Daniel A Poulsen

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Precise control of the spatial organization of nanoscopic building blocks, such as nanoparticles, over multiple length scales is a bottleneck in the 'bottom-up' generation of technologically important materials. Only a few approaches have been shown to achieve nanoparticle assemblies without surface modification. We demonstrate a simple yet versatile(More)
The use of cross-linked polymer nanoparticles was explored to achieve site isolation of different emitters within a single emissive layer in an electroluminescent device. Encapsulation of the iridium emitters within the polymer nanoparticles led to the desired effect with minimal energy transfer from high bandgap chromophores to lower bandgap ones. The(More)
Photomechanical switching (photoisomerization) of molecules at a surface is found to strongly depend on molecule-molecule interactions and molecule-surface orientation. Scanning tunneling microscopy was used to image photoswitching behavior in the single-molecule limit of tetra-tert-butyl-azobenzene molecules adsorbed onto Au(111) at 30 K. Photoswitching(More)
White organic light-emitting diodes (WOLEDs) have attracted great attention for their potential use in full color displays and solid-state lighting applications due to several advantages, such as low cost and flexibility. To date, the most efficient WOLEDs have used small phosphorescent molecules in multilayer structured devices prepared by high vacuum(More)
Single-molecule-resolved scanning tunneling microscopy of tetra-tert-butyl azobenzene (TTB-AB) molecules adsorbed onto Au(111) reveals chirality selection rules in their photoswitching behavior. This observation is enabled by the fact that trans-TTB-AB molecules self-assemble into homochiral domains. Cis-TTB-AB molecules produced via photoisomerization are(More)
We have used scanning tunneling microscopy to investigate the structure and photoswitching behavior of azobenzene molecules functionalized with bulky spacer groups and adsorbed onto Au(111). We find that positioning tert-butyl "legs" in a canted arrangement on the azobenzene phenyl rings quenches photoisomerizability of the molecule on Au(111). Addition of(More)
While studies on the experimental photolytic and thermolytic extrusion of nitrogen from tert-butyldiazomethane and tert-butyldiazirine and the decomposition of other precursors have shown a mixture of C-H and C-C insertion products depending on conditions, the analogous trimethylsilyldiazomethane undergoes solely Si-C insertion. Description of the singlet(More)
New soluble quinacridone-based molecules have been developed as electron donor materials for solution-processed organic solar cells. By functionalizing the pristine pigment core of quinacridone with solubilizing alkyl chains and light absorbing/charge transporting thiophene units, i.e., bithiophene (BT) and thienylbenzo[c][1,2,5]thiadiazolethienyl (BTD), we(More)
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