Emissive Polyelectrolytes As Interlayer for Color Tuning and Electron Injection in Solution-Processed Light-Emitting Devices

Herein we present a solution-processed hybrid device architecture combining organic light-emitting diodes (OLEDs) and light-emitting electrochemical cells (LECs) in a bilayer architecture. The LEC interlayer promotes the charge injection from an air-stable Ag cathode as well as permits the color tuning of the device emission. To this end, we used an alcohol-soluble anionic polyfluorene derivative, the properties of which were investigated by absorption and photoluminescence spectroscopy as well as by cyclic voltammetry. The bilayer device exhibited operating voltages ∼6 V and a color tuning of the emission spectrum dependent on the LEC interlayer thickness. The hybrid devices presented a color emission ranging from the yellow (<i>x</i> = 0.39, <i>y</i> = 0.47) toward the green region (<i>x</i> = 0.29, <i>y</i> = 0.4) of the Commission Internationale de I’Eclairage (CIE) 1931 chromaticity diagram

High-Performance Electron Injection Layers with a Wide Processing Window from an Amidoamine-Functionalized Polyfluorene

In this work, we present organic light-emitting diodes (OLEDs) utilizing a novel amidoamine-functionalized polyfluorene (PFCON-C) as an electron injection layer (EIL). PFCON-C consists of a polyfluorene backbone to which multiple tertiary amine side chains are connected via an amide group. The influence of molecular characteristics on electronic performance and morphological properties was tested and compared to that of the widely used, literature known amino-functionalized polyfluorene (PFN) and polyethylenimine (PEI). PFCON-C reduces the turn-on voltage (<i>V</i>_ON) of poly­(<i>p</i>-phenylene vinylene) (PPV)-based OLEDs from ∼5 to ∼3 V and increases the maximum power efficiency from <2 to >5 lm W^–1 compared to that of PFN. As a result of its semiconducting backbone, PFCON-C is significantly less sensitive to the processing parameters than PEI, and comparable power efficiencies are achieved for devices where thicknesses of PFCON-C are between 15 and 35 nm. Atomic force microscopy (AFM) measurements indicate that the presence of nonpolar side chains in the EIL material is important for its film-forming behavior, while Kelvin probe measurements suggest that the amount of amine groups in the side chains influences the work-function shift induced by the EIL material. These results are used to suggest strategies for the design of polymeric electron injection layers

Hemodynamic changes related to induction of aortic insufficiency and cardiac preload changes (mixed model).

<p>Hemodynamic changes related to induction of aortic insufficiency and cardiac preload changes (mixed model).</p

Porcine model for experimental aortic valve insufficiency.

<p>(A) A Judkins catheter was used as a guiding catheter to deliver a Dormia basket, (B) The Judkins catheter was introduced via an introducer sheath in the carotid artery and advanced through the brachiocephalic trunk into the ascending aorta (AscAo), (C) A compressed Dormia basket was delivered via the Judkins catheter through the aortic valve (AoV) in the left ventricle (LV). Subsequently the expanded Dormia basket was retracted in the aortic valve annulus, (D) Targeted tip position for the Dormia basket to induce substantial aortic valve regurgitation verified by epicardial echocardiography (E).</p

Four-quadrant plots.

<p>Trending ability of cardiac output (CO) derived from transcardiopulmonary thermodilution (CO_TCPTP) compaired with CO_PAC (reference method) illustrated by four-quadrant plots. The ability to trend CO changes induced by preload changes was assessed during baseline conditions (left: competent aortic valve) and after induction of aortic valve insufficiency (right). Changes in cardiac preload were induced by fluid unloading (black dots: withdrawal of 20 ml kg^-1 blood) and subsequent fluid loading (white dots: retransfusion of the shed blood and additional infusion of 20 ml kg^-1 hydroxyethyl starch). The concordance analysis gives a concordance rate of 95.8% during both conditions, baseline and aortic valve insufficiency. An exclusion zone of 0.5 l min^-1 (grey area in the center) was applied.</p