Highly uniform and low-loss passive silicon photonics devices using a 300mm CMOS platform

Using an advanced 300mm CMOS-platform, we report record-low and highly-uniform propagation loss: 0.45 +/- 0.12dB/cm for wires, and 2dB/cm for slot waveguides. For WDM devices, we demonstrate channel variation(3-sigma) within-wafer and within-device of 6.1nm and 1.2nm respectively

Enhanced luminescence properties of highly threaded conjugated polyelectrolytes with potassium counter-ions upon blending with poly(ethylene oxide)

The photophysics and electroluminescence (EL) of thin films of unthreaded and cyclodextrin-encapsulated poly(4,4’-diphenylenevinylene) (PDV) with potassium countercations, blended with poly(ethylene oxide) (PEO) are investigated as a function of the PEO concentration. We show that three main factors contribute to increasing the photoluminescence (PL) quantum efficiency as a result of suppressed intermolecular interactions, namely: the high degree of encapsulation of the polyrotaxanes, the relatively large countercation (e.g., compared to lithium), and the complexation of the rotaxanes with PEO. By facilitating cationic transport to the negative electrodes, PEO also leads to devices with enhanced electron injection and improved charge balance, whose operation therefore resembles that of “virtually unipolar” light-emitting electrochemical cells. This effect, together with the enhanced PL efficiency, leads to higher EL efficiency for both polyrotaxanes and unthreaded polymers, upon addition of the PEO. We show that the concurrent exploitation of the various strategies above lead to an overall EL efficiency that is approximately twice the value previously reported for Li-based PDV. A blueshift of the EL spectrum during the devices turn-on is also reported and analyzed in terms of interference and doping effects. 2010 American Institute of Physics. [doi:10.1063/1.3372616

Emission Color Trajectory and White Electroluminescence Through Supramolecular Control of Energy Transfer and Exciplex Formation in Binary Blends of Conjugated Polyrotaxanes

White electroluminescence and fine-tuning of the emission color from binary blends of a blue-emitting polymer and a green/yellow-emitting threaded molecular wire consisting of a conjugated polymer supramolecularly encapsulated by functionalized cyclodextrins are demonstrated. Encapsulation controls the minimum intermolecular distance on the nanoscale, resulting in suppressed energy-transfer between the blend constituents and reduced formation of interchain charge-transfer complexes. The use of a green-emitting polyrotaxane significantly improves the electrical properties with respect to blends of a blue electroluminescent polyrotaxane and leads to a significant reduction in the turn-on voltage required for achieving white electroluminescence (V ON = 3V), with only 20% by weight of the encapsulated material. Blends of a blue-emitting polymer and a green/yellow-emitting threaded molecular wire emit white luminescence due to control of the minimum intermolecular distance at the nanoscale, which results in suppressed energy transfer between the blend constituents and reduced formation of interchain charge-transfer complexes. Light-emitting diodes incorporating only 20% by weight of the encapsulated material display white electroluminescence with a turn-on voltage of just 3 V. Copyright © 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim

Enhanced luminescence properties of highly threaded conjugated polyelectrolytes with potassium counter-ions upon blending with poly(ethylene oxide)

The photophysics and electroluminescence (EL) of thin films of unthreaded and cyclodextrin-encapsulated poly(4, 4′ -diphenylenevinylene) (PDV) with potassium countercations, blended with poly(ethylene oxide) (PEO) are investigated as a function of the PEO concentration. We show that three main factors contribute to increasing the photoluminescence (PL) quantum efficiency as a result of suppressed intermolecular interactions, namely: the high degree of encapsulation of the polyrotaxanes, the relatively large countercation (e.g., compared to lithium), and the complexation of the rotaxanes with PEO. By facilitating cationic transport to the negative electrodes, PEO also leads to devices with enhanced electron injection and improved charge balance, whose operation therefore resembles that of "virtually unipolar" light-emitting electrochemical cells. This effect, together with the enhanced PL efficiency, leads to higher EL efficiency for both polyrotaxanes and unthreaded polymers, upon addition of the PEO. We show that the concurrent exploitation of the various strategies above lead to an overall EL efficiency that is approximately twice the value previously reported for Li-based PDV. A blueshift of the EL spectrum during the devices turn-on is also reported and analyzed in terms of interference and doping effects. © 2010 American Institute of Physics

Polyfluorene-based light-emitting diodes with an azide photocross-linked poly(3,4-ethylene dioxythiophene):(polystyrene sulfonic acid) hole-injecting layer

10.1063/1.2892685Applied Physics Letters9210-APPL

Highly polarized emission from oriented films incorporating water-soluble conjugated polymers in a polyvinyl alcohol matrix.

Highly oriented luminescent films are produced by stretching a 30-μm-thick polyvinyl alcohol matrix doped with water-soluble polyrotaxanes and their unthreaded analogues. Photoluminescence experiments reveal that over 95% of the emitted light is polarized along the orientation direction. A hybrid organic-inorganic light-emitting diode is built to investigate the possibility of using these films as polarizing filters for solid-state lighting and display technology. © 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim

White Electroluminescence by Supramolecular Control of Energy Transfer in Blends of Organic-Soluble Encapsulated Polyfluorenes

Here, it is demonstrated that energy transfer in a blend of semiconducting polymers can be strongly reduced by non-covalent encapsulation of one constituent, ensured by threading of the conjugated strands into functionalized cyclodextrins. Such macrocycles control the minimum intermolecular distance of chromophores with similar alignment, at the nanoscale, and therefore the relevant energy transfer rates, thus enabling fabrication of white-light-emitting diodes (CIE coordinates: x = 0.282, y = 0.336). In particular, white electroluminescence in a binary blend of a blueemitting, organic-soluble rotaxane based on a polyfluorene derivative and the green-emitting poly(9,9-dioctylfluorene-alt-benzotrtiadiazote (F8BT) is achieved. Morphological and structural analyses by atomic force microscopy, fluorescence mapping, μ-Raman, and fluorescence lifetime microscopy are used to complement optical and electroluminescence characterization, and to enable a deeper insight into the properties of the novel blend. © 2010 WILEY-VCH Verlag GmbH and Co. KGaA