Phenyl cored thiophene dendrimers: Synthesis and application in photovoltaic devices

PMSE 253

William J. Mitchell, william_mitchell@nrel.gov1, Nikos Kopidakis2, William L. Rance3, Garry Rumbles, garry_rumbles@nrel.gov2, David S. Ginley, david_ginley@nrel.gov1, and Sean E. Shaheen, sshaheen@nrel.gov4. (1) National Renewable Energy Laboratory, 1617 Cole Blvd, Golden, CO 80401, (2) Center for Basic Sciences, National Renewable Energy Laboratory, 1617 Cole Blvd, Golden, CO 80401, (3) Department of Physics, Colorado School of Mines, 1523 Illinois Street, Golden, CO 80401, (4) National Center for Photovoltaics, National Renewable Energy Laboratory, 1617 Cole Blvd, Golden, CO 80401
We are exploring the potential of conjugated dendrimers to replace polymers in organic photovoltaic devices. Dendrimers, which are monodisperse macromolecules consisting of dendrons attached to a central core, pose advantages for use in optoelectronic devices as a result of their well-defined molecular weight, improved batch-to-batch reproducibility and a higher degree of purity. We have prepared a range of thiophene based, phenyl cored dendrimers with optical band-gaps ranging from 2.2 - 2.6 eV. The band-gap is dependent on the conjugation length and number of dendrons around the core. Photocurrent and solar cell performance is seen to increase systematically with the length of the dendron. Solar cells with a peak external quantum efficiency of 35% and power conversion efficiency of 1.3% were fabricated by blending the dendrimer with a band-gap of 2.2 eV with PCBM. We also show how the band-gap can be reduced to 1.8 eV by incorporating electron-withdrawing groups.
 

Joint PMSE/POLY Poster Session
6:00 PM-8:00 PM, Tuesday, 12 September 2006 Moscone Center -- Hall D, Poster

Sci-Mix
8:00 PM-10:00 PM, Monday, 11 September 2006 Moscone Center -- Hall D, Sci-Mix

Division of Polymeric Materials: Science & Engineering

The 232nd ACS National Meeting, San Francisco, CA, September 10-14, 2006