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 blue‐emitting, organic‐soluble rotaxane based on a polyfluorene derivative and the green‐emitting poly(9,9‐dioctylfluorene‐alt‐benzothiadiazole (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.

We report the use of blends composed of poly(9,9′-dioctylfluorene-alt-benzothiadiazole), F8BT, and a polymeric ionic liquid (PIL), poly(vinyl-ethylimidazolium bistrifluoromethanesulfonimide), as the active layer in light-emitting electrochemical cells (LECs) with the simple indium-tin-oxide/active-layer/Al configuration. The PIL provides both the ionic charge and the transport channel necessary for the devices to operate as LECs resulting in reduction of charge injection barriers at the electrode/active-layer interfaces. We find that the performance of devices using PIL:F8BT blends improved with respect to pure F8BT with maximum luminance increasing from 10–20 cd/m2 for pure F8BT to 2000–4000 cd/m2 for blends. Turn-on voltages were also reduced from above 7 V down to around 3.6–4 V. The maximum external quantum efficiency was increased from 10−3%–10−4% to values higher than 0.1%.

Abstract: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-σ) within-wafer and within-device of 6.1nm and 1.2nm respectively.