EMRS Spring Meeting 2014

Aktivitet: Foredrag og mundtlige bidragKonferenceoplæg


Periodic deposition of para-hexaphenyl (p6P) crystalline nanofibers and -sexithiophene (6T) monolayers via hot wall epitaxy enables color tuning within the red, green, and blue spectral range by varying the relative thicknesses of the constituent materials [1, 2]. Illumination of the multilayered sample with UV light (3.8 eV photon energy) causes p6P fluorescence, while the 6T monolayers emit light due to sensitization via the excited p6P [2]. Illumination with blue light (2.5 eV photon energy), which is below the optical gap of p6P, excites photoluminescence (PL) only from the 6T monolayer [3]. Here, we probe the energy transfer and light emission characteristics by temperature dependent PL spectroscopy using either 3.8 eV or 2.5 eV photons for stimulating the p6P or 6T layers, respectively. While the p6P quantum yield decreases by an order of magnitude between 6 K and 293 K, the 6T monolayer emission exhibits much weaker temperature dependence. This is attributed to the fact that crystalline p6P layers are H aggregates while 6T monolayers have a radically different aggregation state (most presumably J aggregates). The ratio between emission intensity of the sensitized and directly excited 6T monolayer increases by around 40% when increasing the temperature from 6 K to 293 K due to enhanced energy transfer from p6P to the 6T monolayer. 1 C. Simbrunner et al. ACS Nano 4, 6244 (2010) 2 C. Simbrunner et al. ACS Nano 6, 4629 (2012) 3 F. Quochi et al. Adv. Opt. Mat. 1, 117 (2013)
Periode26. maj 201430. maj 2014
BegivenhedstitelEMRS Spring Meeting 2014
PlaceringLille, Frankrig