摘要
Interfacial charge transfer plays an essential role in establishing the relative alignment of the metal Fermi level and the energy bands of organic semiconductors.While the details remain elusive in many systems,this charge transfer has been inferred in a number of photoemission experiments.We present electronic transport measurements in very short channel(L<100 nm)transistors made from poly(3-hexylthiophene)(P3HT).As channel length is reduced,the evolution of the contact resistance and the zero gate voltage conductance are consistent with such charge transfer.Short channel conduction in devices with Pt contacts is greatly enhanced compared to analogous devices with Au contacts,consistent with charge transfer expectations.Alternating current scanning tunneling microscopy(ACSTM)provides further evidence that holes are transferred from Pt into P3HT,while much less charge transfer takes place at the Au/P3HT interface.
基金
The authors gratefully acknowledge Jun Zhang for experimental assistance,Paul Weiss for useful discussions,Prof.J.W.Ciszek and Prof.J.M.Tour for synthesis of the F-OPE molecule,and the support from NSF grant ECCS-0601303
R.Giridharagopal acknowledges the support of an NSF graduate fellowship.D.Natelson also aknowledges the David and Lucille Packard Foundation,the Alfred P.Sloan Foundation,the Robert A.Welch Foundation,and the Research Corporation.K.F.Kelly also acknowledges the Rochester MURI on Nanoscale Subsurface Spectroscopy and Tomography(F49620-031-0379),administered by the Air Force Office of Scientific Research.
