title: Single-crystal organic charge-transfer interfaces probed using Schottky-gated heterostructures.
abstract: Organic semiconductors based on small conjugated molecules generally behave as insulators when undoped, but the heterointerfaces of two such materials can show electrical conductivity as large as in a metal. Although charge transfer is commonly invoked to explain the phenomenon, the details of the process and the nature of the interfacial charge carriers remain largely unexplored. Here we use Schottky-gated heterostructures to probe the conducting layer at the interface between rubrene and PDIF-CN(2) single crystals. Gate-modulated conductivity measurements demonstrate that interfacial transport is due to electrons, whose mobility exhibits band-like behaviour from room temperature to ~150 K, and remains as high as ~1 cm(2) V(-1) s(-1) at 30 K for the best devices. The electron density decreases linearly with decreasing temperature, an observation that can be explained quantitatively on the basis of the heterostructure band diagram. These results elucidate the electronic structure of rubrene/PDIF-CN(2) interfaces and show the potential of Schottky-gated organic heterostructures for the investigation of transport in molecular semiconductors.
authors: DPMC and GAP, University of Geneva, 24 quai Ernest Ansermet, CH1211 Geneva, Switzerland.
authors: Ignacio
authors: I
authors: Gutiérrez Lezama
authors: Masaki
authors: M
authors: Nakano
authors: Nikolas A
authors: NA
authors: Minder
authors: Zhihua
authors: Z
authors: Chen
authors: Flavia V
authors: FV
authors: Di Girolamo
authors: Antonio
authors: A
authors: Facchetti
authors: Alberto F
authors: AF
authors: Morpurgo