Light-emitting ambipolar organic heterostructure field-effect transistor

Abstract

We have investigated ambipolar charge injection and transport in organic field-effect transistors (OFETs) as prerequisites for a lightemitting organic field-effect transistor (LEOFET). OFETs containing a single material as active layer generally function either as a p-or an n-channel device. Therefore, ambipolar device operation over a wide range of operating voltages is difficult to realize. Here, we present a highly asymmetric heterostructure OFET architecture using the hole transport material pentacene and the electron transport material N,Nditridecylperylene-3,4,9,10-tetracarboxylic diimide (PTCDI-C 13 H 27). Efficient charge carrier injection is achieved by using Au as bottom contact for hole injection into pentacene and Mg as top contact for electron injection into PTCDI-C 13 H 27. The device characteristic of this asymmetric heterostructure shows all features of ambipolar operation. For example, a typical transistor characteristic with a linear and saturation region is observed for small drain-source voltage V DS. For large V DS , the current increases due to additional injection of charge carriers of opposite sign from the drain contact. In that regime, both types of charge carriers are present in the device. Thus, the thin-film transistor can be operated in a mixed state in which both electron and hole currents are transported within the device and where the double injection regime is controlled by the gate voltage. Our device exhibits electron and hole mobilities of 3 × 10 −3 cm 2 /Vs and 1 × 10 −4 cm 2 /Vs, respectively. Investigation of a bulk heterostructure of a thienylene derivative and PTCDI-C 13 H 27 results in a light-emitting field-effect transistor. The light emission is controlled by both the drain-source voltage V DS and the gate voltage V G .

Light-emitting organic field-effect transistor using an organic heterostructure within the transistor channel

“…20 At a certain drain voltage, the electron current in the n-type material at the p-n interface is equal to the hole current in the p-type material. In contrast to previously published LEOFETs, 15,16,19 increasing |V D | beyond this voltage leads to a saturation of the current. This is explained by the fact that a further increase of |V D | does not lead to an increase of the hole current.…”

“…12,13 Rost et al reported on a LEOFET in which the active layer was formed by a heterostructure of a ptype and an n-type organic semiconductor, either by coevaporation 14 or by subsequent evaporation of both semiconductors. 15 The presence of an n-type and p-type semiconductor is a clear advantage in comparison to tetracene-based p-type-only LEOFETs. However, as neither of the semiconductors is patterned, there is little control over the position in the channel where the light is emitted.…”

Near‐Infrared Light‐Emitting Ambipolar Organic Field‐Effect Transistors

“…[3][4][5][6][7][8] Only recently light emission from within the transistor channel was demonstrated in ambipolar OFETs (i.e., capable of transporting both holes and electrons). [9][10][11][12][13][14] In an ambipolar LEOFET when the gate is biased in between the source and drain potentials, holes and electrons are injected simultaneously at the opposite ends of the channel. At the point where the local potential within the channel equals the gate potential a pn-junction is formed at which opposite carriers can recombine to form excitons.…”

Conjugated polyelectrolytes for organic light emitting transistors

“…[1][2][3][4][5][6][7][8][9][10][11] Due to this unique combination of properties, LEFETs have potential applications in the fabrication of simplified pixels for flat panel displays, optical communication devices, and electrically driven organic lasers. [12][13][14][15][16] Injection and transport of both electrons and holes are important requirements for generating electroluminescence in LEFETs.…”