Browsing by Subject "Photoluminescence intensities"

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Open Access
Facile route to produce spherical and highly luminescent Tb3+doped Y2O3 nanophosphors
(Elsevier, 2017) Kumar, D.; Sharma, M.; Haranath, D.; Pandey, O. P.
Terbium doped yttrium oxide (Y2O3:Tb3+) nanophosphor has been synthesized via a facial yet modified co-precipitation method. To get maximum luminescence output from Y2O3:Tb3+nanophosphors, surfactants namely, Cetyl trimethylammonium bromide (CTAB) and Trioctylphosphine oxide (TOPO) were added during synthesis. Further, it has been observed that combined addition of surfactant (CTABï¿½+ï¿½TOPO) at the time of synthesis has resulted in nearly spherical morphology of the nanophosphor. Furthermore, these optimized material are observed to have enhanced integrated photoluminescence (PL) intensity of ∼23% as compared to the one synthesized without the addition of any surfactant. The results are further supported by detailed structural and optical studies. Optimum use of surfactants during synthesis shows for the first time that both nano-sized distribution and high crystallinity can be achieved simultaneously which has resulted in bright green emission in Tb3+doped Y2O3nanophosphors.
Open Access
Temperature-dependent emission kinetics of colloidal semiconductor nanoplatelets strongly modified by stacking
(American Chemical Society, 2016) Erdem, O.; Olutas M.; Guzelturk, B.; Kelestemur Y.; Demir, Hilmi Volkan
We systematically studied temperature-dependent emission kinetics in solid films of solution-processed CdSe nanoplatelets (NPLs) that are either intentionally stacked or nonstacked. We observed that the steady-state photoluminescence (PL) intensity of nonstacked NPLs considerably increases with decreasing temperature, whereas there is only a slight increase in stacked NPLs. Furthermore, PL decay time of the stacked NPL ensemble is comparatively much shorter than that of the nonstacked NPLs, and this result is consistent at all temperatures. To account for these observations, we developed a probabilistic model that describes excitonic processes in a stack using Markov chains, and we found excellent agreement between the model and experimental results. These findings develop the insight that the competition between the radiative channels and energy transfer-assisted hole trapping leads to weakly temperature-dependent PL intensity in the case of the stacked NPL ensembles as compared to the nonstacked NPLs lacking strong energy transfer. This study shows that it is essential to account for the effect of NPL stacking to understand their resulting PL emission properties.