TY - JOUR A1 - Frank, Maximilian A1 - Pflaum, Jens T1 - Tuning Electronic and Ionic Transport by Carbon–Based Additives in Polymer Electrolytes for Thermoelectric Applications JF - Advanced Functional Materials N2 - 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. KW - carbon nanotubes KW - thermoelectric generators KW - thermoelectric characterization KW - polymer electrolytes KW - impedance spectroscopy KW - electrochemistry Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-318908 SN - 1616-301X VL - 32 IS - 32 ER - TY - JOUR A1 - Kim, N. Y. A1 - Kusudo, K. A1 - Löffler, A. A1 - Höfling, S. A1 - Forchel, A. A1 - Yamamoto, Y. T1 - Exciton-polariton condensates near the Dirac point in a triangular lattice JF - New Journal of Physics N2 - Dirac particles, massless relativistic entities, obey linear energy dispersions and hold important implications in particle physics. The recent discovery of Dirac fermions in condensed matter systems including graphene and topological insulators has generated a great deal of interest in exploring the relativistic properties associated with Dirac physics in solid-state materials. In addition, there are stimulating research activities to engineer Dirac particles, elucidating their exotic physical properties in a controllable setting. One of the successful platforms is the ultracold atom-optical lattice system, whose dynamics can be manipulated and probed in a clean environment. A microcavity exciton-polariton-lattice system offers the advantage of forming high-orbital condensation in non-equilibrium conditions, which enables one to explore novel quantum orbital order in two dimensions. In this paper, we experimentally construct the band structures near Dirac points, the vertices of the first hexagonal Brillouin zone with exciton-polariton condensates trapped in a triangular lattice. Due to the finite spectral linewidth, the direct map of band structures at Dirac points is elusive; however, we identify the linear part above Dirac points and its associated velocity value is similar to ~0.9-2 x \(10^8 cm s^{-1}\), consistent with the theoretical estimate \(1 x 10^8 cm s^{-1}\) with a \(2 \mu m\) lattice constant. We envision that the exciton-polariton condensates in lattices would be a promising solid-state platform, where the system order parameter can be accessed in both real and momentum spaces. KW - Bose-Einstein condensation KW - carbon nanotubes KW - graphene KW - electron KW - dynamics KW - fermions KW - trap KW - gas Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-123103 SN - 1367-2630 VL - 15 IS - 035032 ER -