Surface engineering for high performance organic electronic devices: the chemical approach

Abstract

International audienceSelf-assembled monolayers (SAMs) are rapidly becoming an essential part of organic electronics such as light emitting diodes (LEDs), organic field-effect transistors (OFETs), and complementary circuits, where they are employed to control the morphology and energetics of the interfaces. This review will focus on interface engineering and its influence on such devices. We will describe the growth of SAMs of organic molecules on various surfaces of interest for this purpose (mainly metals and oxides). For the growth of SAMs on metal electrodes, the most common approach makes use of thiols to modify the metal surface, but the preparation of SAMs on dielectrics requires other reactive groups such as carboxylic or phosphonic acids. We review also the control of the interfacial properties by appropriate molecular design of the SAMs and their effect on device performance. SAMs can modify the morphology of the organic semiconductor, the dielectric properties of the insulator, the electronic states at the dielectric interface and the level alignment at the electrode interfaces. All these factors can influence current transport mainly by modifying the charge mobility, the contact resistance and the trap density at the interfaces

Electronic structure of interfaces with conjugated organic materials

“…(ii) Self-assembled monolayers with dipoles: The use of electrode surface-attached self-assembled monolayers (SAMs) comprising dipolar moieties has been shown to allow adjusting charge injection barriers towards organic semiconductors, having the Helmholtz equation as conceptual basis as well [63][64][65]. SAMs based on alkyl chains with thiol end-groups for covalent bonding to metals are frequently used.…”

Self-Assembly and Charge Transport of a Conjugated Polymer on ITO Substrates

“…Here in this paper we report a new approach and method of determining the electron transfer rates using a combination of cyclic voltammetry, atomic force microscopy, the Laviron method, and electrode kinetic calculations. Assembly of organic species on conducting substrates in the form of molecular wires and molecular assemblies have been widely studied, and within recent years, research have increased in polymer assemblies on varies conducting substrate [3,4,12]. Conjugated polymers end-functionalized with phosphonic acid anchoring groups have been grafted onto oxide substrates such as indium tin oxide (ITO) [5,[13][14][15][16], zinc oxide [17], silicon dioxide (SiO 2 ) [18], titanium dioxide (TiO 2 ) [19,20], and aluminium oxide (Al 2 O 3 ) [21].…”

“…Self-assembly and covalent attachment of conjugated organic and polymeric materials on conducting substrates are essential for the development of future generation polymer based electronic and optoelectronic devices, and electron transfers between organic or polymeric species and electrodes are also essential [1][2][3][4]. There are a number of methods used to measure electron transfer between the organic species and the conducting substrate, for example, Voltammetric or impedancebased methods [5,6].…”

Theoretical Evaluation of Mass Transfer Coefficients in Solution Crystallization

“…Relevant examples are found in pharmaceutical, high-performance polymer and electronic industries (Chen et al, 2011;Miozzo et al, 2010;Huang et al, 2012 andSu et al, 2013). Despite its importance, very little is known about solid-liquid mass transfer coefficients in crystallization.…”