Chabinyc Michael L, Toney Michael F, Kline R Joseph, McCulloch Iain, Heeney Martin
Palo Alto Research Center, Palo Alto, California 94304, USA.
J Am Chem Soc. 2007 Mar 21;129(11):3226-37. doi: 10.1021/ja0670714. Epub 2007 Feb 22.
Poly(2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b]thiophene), PBTTT, is a semiconducting polymer that forms thin film transistors (TFTs) with high field effect mobility on silicon dioxide dielectrics that are treated with alkyltrichlorosilanes ( approximately 0.2 to 0.5 cm2/V s) but forms TFTs with poor mobility on bare silicon dioxide (<0.005 cm2/V s). The microstructure of spin-coated thin films of PBTTT on these surfaces was studied using synchrotron X-ray diffraction and atomic force microscopy. PBTTT crystallizes with lamellae of pi-stacked polymer chains on both surfaces. The crystalline domains are well-oriented relative to the substrate in the as-spun state and become highly oriented and more ordered with thermal annealing in the liquid crystalline mesophase. Although the X-ray scattering from PBTTT is nearly identical on both surfaces, atomic force microscopy showed that the domain size of the crystalline regions depends on the substrate surface. These results suggest that electrical transport in PBTTT films is strongly affected by the domain size of the crystalline regions and the disordered regions between them.
聚（2,5-双（3-烷基噻吩-2-基）噻吩并[3,2-b]噻吩），PBTTT，是一种半导体聚合物，它在经烷基三氯硅烷处理的二氧化硅电介质上形成具有高场效应迁移率的薄膜晶体管（TFT）（约0.2至0.5平方厘米/伏·秒），但在裸二氧化硅上形成的TFT迁移率较差（<0.005平方厘米/伏·秒）。使用同步加速器X射线衍射和原子力显微镜研究了PBTTT在这些表面上旋涂薄膜的微观结构。PBTTT在两个表面上都以π-堆积聚合物链的片晶形式结晶。在初纺状态下，晶域相对于基底取向良好，并且在液晶中间相中通过热退火变得高度取向且更加有序。尽管PBTTT在两个表面上的X射线散射几乎相同，但原子力显微镜显示结晶区域的畴尺寸取决于基底表面。这些结果表明，PBTTT薄膜中的电传输受到结晶区域的畴尺寸及其之间无序区域的强烈影响。
