36 research outputs found
Photophysics of Two-Dimensional Perovskites—Learning from Metal Halide Substitution
Whereas their photophysics exhibits an intricate interplay of carriers with
the lattice, most reports have so far relied on single compound studies. With
the exception of variations of the organic spacer cations, the effect of
constituent substitution on the photophysics and the nature of emitting
species, in particular, has remained largely under-explored. Here
PEAPbBr, PEAPbI, and PEASnI are studied through a
variety of optical spectroscopy techniques to reveal a complex set of excitonic
transitions at low temperature. We attribute the emergence of weak high energy
features to a vibronic progression breaking Kasha's rule and highlight that the
responsible phonons cannot be accessed through simple Raman spectroscopy.
Bright peaks at lower energy are due to two distinct excitons, of which the
upper is a convolution of a bright exciton and a localised state, whereas the
lower is attributed to shallow defects. Our study offers deeper insights into
the photophysics of two-dimensional perovskites through compositional
substitution and highlights critical limits to the communities' current
understanding of the photophysics of these compounds
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Development of nanoemulsions for topical delivery of vitamin K1
Vitamin K1 (VK1) is a natural and lipophilic compound currently used in dermatological formulations. In this work, nanoemulsions containing VK1 have been proposed to overcome some issues associated to semisolid VK1-incorporating formulations. The study has been focused on the design of a lipid-free aqueous formulation, easy to prepare and with low cost of production. Thus, a simply protocol, using a low-energy method, has been used to spontaneously form the nanoemulsions. The nanoemulsion composition has been optimized to improve its physical stability during storage in different conditions. Then, the possibility to administer VK1-containing nanoemulsions by nebulization without significant alteration of the formulation was tested. Moreover, the VK1 accumulation into the skin layers have been evaluated through permeation experiments on Franz cells, ATR-FITR analysis, confocal laser scanning microscopy (CLSM) observations, and high performance liquid chromatography (HPLC) analysis. The study demonstrated that NEs represent an interesting option for the commercial development of an aqueous spray formulation for the topical delivery of VK1