Majority carrier type conversion in solution-processed organic transistors and flexible complementary logic circuits

Abstract

We report on the realization of high performance solution-processed ambipolar organic transistors based on a quinoidal oligothiophene derivative. The devices show hole and electron field-effect mobilities in air as high as 0.1 and 0.006 cm2 V−1 s−1, respectively, and can be converted from ambipolar p-type dominant to n-type transistors by thermal annealing. The conversion of the majority carrier type is assigned to strong variations in molecular packing. The demonstration of complementary flexible inverters suggests an effective strategy for patterning lateral pn-bipolar structures in solution-processed thin films made from a monolithic ambipolar organic semiconductor.

Non-volatile organic memory with sub-millimetre bending radius

“…In addition, no particular epitaxial crystallization could be seen on the PVDF-TrFE, meaning that the crystalline structure of the QQT(CN)4 thin films prepared on either PVDF-TrFE or SiO 2 (ref. 43) is similar. Crystal structure of powdered QQT(CN)4 in a triclinic system was revealed by powder X-ray experiment with help of simulated X-ray pattern analysis ( Supplementary Fig.…”

“…The surface morphology of this sample is similar to that previously observed in QQT(CN)4 films spin-coated onto SiO 2 (ref. 43). The devices fabricated on polyimide (PI) substrates are indeed extremely flexible and rollable without delamination of the components or mechanical crack formation as shown in Fig.…”

“…As-prepared p-type and annealed n-type organic QQT(CN)4 FETs were previously found to exhibit hole and electron mobilities as high as 0.1 and 0.015 cm 2 V À 1 s À 1 , respectively (Supplementary Fig. 1) [43][44][45] . These mobility values are high enough to realize ferroelectric polymer memory devices in both p-and n-type modes.…”

“…The solution-processed Fe-FETs with ferroelectric poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE) and semiconducting dicyanomethylene-substituted quinoidal quaterthiophene derivative (QQT(CN)4) exhibited p-type and n-type current hysteresis, which arises from majority carrier type conversion induced in QQT(CN)4 by a simple thermal annealing treatment [43][44][45] . In both switching modes, the memory device shows outstanding mechanical flexibility.…”

Patterning of Cu thin films on layer-by-layer films of anionic polymer and TiO₂ nanoparticles on plastic sheets

“…[23,24] We have reported the fabrication methods of functional nanomaterial films on plastic sheets from the viewpoints of increasing operating lifetime of emitting layers and of reducing material consumption and fabrication steps. [25][26][27][28] In this study, we discuss a technique for the direct patterning of Cu thin films using electroless deposition on Pd nanoparticles photodeposited on the LbL films consisting of sodium polystyrene sulfate (PSS) and TiO 2 nanoparticles. The LbL films were formed on glass plates and plastic sheets by alternate soaking in acidic solution of PSS and TiO 2 nanoparticle dispersion.…”