Balancing the ambipolar conduction for pentacene thin film transistors through bifunctional electrodes

Abstract

We report an effective way to equilibrate hole and electron transport in ambipolar pentacene thin film transistors ͑TFTs͒. It was achieved by inserting an ultra thin lithium fluoride ͑LiF͒ layer at the electrode/organic interface to form a bifunctional source/drain electrode. It can be observed that the presence of ultrathin LiF layer will facilitate the injection of electrons from source/drain electrodes to organic semiconductor, resulting in a significant enhancement of the n-channel conduction, without sacrificing p-channel conduction for ambipolar pentacene TFTs. These factors make them potential candidates for the organic complementary circuits and inverter circuits of these ambipolar TFTs are also demonstrated.

Complementary‐Like Graphene Logic Gates Controlled by Electrostatic Doping

“…Although the ambipolar conduction behavior intrinsic to graphene hinders the feasibility of logic devices directly in a conventional complementary (CMOS) architecture, several methods have been recently developed. [6][7][8][9][10][11] Among them, a self-adaptive complementary-like architecture based on ambipolar transistors is especially interesting, [12][13][14][15][16] because the ambipolar nature is used as a benefit rather than a drawback to form logic devices. Free of doping, charge neutrality points (CNPs) of two involved transistors are controlled by a supply bias (V DD ) and the intrinsic pand n-conduction branches are delicately combined to construct a complementary geometry.…”

“…Within the CNP splitting region, a sharp voltage inversion forms due to the variation of resistance ratio between two transistors. Outside the CNP splitting region, a V OUT degradation arises, which is a unique feature of the ambipolar-transistor based complementary-like architecture; [12][13][14][15][16] this feature originates from the overlap of same carrier polarity (pp or nn combination). Two parameters are needed to evaluate the performance of this type of NOT gate.…”

Interface Engineering for Controlling Device Properties of Organic Antiambipolar Transistors

“…It is noteworthy that these depend on the threshold voltages ( V th ) of individual α-6T and PTCDI-C8 transistors. The threshold voltage of organic field-effect transistors (OFETs) is generally tunable by inserting charge-injection layers, such as WO 3 , MoO 3 , V 2 O 5 , Cs 2 CO 3 , or LiF layers. − These interlayers between the contact electrode and semiconducting channel layers effectively reduce the carrier injection barrier to decrease contact resistance, which suppresses the voltage drop at the interface. As a result, the threshold voltage is lowered.…”

Hybrid Materials for Integrated Photonics

“…Given the extremely wide properties shown by organic molecules, each of these key factors needs to be optimized looking at the specific system considered and there are only few, general, rules of thumb to predict/design systems with predefined characteristics. In organics devices, holes mobility is often several orders of magnitude greater than the electronics one [166]; thus a balanced injection of carriers, which is important to achieve high external efficiencies, requires a proper design of the device and in this context the multilayered structure allows for a certain degree of flexibility [167,168]. Figure 14(a) reports a pictorial view of an OLED crosssection with the main layers (sometimes hole and electron blocking layer are also added to improve the efficiency of the recombination within the emitting layer).…”