Molecular Conductors By Adam Krause 41707 Physics 672

Molecular Conductors By: Adam Krause 4/17/07 Physics 672 1

Molecular Conductor Quick Intro. Ø Two types of molecules: carbon nanotubes and polyphenylene-based molecules Ø Multiple approaches to conductance experiments Ø Molecular conductors as applied to molecular electronics 2

Polyphenylene-based molecules Figure adapted from: Ellenbogen, J. C. and J. C. Love, Proceedings of the IEEE, Vol. 88 No. 3, (2000) 386 3

Mechanically Controlled Break. Junction Method Benzene-1, 4 -dithiolate Figures from: Reed, M. A. , et al. , Science 278, (1997) 252 4

Mechanically Controlled Break. Junction Method Benzene-1, 4 -dithiolate Figures from: Reed, M. A. , et al. , Science 278, (1997) 252 5

Crossed-Wire Method Oligo(phenylene ethynylene) Figure from: Kushmerick, J. G. , et al. , Phys. Rev. Lett 89, (2002) 086802 6

Crossed-Wire Method Oligo(phenylene ethynylene) Figure from: Kushmerick, J. G. , et al. , Phys. Rev. Lett 89, (2002) 086802 7

STM Break-Junction Method Many Thiolated Molecules Used Figure from: Xiao, X. , et al. , Nano. Lett. 4, (2004) 267 8

STM Break-Junction Method Many Thiolated Molecules Used Figure from: Xu, B. Q. and N. J. Tao, Science 307, (2003) 1221 9

Conductance Summary The various polyphenylene-based molecules shown here exhibit conductive properties. Ø These properties can change based on the electrode-molecule bond. Ø There are several approaches to measuring the conductance and current of a molecule Ø 10

Applications Diode Figure from: Ellenbogen, J. C. and J. C. Love, Proceedings of the IEEE, Vol. 88 No. 3, (2000) 386 11

Applications Logic Gates Figure from: Ellenbogen, J. C. and J. C. Love, Proceedings of the IEEE, Vol. 88 No. 3, (2000) 386 12

Applications Memory Figures from: Chen, J. , et al. , Ann. N. Y. Acad. Sci. 960, (2002) 69 13

Summary The conductance of functionalized polyphenylene-based molecules can be tailored to behave in a desired manner. Ø In theory, diode molecules are possible. Ø These diodes can be used to build more complex molecular electronic devices. Ø The persistent conductance states of some molecules can be utilized for molecular memory applications. Ø 14

References 1. 2. 3. 4. 5. Ellenbogen, J. C. and J. C. Love, Proceedings of the IEEE, Vol. 88 No. 3, (2000) 386 Reed, M. A. , et al. , Science 278, (1997) 252 Kushmerick, J. G. , et al. , Phys. Rev. Lett 89, (2002) 086802 Xiao, X. , et al. , Nano. Lett. 4, (2004) 267 Xu, B. Q. and N. J. Tao, Science 307, (2003) 1221 6. Chen, J. , et al. , Ann. N. Y. Acad. Sci. 960, (2002) 69 15