Kristen Tandy

Simultaneous enhancement of brightness, efficiency, and switching in RGB organic light emitting transistors.

An innovative design strategy for light emitting field effect transistors (LEFETs) to harvest higher luminance and switching is presented. The strategy uses a non-planar electrode geometry in tri-layer LEFETs for simultaneous enhancement of the key parameters of quantum efficiency, brightness, switching, and mobility across the RGB color gamut.

Channel II photocurrent quantification in narrow optical gap polymer-fullerene solar cells with complimentary acceptor absorption

Most charge generation studies on organic solar cells focus on the conventional mode of photocurrent generation derived from light absorption in the electron donor component (so called channel I). In contrast, relatively little attention has been paid to the alternate generation pathway: light absorption in the electron acceptor followed by photo-induced hole transfer (channel II). By using the narrow optical gap polymer poly(3,6-dithieno[3,2-b]thiophen-2-yl)-2,5-bis(2-octyldodecyl)-pyrrolo-[3,4-c]pyrrole-1,4-dione-5′,5″-diyl-alt-4,8-bis(dodecyloxy)benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl with two complimentary fullerene absorbers; phenyl-C61-butyric acid methyl ester, and phenyl-C71-butyric acid methyl ester (70-PCBM), we have been able to quantify the photocurrent generated each of the mechanisms and find a significant fraction (>30%), which is derived in particular from 70-PCBM light absorption.

Using a birefringent probe particle in variable polarisation optical tweezers to probe properties of biological materials.

Probe particles held in force measuring optical tweezers (OT) are being widely used to probe biological fluids, membranes, and living cells. In some cases, the properties of a discrete molecule or microstructure to which the probe is attached are probed [1]. In other cases, as here, it is the viscoelastic properties of the material surrounding the probe which are of interest. These can be deduced from measurements of the response of the probe to a known applied force [2]. Alternatively, measurements of Brownian motion of a trapped particle can give information on the surrounding material [3].