| dc.description.abstract | A specific design for solution-sheared organic semiconductors would be an effective approach to achieve high performance of organic field effect transistor (OFET) with high crystallinity and uniaxial alignment. Based on a series of thieno-isoindigo based quinoidal n-type small molecules DTPQ with alkyl-chain lengths (DTPQ-10) and different branching positions (DTPQ-b8, -b16, -b17) were developed.
The effect of the length and branching position of alkyl chains on charge transport, molecular packing and crystallinity are investigated by UV-vis spectroscopy, atomic force microscopy (AFM), grazing incidence wide angle X-ray diffraction (GIWAXD). DTPQ-b16 with branching point at two position away the backbone with longer branch length, results in high crystallinity, larger grain size and well orientation exhibit the maximum electron mobility (μe) up to 2.54 cm2 V-1 s-1, ON/OFF ratio (ION /IOFF) over than 105. In contrast, DTPQ-b8 with branching point at two position away the backbone with shorter branch length, results in poor solubility, which is disadvantage to build the lamella stacking structure, and lead to an electron mobility of 0.72 cm2 V-1 s-1. DTPQ-b17 with branching point at third position away the backbone showed obvious crack on film morphology, which are highly disadvantage to charge transport, and an electron mobilities reaching 0.192 cm2 V-1 s-1. Last, DTPQ-10 with linear alkyl chain results in poor solubility with face-on molecular packing and bad morphology exhibit the lowest electron mobility of 0.013 cm2 V-1 s-1. Especially, these four DTPQs OFETs show excellent air stability, where the devices were stored in ambient condition (room temperature; relative humidity 30~40%) for over one month. | en_US |