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Organic dyes offer unique properties for their application as room temperature single photon emitters. By means of photon‐correlation, the emission characteristics of macrocyclic para‐xylylene linked perylene bisimide (PBI) trimers and tetramers dispersed in polymethyl methacrylate matrices are analyzed. The optical data indicate that, despite of the strong emission enhancement of PBI trimers and tetramers according to their larger number of chromophores, the photon‐correlation statistics still obeys that of single photon emitters. Moreover, driving PBI trimers and tetramers at higher excitation powers, saturated emission behavior for monomers is found while macrocycle emission is still far‐off saturation but shows enhanced fluctuations. This observation is attributed to fast singlet–singlet annihilation, i.e., faster than the radiative lifetime of the excited S1 state, and the enlarged number of conformational arrangements of multichromophores in the polymeric host. Finally, embedding trimeric PBI macrocycles in active organic light‐emitting diode matrices, electrically driven bright fluorescence together with an indication for antibunching at room temperature can be detected. This, so far, has only been observed for phosphorescent emitters that feature much longer lifetimes of the excited states and, thus, smaller radiative recombination rates. The results are discussed in the context of possible effects on the g(2) behavior of molecular emitters.
Thermoelectric materials utilizing ionic transport open-up entirely new possibilities for the recuperation of waste heat. Remarkably, solid state electrolytes which have entered the focus of battery research in recent years turn-out to be promising candidates also for ionic thermoelectrics. Here, the dynamics of ionic transport and thermoelectric properties of a methacrylate based polymer blend in combination with a lithium salt is analyzed. Impedance spectroscopy data indicates the presence of just one transport mechanism irrespective of lithium salt concentration. In contrast, the temperature dependent ionic conductivity increases with salt concentration and can be ascribed to a Vogel–Fulcher–Tammann (VFT) behavior. The obtained Seebeck coefficients of 2 mV K\(^{−1}\) allow for high power outputs while the polymer matrix maintains the temperature gradient by its low thermal conductivity. Adding multi-walled carbon nanotubes to the polymer matrix allows for variation of the Seebeck coefficient as well as the ionic and electronic conductivities. As a result, a transition between a high temperature VFT regime and a low temperature Arrhenius regime appears at a critical temperature, T\(_{c}\), shifting upon addition of salt. The observed polarity change in Seebeck voltage at T\(_{c}\) suggests a new mode of thermoelectric operation, which is demonstrated by a proof-of-concept mixed electronic-ionic-thermoelectric generator.