Organic Materials of Intermediate Dimensions for Optoelectronic Technologies

Guillermo C. Bazan (UCSB), DMR-0087611

Chemical Synthesis provides for the ability to create molecular structures that address specific fundamental problems related to charge transport across metal-molecule-metal junctions. Contacting two gold surfaces by a bridge containing the [2.2]paracyclophane structure allows for the examination of through-space electron transfer across a well-defined molecular gap. The resulting current/voltage dependence reveals that suitably arranged -systems can be very efficient at promoting charge transport. Future possible molecular electronic applications of this basic knowledge base include the creation of self-assembled, multi chromophore structures with strong inter-molecular delocalization and excellent charge transport characteristics.

Graphic illustration of charge transport across a molecular junction with though-bond (1,A) and through-space (2, B) electronic communication.

Seferos, D. S.; Trammell, S. A.; Bazan, G. C.; Kusmerick, J. G. Proceedings of the National Academy of Sciences, USA, 2005, 102, 8821 .

SRRS

RSSR

CHOMeS

MeS

R = MeR = Ac

R = MeR = Ac

1

2

i

ii

iii

iv

iv

Organic Materials of Intermediate Dimensions for Optoelectronic Technologies

Guillermo C. Bazan (UCSB), DMR-0087611

Conjugated polymer blends are used as the active material in optically pumped lasers and light emitting diodes. Reduction of self absorption, via Förster energy transfer from an absorbing polymer host to an emitting guest polymer leads to increases in the photoluminescence efficiency and to a decrease in the threshold for amplified spontaneous emission. Problems arise from the spontaneous driving force for phase separation in polymer blends and therefore incomplete energy transfer. A new approach was demonstrated where low energy optical “defects” are introduced in small percentages within the polymer backbone, leading to all of the advantages observed with the polymer blends, No phase separation is possible for the new materials.

Vehse, M.; Liu, B.; Edman, L.; Bazan, G. C.; Heeger, A.J. Adv. Mater. 2004, 1001.

Education and Outreach

-Three to four undergraduate students and high school teachers do summer internships or thesis work in Bazan’s Labs working in the area of organic conjugated polymers and oligomers.

-Bazan hosted and gave lectures to high school students from local farming communities who attend week-long workshops at UCSB to find out more about college studies and the lifestyle of the scientist.

High school students and Bazan during a summer internship workshop.

Organic Materials of Intermediate Dimensions for Optoelectronic Technologies

Guillermo C. Bazan (UCSB), DMR-0087611