Kim Choongik, Facchetti Antonio, Marks Tobin J
Department of Chemistry and the Materials Research Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, USA.
J Am Chem Soc. 2009 Jul 1;131(25):9122-32. doi: 10.1021/ja902788z.
Organic semiconductor-based thin-film transistors (TFTs) have been extensively studied for organic electronics. In this study, we report on the influence of the polymer gate dielectric viscoelastic properties on overlying organic semiconductor film growth, film microstructure, and TFT response. From the knowledge that nanoscopically-confined thin polymer films exhibit glass-transition temperatures that deviate substantially from those of the corresponding bulk materials, we show here that pentacene (p-channel) and cyanoperylene (n-channel) films grown on polymeric gate dielectrics at temperatures well-below their bulk glass transition temperatures [T(g)(b)] exhibit morphological/microstructural transitions and dramatic OTFT performance discontinuities at well-defined temperatures [associated with a polymer "surface glass transition temperature," or T(g)(s)]. These transitions are characteristic of the particular polymer architecture and independent of film thickness or overall film cooperative chain dynamics. Our results demonstrate that TFT measurements represent a new and sensitive methodology to probe polymer surface viscoelastic properties.
基于有机半导体的薄膜晶体管（TFT）已在有机电子学领域得到广泛研究。在本研究中，我们报告了聚合物栅极介质的粘弹性性质对其上覆有机半导体膜生长、膜微观结构和TFT响应的影响。基于纳米尺度受限的聚合物薄膜表现出与相应块状材料的玻璃化转变温度有显著偏差这一认识，我们在此表明，在远低于其块状玻璃化转变温度[T(g)(b)]的温度下，生长在聚合物栅极介质上的并五苯（p沟道）和氰基苝（n沟道）膜，在明确的温度下[与聚合物“表面玻璃化转变温度”或T(g)(s)相关]呈现出形态/微观结构转变以及显著的有机薄膜晶体管（OTFT）性能不连续性。这些转变是特定聚合物结构的特征，且与膜厚度或整个膜的协同链动力学无关。我们的结果表明，TFT测量代表了一种探测聚合物表面粘弹性性质的新型灵敏方法。
