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A ZnO thin-film transistor (TFT) with a channel layer formed via aqueous solution-growth at low temperature is demonstrated. This ZnO thin-film semiconductor has a well-controlled crystalline form, exhibiting n-channel, enhancement-mode behavior with a channel mobility as large as 0.56 cm2 V-1 s-1. Low-cost, superior transistor characteristics and low-temperature processing makes ZnO TFT attractive for flexible electronics on temperature sensitive substrates. [ABSTRACT FROM AUTHOR]

A donor-acceptor polymer of (3 E,7 E)-3,7-bis(2-oxoindolin-3-ylidene)benzo[1,2- b : 4,5- b′]difuran-2,6(3 H,7 H)-dione (IBDF) and bithiophene (BT) exhibits typical ambipolar charge transport behaviour in organic thin film transistors. Using the electron rich triphenylamine as an end capping group, a notable suppression of hole transport is observed. This interesting phenomenon is accounted for by the hole trapping effect of the triphenylamine end-capper. Thus, this study provides a novel and facile approach to tuning the charge carrier polarity of a polymer semiconductor from ambipolar to n-type dominant. [ABSTRACT FROM AUTHOR]

Three thiophene- S, S-dioxidized indophenine (IDTO) isomers, 3 a ( E, E, E), 3 b ( Z, E, E), and 3 c ( Z, E, Z), were synthesized by oxidation of an indophenine compound. 3 b and 3 c could be converted into the most-stable 3 a by heating at 110 °C. An IDTO-containing conjugated polymer, PIDTOTT, was prepared using 3 a as a comonomer through a Stille coupling reaction, and it possesses a narrow band gap and low energy levels. In organic field effect transistors (OFETs), PIDTOTT exhibited unipolar n-type semiconductor characteristics with unexpectedly high electron mobility (up to 0.14 cm2 V−1 s−1), despite its rather disordered chain packing. [ABSTRACT FROM AUTHOR]

(3E,7E)-3,7-Bis(2-oxoindolin-3-ylidene)benzo[1,2-b:4,5-b′]difuran-2,6(3H,7H)-dione (IBDF) was used as a new electron-acceptor building block for polymer semiconductors with very low-lying energy levels. A copolymer of IBDF and thiophene showed stable electron transport performance in thin film transistors. [ABSTRACT FROM AUTHOR]

We report the synthesis of an aromatic amine-containing polymer ( PDPAT-12 ) and the use of this polymer as an effective additive to an ambipolar polymer semiconductor ( PIBDFBT-e37 ) to realize unipolar n-type charge transport in organic thin film transistors (OTFTs). With 10 wt% PDPAT-12 addition to PIBDFBT-e37 , the OTFTs achieved unipolar n-type charge transport with electron mobility of up to 0.42 cm 2 V −1 s −1 in nitrogen and 0.19 cm 2 V −1 s −1 in air. Moreover, the polymer blend demonstrated improved stability towards ambient air (retaining 50% of its initial electron mobility after exposed in air for 28 days) than the pristine PIBDFBT-e37 (retaining 13% of its initial electron mobility under the same conditions) and the PIBDFBT-e37 :PEI (polyethylenimine) blend, which lost transistor behaviour almost instantly once exposed to ambient air. Our results show that the use of this aromatic amine-containing polymer as an additive can convert an ambipolar polymer into an n-type unipolar polymer in OTFTs with much improved air stability. [ABSTRACT FROM AUTHOR]

In this study, we added several aromatic amine compounds as dopants to an ambipolar polymer semiconductor, PDBTAZ, and studied the charge transport behavior of the doped polymer thin films in organic thin film transistors. The trap energy ( E T ), which is the HOMO energy difference between the amine dopant and the polymer, was found related to the hole transport suppression effect of these amines. For an amine with E T < 0.25 eV, at a 2% dopant concentration, little changes in the hole transport characteristics of the doped polymer films were observed. In contrast, for an amine with E T > 0.25 eV, complete hole transport suppression was realized. This study offers a useful approach to converting an ambipolar polymer semiconductor into a unipolar n-type polymer semiconductor. [ABSTRACT FROM AUTHOR]

Highlights: [•] A p-type polymer semiconductor with exceptionally high SCLC mobility (2.3×10−2 cm2 V−1s−1) is reported. [•] Solution-processed BHJ OSCs based on this polymer and PC61BM achieved a PCE of 4.53%. [•] We demonstrate the benefits of high mobility materials as they relate to active layer thickness and fill factor. [ABSTRACT FROM AUTHOR]

Abstract: Rather consistent power conversion efficiencies have been achieved in organic solar cells throughout a wide range of active layer thicknesses (∼100nm to ∼800nm) by using a p-type polymer semiconductor with high hole transport mobility (∼1cm2 V−1 s−1) as the donor, and PC61BM as the acceptor. A comparison between standard and inverted device configurations demonstrates that the inverted configuration is more suitable for achieving thicker active layers when a high hole mobility donor is used. We attribute this to the longer hole collection path in the inverted structure, which can benefit from using a high hole mobility material. Our results will be very useful for the development of new semiconductor materials and the design of device structures for more feasible manufacturing of large area OPV devices via high speed roll-to-roll printing processes. [Copyright &y& Elsevier]