Organic and printed electronics technologies require conductors with a work function that is sufficiently low to facilitate the transport of electrons in and out of various optoelectronic devices. We show that surface modifiers based on polymers containing simple aliphatic amine groups substantially reduce the work function of conductors including metals, transparent conductive metal oxides, conducting polymers, and graphene. The reduction arises from physisorption of the neutral polymer, which turns the modified conductors into efficient electron-selective electrodes in organic optoelectronic devices. These polymer surface modifiers are processed in air from solution, providing an appealing alternative to chemically reactive low-work function metals. Their use can pave the way to simplified manufacturing of low-cost and large-area organic electronic technologies.

During the last few years, transition metal oxides (TMO) such as molybdenum tri-oxide (MoO(3) ), vanadium pent-oxide (V(2) O(5) ) or tungsten tri-oxide (WO(3) ) have been extensively studied because of their exceptional electronic properties for charge injection and extraction in organic electronic devices. These unique properties have led to the performance enhancement of several types of devices and to a variety of novel applications. TMOs have been used to realize efficient and long-term stable p-type doping of wide band gap organic materials, charge-generation junctions for stacked organic light emitting diodes (OLED), sputtering buffer layers for semi-transparent devices, and organic photovoltaic (OPV) cells with improved charge extraction, enhanced power conversion efficiency and substantially improved long term stability. Energetics in general play a key role in advancing device structure and performance in organic electronics; however, the literature provides a very inconsistent picture of the electronic structure of TMOs and the resulting interpretation of their role as functional constituents in organic electronics. With this review we intend to clarify some of the existing misconceptions. An overview of TMO-based device architectures ranging from transparent OLEDs to tandem OPV cells is also given. Various TMO film deposition methods are reviewed, addressing vacuum evaporation and recent approaches for solution-based processing. The specific properties of the resulting materials and their role as functional layers in organic devices are discussed.

The field of organic thin films and devices is progressing at an extremely rapid pace. Organic–metal and organic–organic interfaces play crucial roles in charge injection into, and transport through, these devices. Their electronic structure, chemical properties, and electrical behavior must be fully characterized and understood if the engineering and control of organic devices are to reach the levels obtained for inorganic semiconductor devices. This article provides an extensive, although admittedly nonexhaustive, review of experimental work done in our group on the electronic structure and electrical properties of interfaces between films of π‐conjugated molecular films and metals. It introduces several mechanisms currently believed to affect the formation of metal–organic interface barriers. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2529–2548, 2003

Direct and inverse photoemission spectroscopies are used to determine materials electronic structure and energy level alignment in hybrid organic-inorganic perovskite layers grown on TiO 2 . The results provide a quantitative basis for the analysis of perovskite-based solar cell performance and choice of an optimal hole-extraction layer.

We present a concise, although admittedly non‐exhaustive, but hopefully didactic review and discussion of some of the central and basic concepts related to the energetics of surfaces and interfaces of solids. This is of particular importance for surfaces and interfaces that involve organic molecules and molecular films. It attempts to pull together different views and terminologies used in the solid state, electrochemistry, and electronic device communities, regarding key concepts of local and absolute vacuum level, surface dipole, work function, electron affinity, and ionization energy. Finally, it describes how standard techniques like photoemission spectroscopy can be used to measure such quantities.