Luminescent properties and electronic structure of conjugated polymer-dielectric nanocrystal composites

We report results of experimental investigations of the luminescent properties of two different conjugated polymers in which we embedded nanocrystals of Al2O3,Al2O3, Y2O3,Y2O3,ZnO, and SnSbO. The dielectricnanocrystals result in a blueshifting and broadening of luminescence spectra of poly(p-phenylenepoly(p-phenylene vinylene) with a simultaneous disappearance of its vibronic structure. The same nanocrystals in a poly[2-(6-cyano-6′-methylheptyloxy)-1,4-phenylene]poly[2-(6-cyano-6′-methylheptyloxy)-1,4-phenylene] matrix cause redshifting and spectral broadening. These observations are explained by referring to a model that accounts for the change in the polarization component of the carrier and exciton energy in the vicinity of inclusions

Luminescence from processible quantum dot-polymer light emitters 1100–1600 nm: Tailoring spectral width and shape

Electroluminescent devices combining two families of PbScolloidalquantum dots to achieve spectrally tailored two-color emission are reported. Depending on device structure selected—the use of two separated layers versus a mixture of nanocrystals—the structures demonstrated light emission either in two infrared frequency peaks corresponding to the spectral region 1.1–1.6 μm or in a wide band spanning this same spectral region. Separated-layer devices exhibit wide tunability in the relative intensity of the two peaks by varying excitation conditions. Replacing oleate with octodecylamine ligands increases the internal electroluminescence efficiency to 3.1%

Size-tunable infrared (1000–1600 nm) electroluminescence from PbS quantum-dot nanocrystals in a semiconducting polymer

Nanocomposites consisting of PbSnanocrystals in a conjugated polymer matrix were fabricated. We report results of photo- and electroluminescence across the range of 1000 to 1600 nm with tunability obtained via the quantum-size effect. The intensity of electroluminescence reached values corresponding to an internal quantum efficiency up to 1.2%. We discuss the impact of using different-length capping ligands on the transfer of excitations from polymer matrix to nanocrystals

Scalable Cost/Performance Analysis for Thermoelectric Waste Heat Recovery Systems

We study the cost/efficiency trade-offs for different values and identify applications in which low-cost organic thermoelectric (TE) materials such as polymers with embedded nanoparticles or nanowires could have a big impact. In a TE generator, in addition to the TE material, there needs to be a water- or air-cooled heat sink in order to create a temperature gradient. The costs of the material in the TE module and the heat sink need to be co-optimized. We used our recently developed analytic model which describes the maximum power output for various conditions. The optimum design allows us to find the minimum material mass used in the TE module and in the heat sink. This yields the power per material cost (W/$) and the power per unit mass (kg/W). We compared organic and inorganic TE materials as an interesting example based on this scalable analytic model. The results suggest that polymers or other low-cost lower-efficiency TE materials have the greatest potential for lightweight remote power applications for sensors in conjunction with passive heat sinks