Approaching disorder-free transport in high-mobility conjugated polymers.

Conjugated polymers enable the production of flexible semiconductor devices that can be processed from solution at low temperatures. Over the past 25 years, device performance has improved greatly as a wide variety of molecular structures have been studied. However, one major limitation has not been overcome; transport properties in polymer films are still limited by pervasive conformational and energetic disorder. This not only limits the rational design of materials with higher performance, but also prevents the study of physical phenomena associated with an extended π-electron delocalization along the polymer backbone. Here we report a comparative transport study of several high-mobility conjugated polymers by field-effect-modulated Seebeck, transistor and sub-bandgap optical absorption measurements. We show that in several of these polymers, most notably in a recently reported, indacenodithiophene-based donor-acceptor copolymer with a near-amorphous microstructure, the charge transport properties approach intrinsic disorder-free limits at which all molecular sites are thermally accessible. Molecular dynamics simulations identify the origin of this long sought-after regime as a planar, torsion-free backbone conformation that is surprisingly resilient to side-chain disorder. Our results provide molecular-design guidelines for 'disorder-free' conjugated polymers.We gratefully acknowledge financial support from the Engineering and Physical Sciences Research Council (EPSRC) through a programme grant (EP/G060738/1) and the Technology Strategy Board (TSB) (PORSCHED project). D. Venkateshvaran acknowledges financial support from the Cambridge Commonwealth Trust through a Cambridge International Scholarship. K. Broch acknowledges post-doctoral fellowship support from the German Research Foundation (DFG). Mateusz Zelazny acknowledges funding from the NanoDTC in Cambridge. The work in Mons was supported by the European Commission / Région Wallonne (FEDER – Smartfilm RF project), the Interuniversity Attraction Pole program of the Belgian Federal Science Policy Office (PAI 7/05), Programme d’Excellence de la Région Wallonne (OPTI2MAT project) and FNRS-FRFC. D.B. and J.C. are FNRS Research Fellows.This is the accepted manuscript. The final version's available from Nature at http://www.nature.com/nature/journal/vaop/ncurrent/full/nature13854.html

In-Panel 31.17dB 140kHz 87μW Unipolar Dual-Gate In-Ga-Zn-O Charge-Sense Amplifier for 500dpi Sensor Array on Flexible Displays

In this paper a charge sense amplifier (CSA) using a 5um In-Ga-Zn-O transistor technology on 15um thick flexible substrate is presented for readout of a 500dpi fingerprint sensor array targeting direct integration with active matrix organic light emitting displays (AMOLED). The CSA achieves a linear input range of 0.8V for rail to rail output at VDD=15V. The CSA comprises of a high gain and stable dual-ended output dual-stage amplifier. The n-type load is driven by a dual-stage buffer and start-up circuit to increase the performance and ensure stability. The amplifier operates down to 6V supply voltage. It achieves 31.17dB DC-gain, 140kHz gain-bandwidth, 53$°$ phase margin and dissipates 87uW at 15V. The footprint of the CSA is 0.3mm2and enables 1fps readout of 1 megapixel 500dpi sensor array.keywords: Thin film transistors,Logic gates,Resistance,amplifier,Dielectrics,igzo,Sensor arrays,Gain,metal-oxide,amoled,dual gate,csa,display,imager,in-panelstatus: publishe

Measurements of Ambipolar Seebeck Coefficients in High-Mobility Diketopyrrolopyrrole Donor–Acceptor Copolymers

AbstractThe Seebeck coefficient of both electrons and holes in a family of ambipolar diketopyrrolopyrrole copolymers is investigated using field‐effect gated measurements. It is found that at high carrier concentrations the magnitude of the Seebeck coefficients is not strongly dependent on the molecular structure of the backbone within this family of polymers. Additionally, the Seebeck coefficients of electrons and holes have very similar magnitudes showing that electrons and holes experience a similar energetic landscape. Subtle differences in the carrier concentration dependence between the polymers are observed, which are interpreted in terms of different degrees of energetic disorder on the basis of molecular dynamics and electronic structure simulations.</jats:p

Dual-gate self-aligned IGZO TFTs monolithically integrated with high-temperature bottom moisture barrier for flexible AMOLED

© 2018, Blackwell Publishing Ltd. All rights reserved. We present a 350°C self-aligned dual-gate a-IGZO backplane technology with a monolithically integrated multi-layer high-temperature thin-film barrier for flexible AMOLED. Thin-film barrier properties and TFT technology are optimized on 320 x 352mm substrates, and demonstrated in a flexible QQVGA 100 ppi AMOLED display prototype.status: publishe