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Porous nanostructured photonic materials in the shape of periodic multilayers have demonstrated their potential in different fields ranging from photovoltaics[1] to sensing,[2] representing an ideal platform for flexible devices. When applications dealing with light absorption or emission are considered, knowledge on how the local density of states (LDOS) is distributed within them is mandatory[3] in order to realize a judicious design which maximizes light matter interaction.
Using a combination of spin and dip-casting we report a detail study of how dye doped polystyrene nanospheres constitute an effective LDOS probe to study its distribution within nanostructured photonic media.[4] This full solution process approach allows to cover large areas keeping the photonics properties. Nanospheres with a diameter of 25 nm are incorporated in nanostructured multilayers (Fig. 1a).. This allows to place them at several positions of the structured sample (Fig. 1b). A combined use of photoluminescence spectroscopy and time resolved measurements are used to optically characterize the samples. While the former shows how depending on the probe position its PL intensity can be enhanced or suppressed, the latter allows to probe the LDOS changes within the sample, monitored via changes in its lifetime. We demonstrate how information on the local photonic environment can be retrieved with a spatial resolution of 25 nm (provided by the probe size) and relative changes in the decay rates as small as ca. 1% (Fig. 1c), evidencing the possibility of exerting a fine deterministic control on the photonic surroundings of an emitter.
References
[1] C. López-López, S. Colodrero, M. E. Calvo and H. Míguez, Energy Environ. Sci., 23, 2805 (2013).
[2] A. Jiménez-Solano, C. López-López, O. Sánchez-Sobrado, J. M. Luque, M. E. Calvo, C. Fernández-López, A. Sánchez-Iglesias, L. M. Liz-Marzán and H. Míguez. Langmuir, 28, 9161 (2012).
[3] N. Danz, R. Waldhäusl, A. Bräuer and R. Kowarschik, J. Opt. Soc. Am. B, 19, 412 (2010).
[4] A. Jiménez-Solano, J. F. Galisteo-López and H. Míguez, Small, 11, 2727 (2015).
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