Luzio Alessandro, Nübling Fritz, Martin Jaime, Fazzi Daniele, Selter Philipp, Gann Eliot, McNeill Christopher R, Brinkmann Martin, Hansen Michael Ryan, Stingelin Natalie, Sommer Michael, Caironi Mario
Center for Nano Science and Technology@PoliMi, Istituto Italiano di Tecnologia, via Giovanni Pascoli 70/3, Milan, 20133, Italy.
Technische Universität Chemnitz, Polymerchemie, Straße der Nationen 62, 09111, Chemnitz, Germany.
Nat Commun. 2019 Jul 29;10(1):3365. doi: 10.1038/s41467-019-11125-9.
Recent demonstrations of inverted thermal activation of charge mobility in polymer field-effect transistors have excited the interest in transport regimes not limited by thermal barriers. However, rationalization of the limiting factors to access such regimes is still lacking. An improved understanding in this area is critical for development of new materials, establishing processing guidelines, and broadening of the range of applications. Here we show that precise processing of a diketopyrrolopyrrole-tetrafluorobenzene-based electron transporting copolymer results in single crystal-like and voltage-independent mobility with vanishing activation energy above 280 K. Key factors are uniaxial chain alignment and thermal annealing at temperatures within the melting endotherm of films. Experimental and computational evidences converge toward a picture of electrons being delocalized within crystalline domains of increased size. Residual energy barriers introduced by disordered regions are bypassed in the direction of molecular alignment by a more efficient interconnection of the ordered domains following the annealing process.
最近在聚合物场效应晶体管中电荷迁移率的反向热激活现象激发了人们对不受热垒限制的输运机制的兴趣。然而，对于进入此类机制的限制因素仍缺乏合理的解释。深入了解这一领域对于新材料的开发、制定加工指南以及拓宽应用范围至关重要。在此我们表明，对基于二酮吡咯并吡咯 - 四氟苯的电子传输共聚物进行精确加工，可得到单晶状且与电压无关的迁移率，在280 K以上激活能消失。关键因素是单轴链排列以及在薄膜熔化吸热范围内的温度下进行热退火。实验和计算证据都指向电子在尺寸增大的结晶域内离域的图景。无序区域引入的残余能垒在退火过程后通过有序域更有效的相互连接，在分子排列方向上被绕过。
