AVS 50th International Symposium
    Contacts to Organic Materials Topical Conference Monday Sessions
       Session OM-MoM

Invited Paper OM-MoM1
Coupling Molecules to Electronic Materials Chemical Bonding and Polarization Effects at Metal-Molecular Monolayer-Semiconductor Junctions

Monday, November 3, 2003, 8:20 am, Room 318/319

Session: Contacts to Molecules and Molecular Films (I)
Presenter: D. Cahen, Weizmann Institute of Science, Israel
Correspondent: Click to Email
All-molecular nm scale optoelectronic devices face many practical and fundamental obstacles, which,however,do not preclude use of molecules to control hybrid devices. In such systems nm- or even sub-nm molecular structures need to be incorporated in device structures. Judicious choice of such systems allows, apart from potentially practical possibilities, fundamental investigations of the effects, limitations and possibilities of molecules in optoelectronics. By placing molecules at metal-semiconductor interfaces, even if only as poorly organized, partial, rather than ideal monolayers, they can control these interfaces electronically.@footnote 1@ This is primarily because electron energetics at interfaces determine the electronic behaviour of semiconductor & metal contacts.@footnote 2@ Normal requirement for (near-)ideally structured monolayers can be relaxed because the molecules can act as "gatekeepers", i.e., electrostatically rather than -dynamically. This leads to molecular devices, with no current flow through molecules.@footnote 1@ Devices are made reproducibly because soft contacting methods were developed.@footnote 3@ These also show how intimate contact between molecules and metal can polarize the contacts.@footnote 1,3@ In systems with near-ideal molecular films, molecules electronic transport through molecules is often by "through bond" tunneling.@footnote 4@ Experimental evidence is accumulating both from our and other groups, that in most devices with molecules, the nature of the molecule/electrode contact is crucial for the resulting junction.@footnote 4,5@ @FootnoteText@ @footnote 1@ A.Vilan et al. Nature404(2000)166;J.Phys.Chem B, in press; G.Ashkenasy et al. Acc.Chem.Res.35(2002)121@footnote 2@ D.Cahen, A.Kahn, Adv. Mater.,14(2003)271@footnote 3@ A.Vilan, D.Cahen, Adv.Funct.Mater.12(2002)795; H. Haick et al., to be published@footnote 4@ Y.Selzer et al.,J.Phys.Chem.B 106(2002)10432;D.Cahen,G.Hodes, Adv.Mater. 14(2002)789@footnote 5@ Y.Selzer et al.,Angew.Chem.Int.Ed., 41(2002)827.