Ambipolar Organic Field-Effect Transistors Based on Indigo Derivatives

Abstract

In order to improve the ambipolar performance of indigo-based semiconductors, we have investigated halogen-substituted (1-4) and phenyl-substituted (5) indigo derivatives at the 5-position. We show that introduction of iodine atoms, namely 5,5'-diiodoindigo (4), leads to the strong halogen-halogen interaction (iodine-iodine interaction) that gives a significant effect on the molecular packing. Thanks to the supramolecular network coming from the extra iodine-iodine interaction, the molecules are arranged approximately perpendicular to the substrate in the thin film. This results in remarkable transistor performance of the maximum hole and electron mobilities (µh/µe) = 0.42/0.85 cm 2 V-1 s-1 , which are one of the highest among small-molecule ambipolar organic transistors. Furthermore, introducing phenyl groups, 5 improves the transistor performances up to the maximum mobilities µh/µe = 0.56/0.95 cm 2 V-1 s-1. We have found that the phenyl groups destroy the standard molecular packing of indigo to achieve a unique structure that is a hybrid of the herringbone and brickwork structures.

Small-molecule ambipolar transistors

“…4(d)). 105,106 Furthermore, 5phenyl substitution (IG-10) provides a novel two-dimensional (2D) molecular arrangement with brickwork and herringbone hybrid molecular packing (Fig. 4(e)).…”

Organic Semiconductors based on Dyes and Color Pigments

“…[112a,b] They further managed to electropolymerize ID3 to give PID3 whose charge‐carrier mobility did not exceed 10 −3 cm 2 V −1 s −1 . In 2015, Pitayatanakul et al could push the performance to impressive values of μ n / μ p = 0.95/0.56 cm 2 V −1 s −1 for vacuum‐deposited phenyl‐substituted indigo ID2 for which the phenyl substituents induce a unique structure that may be regarded as a hybrid between a herringbone and a brick‐wall packing arrangement . For another indigo derivative, epindolidione (EP1) which can be obtained by thermal rearrangement of indigo ID1 at 460 °C, Głowacki and Sariciftci reported even higher hole carrier mobilities up to μ p = 1.5 cm 2 V −1 s −1 for vacuum‐deposited thin films …”

Study of Electrochemical Properties of Compared Indigo for Metal–Semiconductor–Metal Diode

“…Many researchers have discovered that indigo blue pigment has organic semiconductor properties because of its strength of intermolecular interactions, best charging transport, and responsible ultrafast proton transfers [9]. Based on those remarkable properties, the indigo blue pigment has been widely used in many electronic semiconductor devices, such as indigo-derivative-organic field-effect transistors, FETs, organic light-emitting diodes, LEDs, and metal-semiconductor-metal diodes, MSM diodes [10][11][12][13][14].…”