Segregated versus Mixed Interchain Stacking in Highly Oriented Films of Naphthalene Diimide Bithiophene Copolymers
Segregated versus Mixed Interchain Stacking in Highly Oriented Films of Naphthalene Diimide Bithiophene Copolymers
复制标题
DOI：
10.1021/nn304213h
复制
发表时间：
2012-11-01
期刊：
影响因子：
17.1
通讯作者：
Sommer, Michael
中科院分区：
文献类型：
--
作者：
Brinkmann, Martin;Gonthier, Eric;Sommer, Michael
电子接受聚合物半导体聚{[N，N ′-双（2-辛基十二烷基）-1，4，5，8-萘-二甲酰亚胺-2，6-二基]-alt-5，5 '-（2，2 '-联噻吩）}（PNDI 20 D-T2），通过两种不同的方法获得，即在1，3，5-三氯苯（TCB）和摩擦转移聚（PTFE）（PTFE）衬底上的外延。通过高分辨透射电子显微镜（HRTEM）鉴定了两种具有前所未有的链内分辨率的不同多晶型。I型获得DEC TCB上，而高度取向的膜II型获得PTFE基板上的熔融后，在T=300摄氏度和冷却在05 k/min。在I型，电子衍射和HR-TEM衍射分离粘附的联噻吩（T2）和萘二酰亚胺（NDI）的单位形成单独的列。在形式II中，连续pi堆叠链之间类似于c/2的位移导致12和NDI的混合pi重叠。在两种多晶型物中NDI和T2的不同π-堆叠在紫外-可见光谱中具有特征性特征，特别是在750 nm附近的电荷转移带中，这也在旋涂膜中观察到。
Highly oriented films of an electron accepting polymer semiconductor, poly {[N,N'-bis(2-octyldodecyl)-1,4,5,8-naphthalene-dicarboximide-2,6-diyl]-alt-5,5'-(2,2'-bithiophene)} (PNDI20D-T2), are obtained by two different methods, namely directional epitaxial crystallization (DEC) on 1,3,5-trichlorobenzene (TCB) and epitaxy on friction transferred poly(tetrafluoroethylene) (PTFE) substrates. Two distinct polymorphs with unprecedented intrachain resolution are Identified by high resolution transmission electron microscopy (HRTEM). Form I is obtained DEC on TCB, whereas highly oriented films of form II are obtained on PTFE substrates after melting at T=300 degrees C and cooling at 05 k/min. In form I, both electron diffraction and HR-TEM Indicate a segregated sticking of bithiophene (T2) and naphthalene diimide (NDI) units forming separate columns. In form II, a similar to c/2 shift between successive pi-stacked chains leads to Mixed pi-overlaps of 12 and NDI. Form I can be transformed into form II by annealing at T>250 degrees C The different pi-stacking of NDI and T2 in the two polymorphs have characteristic signatures in the UV-vis spectra, especially in the charge transfer band around 750 nm which is also observed in spin-coated films.