite QD samples might focus on
approaches for extending the range of stability of the low-temperature up to
room temperature.

16
The categories of this paper are: stat
12
The categories of this paper are: nucl-th
6
The categories of this paper are: astro-ph
23
The categories of this paper are: solv-int
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The categories of this paper are: alg-geom
3
The categories of this paper are: physics
31
The categories of this paper are: ao-sci
30
The categories of this paper are: q-alg
33
The categories of this paper are: plasm-ph
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The categories of this paper are: q-fin
10
The categories of this paper are: q-bio
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The categories of this paper are: adap-org
2
The categories of this paper are: math
20
The categories of this paper are: acc-phys
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The categories of this paper are: nlin
5
The categories of this paper are: gr-qc