Liquid-Crystalline Semiconducting Copolymers with Intramolecular Donor−Acceptor Building Blocks for High-Stability Polymer Transistors

Abstract

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. This copolymer exhibits excellent electrical characteristics such as field-effect mobilities as high as 0.33 cm(2)/V.s and good bias-stress stability comparable to that of amorphous silicon (a-Si). Liquid-crystalline thin films with structural anisotropy form spontaneously through self-organization of individual polymer chains as a result of intermolecular interactions in the liquid-crystalline mesophase. These thin films adopt preferential well-ordered intermolecular pi-pi stacking parallel to the substrate surface. This bottom-up assembly of the liquid-crystalline semiconducting copolymer enables facile fabrication of highly ordered channel layers with remarkable electrical stability.

Discotic liquid crystals of transition metal complexes 48: Synthesis of novel phthalocyanine-fullerene dyads and effect of a methoxy group on their clearing points

“…They can greatly reduce their costs to manufacture the solar cells. Liquid crystalline D-A systems are braodly classified into three groups: smectic liquid crystals [1][2][3][4], liquid crystalline copolymers [5][6][7][8][9][10][11][12] and discotic columnar liquid crystals [13][14][15][16][17][18][19][20][21][22][23][24][25]. In 2004 Kim et al reported that an organic photovoltaic cell was fabricated by using liquid crystalline N,N'-diheptyl-3,4,9,10-perylenetetracarboxylicdiimide (PTCDI-C7) as the electron acceptor and zinc phthalocyanine (ZnPc) as the electron donor [1].…”

“…Moreover, they revealed that the dyad shows a smectic A phase. Liquid crystalline donor-acceptor block copolymers have been also used for photovoltaic applications [5][6][7][8][9][10][11][12]. Morphologies of the vertically oriented mesophase of D-A separated block copolymers are very favorable for organic photovoltaics.…”

Moderate doping leads to high performance of semiconductor/insulator polymer blend transistors

“…With regard to organic field-effect transistors (OFETs), tailoring the conjugated backbone [1][2][3][4][5][6][7][8][9][10] and the side-chain architecture [11][12][13] , and optimizing the layer morphology [14][15][16][17][18][19][20] raised the performance of these materials to values comparable to that of amorphous silicon, with mobilities in excess of 0.1 cm 2 V À 1 s À 1 . However, for a widespread application of these devices, air stability and material costs are important features that need to be improved.…”

Smooth Electron Transfer from a Photoexcited Dye to Semiconductor Electrode Through a Swingable Molecular Interface

“…Photoexcited electron transfer from the immobilized molecule, tagged with the dye, to the electrode substrate is important for the fabrication of organic layer devices such as biosensors, [4][5][6] dye-sensitized solar cells, [7][8][9] and transistors. [10][11][12][13] Typically, the transfer efficiency of the photoexcited electron depends on the distance between the dye and the electrode, and the efficiency decrease with an increase in this distance. Therefore, the electron transfer efficiency form a dye immobilized through long linker molecules is very low.…”