Thin Films of Highly Planar Semiconductor Polymers Exhibiting Band-like Transport at Room Temperature.

We report the observation of band-like transport from printed polymer thin films at room temperature. This was achieved from donor-acceptor type thiophene-thiazole copolymer that was carefully designed to enhance the planarity of the backbone and the resulting transfer integral between the macromolecules. Due to the strong molecular interaction, the printed polymer film exhibited extremely low trap density comparable to that of molecular single crystals.

Dibenzothiopheno[6,5-b:6',5'-f]thieno[3,2-b]thiophene (DBTTT): high-performance small-molecule organic semiconductor for field-effect transistors.

We present the synthesis, characterization, and structural analysis of a thiophene-rich heteroacene, dibenzothiopheno[6,5-b:6',5'-f]thieno[3,2-b]thiophene (DBTTT) as well as its application in field-effect transistors. The design of DBTTT is based on the enhancement of intermolecular charge transfer through strong S-S interactions. Crystal structure analysis showed that the intermolecular π-π distance is shortened and that the packing density is higher than those of the electronically equivalent benzene analogue, dinaphtho-[2,3-b:2',3'-f]thieno[3,2-b]thiophene (DNTT).

Reliable and uniform thin-film transistor arrays based on inkjet-printed polymer semiconductors for full color reflective displays.

Stable uniform performance inkjet-printed polymer transistor arrays, which allow demonstration of flexible full-color displays, were achieved by new ambient processable conjugated copolymer semiconductor, and OTFT devices incorporating this material showed high mobility values>1.0 cm2 V(-1) s(-1). Bias-stress stability of the devices was improved with a channel-passivation layer, which suppresses the density of trap states at the channel interface.

Design of a polymer-carbon nanohybrid junction by interface modeling for efficient printed transistors.

Molecularly hybridized materials composed of polymer semiconductors (PSCs) and single-walled carbon nanotubes (SWNTs) may provide a new way to exploit an advantageous combination of semiconductors, which yields electrical properties that are not available in a single-component system. We demonstrate for the first time high-performance inkjet-printed hybrid thin film transistors with an electrically engineered heterostructure by using specially designed PSCs and semiconducting SWNTs (sc-SWNTs) whose system achieved a high mobility of 0.23 cm(2) V(-1) s(-1), no V(on) shift, and a low off-current.

Fabrication and evaluation of solution-processed reduced graphene oxide electrodes for p- and n-channel bottom-contact organic thin-film transistors.

Reduced graphene oxide (RGO) is an electrically conductive carbon-based nanomaterial that has recently attracted attention as a potential electrode for organic electronics. Here we evaluate several solution-based methods for fabricating RGO bottom-contact (BC) electrodes for organic thin-film transistors (OTFTs), demonstrate functional p- and n-channel devices with such electrodes, and compare their electrical performance with analogous devices containing gold electrodes. We show that the morphology of organic semiconductor films deposited on RGO electrodes is similar to that observed in the channel region of the devices and that devices fabricated with RGO electrodes have lower contact resistances compared to those fabricated with gold contacts.

Liquid-crystalline semiconducting copolymers with intramolecular donor-acceptor building blocks for high-stability polymer transistors.

The ability to control the molecular organization of electronically active liquid-crystalline polymer semiconductors on surfaces provides opportunities to develop easy-to-process yet highly ordered supramolecular systems and, in particular, to optimize their electrical and environmental reliability in applications in the field of large-area printed electronics and photovoltaics. Understanding the relationship between liquid-crystalline nanostructure and electrical stability on appropriate molecular surfaces is the key to enhancing the performance of organic field-effect transistors (OFETs) to a degree comparable to that of amorphous silicon (a-Si). Here, we report a novel donor-acceptor type liquid-crystalline semiconducting copolymer, poly(didodecylquaterthiophene-alt-didodecylbithiazole), which contains both electron-donating quaterthiophene and electron-accepting 5,5'-bithiazole units.

Transfer of photoenergy in pi-conjugated polymers. Two types of photoluminescence that involve energy transfer along a polymer chain.

Two types of energy transfer in pi-conjugated polymers have been investigated using time-resolved photoluminescence (PL) techniques: type i, perpendicular-type energy transfer from the 2,3-di(p-tolyl)quinoxaline unit to the pi-conjugated main chain of poly[2,3-di(p-tolyl)quinoxaline-5,8-diyl], and type ii, parallel-type energy transfer from the oligo(pyridine-2,5-diyl) (O-Py) unit to the oligo(selenophene-2,5-diyl) (O-Se) unit in a block-type copolymer of O-Py and O-Se. Both types of energy transfer were very fast with a time constant shorter than approximately 0.1 ns; in particular, the type ii energy transfer took place with a time constant of approximately 5 ps.