Electron and ambipolar transport in organic field-effect transistors.

Acenes have long been the subject of intense study because of the unique electronic properties associated with their pi-bond topology. Recent reports of impressive semiconductor properties of larger homologues have reinvigorated research in this field, leading to new methods for their synthesis, functionalization, and purification, as well as for fabricating organic electronic components. Studies performed on high-purity acene single crystals revealed their intrinsic electronic properties and provide useful benchmarks for thin film device research. New approaches to add functionality were developed to improve the processability of these materials in solution. These new functionalization strategies have recently allowed the synthesis of acenes larger than pentacene, which have hitherto been largely unavailable and poorly studied, as well as investigation of their associated structure/property relationships.

The larger acenes: versatile organic semiconductors.

Organic electron-transporting materials are essential for the fabrication of organic p-n junctions, photovoltaic cells, n-channel field-effect transistors, and complementary logic circuits. Rylene diimides are a robust, versatile class of polycyclic aromatic electron-transport materials with excellent thermal and oxidative stability, high electron affinities, and, in many cases, high electron mobilities; they are, therefore, promising candidates for a variety of organic electronics applications. In this review, recent developments in the area of high-electron-mobility diimides based on rylenes and related aromatic cores, particularly perylene- and naphthalene-diimide-based small molecules and polymers, for application in high-performance organic field-effect transistors and photovoltaic cells are summarized and analyzed.

Rylene and related diimides for organic electronics.

Over the past 20 years, organic transistors have developed from a laboratory curiosity to a commercially viable technology. This critical review provides a short summary of several important aspects of organic transistors, including materials, microstructure, carrier transport, manufacturing, electrical properties, and performance limitations (200 references).

Organic thin-film transistors.

Organic semiconductors have been the subject of intensive academic and commercial interest over the past two decades, and successful commercial devices incorporating them are slowly beginning to enter the market. Much of the focus has been on the development of hole transporting, or p-type, semiconductors that have seen a dramatic rise in performance over the last decade. Much less attention has been devoted to electron transporting, or so called n-type, materials, and in this paper we focus upon recent developments in several classes of n-type materials and the design guidelines used to develop them.

n-Type organic semiconductors in organic electronics.

One important technical hurdle that has to be overcome for using organic transistors in radio-frequency identification tags is for these devices to operate at rf frequencies (typically 13.56MHz) in the front end. It was long thought that organic transistors are too slow for this. In this letter we show that organic transistor based full-wave rectifier circuits utilizing pentacene, a p-channel organic semiconductor, can operate at this frequency with a useful efficiency. In order to achieve such high-frequency operation, we make use of the nonquasistatic state of the transistors.

Radio frequency rectifiers based on organic thin-film transistors

Surface polarization in a poly(4-vinyl phenol) (PVP) dielectric induced by water molecules has been qualitatively investigated in pentacene thin-film transistors. The magnitudes of drain currents from devices with PVP dielectrics subject to specific surface treatments increased with humidity, whereas the opposite responses were observed from device with SiO2 dielectrics. The increase in drain current is attributed to the accumulation of extra charge carriers induced by the surface polarization in addition to that by the vertical electric field. Such polarization effects should be carefully considered in characterizing organic and polymer thin-film transistors, particularly those with polymeric gate insulators.

Moisture induced surface polarization in a poly(4-vinyl phenol) dielectric in an organic thin-film transistor

High-performance solution-deposited n-channel organic transistors and their complementary circuits

A method for fabricating a touch sensor panel is disclosed. The method includes providing a substrate for the touch sensor panel, depositing a conductive material layer on a top surface of the substrate, depositing a metal layer on top of the conductive material layer, affixing a resist to a first area of the metal layer, the resist also adapted to serve as a passivation layer during passivation, removing metal from the metal layer outside of the first area; and performing passivation on the substrate while leaving the affixed resist intact.

Method for fabricating touch sensor panels

Processes for fabricating compact touch sensors for touch sensitive devices are disclosed. A process can include providing a touch sensor structure having a substrate, a first layer disposed on the substrate, and a second layer disposed on the first layer. The second layer can have an ablation fluence value that is lower than an ablation fluence value of the first layer. The process can include patterning the second layer with a laser emitting energy having a fluence value greater than or equal to the ablation fluence value of the second layer and less than the ablation fluence value of the first layer. The process can further include etching at least a portion of the first layer that was exposed during the patterning of the second layer. At least a portion of the second layer can then be removed by etching or laser ablation.

Siddharth Mohapatra

Papers

Radio frequency rectifiers based on organic thin-film transistors

Moisture induced surface polarization in a poly(4-vinyl phenol) dielectric in an organic thin-film transistor

High-performance solution-deposited n-channel organic transistors and their complementary circuits

Method for fabricating touch sensor panels

Partial laser ablation sensor process