The conductivity of films of treated nanocrystals increases

1. Thermally Degradable Ligands for NanocrystalsWayne L. Gladfelter, University of Minnesota-Twin Cities, DMR 0908629 Semiconductor nanocrystals are usually coated with a stabilizing layer to keep them dispersed in solution and allow easy processing. However, once the nanocrystals are processed into a device, this layer blocks the flow of electricity between particles. We developed a new stabilizing layer that can easily be removed after processing. In our method, a ligand with a weak chemical bond is attached to the surface, stabilizing the dispersion. Then, during processing, the device is gently heated, causing the bond to break and the stabilizing layer to evaporate. This leads to closer nanoparticle contact and enhanced conductivity, as shown on the right. Wills et al. ACS Nano, 2010, 4, pp. 4523-4530 Nanocrystals are treated with the novel ligand in solution and heated to remove it during device preparation. The conductivity of films of treated nanocrystals increases As the stabilizing layer is removed by heating.

2. International Student Exchange and MeetingsWayne L. Gladfelter, University of Minnesota-Twin Cities, DMR 0908629 • After completing a semester of undergraduate research in Prof. Norris’s lab, Donna Deng (a junior majoring in Materials Science at the U of M) spent 6 weeks this summer in Professor Winterer’s lab working on ZnOnanoparticles. • Thomas Bastuck, a Master’s student at Duisburg-Essen worked for 10 weeks this summer with Prof. Gladfelter on the atomic layer deposition of doped ZnO films. • Professors Gladfelter and Winterer co-organized a symposium at the spring meeting of the Materials Research Society in 2010 entitled “Photovoltaics and Optoelectronics from Nanoparticles” Please insert an image or group of images here to illustrate your broader impacts activities. If you need more space, you may reduce the adjacent textbox. Please use lettering that is clearly visible (i.e. not too small). Please include a brief figure caption. From the left, Katherine Stevens (Carthage College – now at the U of M), Hai Yuan (Xi’an, China) and Thomas Bastuck (Duisburg-Essen) comprised the ALD team during the summer of 2010.