Lee Kyu Cheol, Park Won-Tae, Noh Yong-Young, Yang Changduk
School of Energy and Chemical Engineering, KIER-UNIST Advanced Center for Energy, Low Dimensional Carbon Materials Center, Ulsan National Institute of Science and Technology (UNIST) , Banyeon-ri 100, Eonyang-eup, Ulju-gun, Ulsan, 689-798 South Gyeongsang, South Korea.
ACS Appl Mater Interfaces. 2014 Apr 9;6(7):4872-82. doi: 10.1021/am405917a. Epub 2014 Mar 24.
In order to determine the effects of actual 'chalcogen atoms' on semiconducting properties for application in a variety of optoelectronic devices, a class of donor (D)-acceptor (A) polymer semiconductors, namely PBDP-Fu, PBDP-Th, and PBDP-Se, containing the recently formulated benzodipyrrolidone (BDP) accepting unit and furan (Fu), thiophene (Th), or selenophene (Se) as a donating unit has been synthesized, characterized, and used in an active layer of organic field-effect transistors (OFETs). With the LUMO levels being comparatively consistent for all three polymers (-3.58 to -3.60 eV) due to the dominant BDP contribution to the polymer backbone, the HOMO energies are somewhat sensitive to the structurally distinctive feature of the donor counits used. Utilizing a combination of X-ray diffraction (XRD) and atomic force microscopy (AFM), it is apparent that further crystalline domains occur with edge-on orientation for the polymers (PBDP-Th and PBDP-Se) with relatively heavier chalcogen atoms such as Th and Se, compared with PBDP-Fu which has a rather amorphous nature. Investigation of their OFET performance indicates that all the polymers show well balanced ambipolar operations. The desirable morphological structures of both the PBDP-Th and PBDP-Se result in higher mobilities in OFETs than those of PBDP-Fu. In particular, 200 °C annealed PBDP-Se OFETs results in ambipolarity being mobile for both holes of up to 1.7 × 10(-2) cm(2)/V·s and electrodes of up to 1.9 × 10(-2) cm(2)/V·s. In addition, OFETs with PBDP-Th show nearly equivalent charge carrier mobilities for both holes (μ(h) = 1.2 × 10(-2) cm(2)/V·s) and electrons (μ(e) = 1.1 × 10(-2) cm(2)/V·s). Consequently, we systematically demonstrate how the manipulation of existing heteroaromatics can modulate the electronic properties of conjugated D-A polymers, elucidating structure-property relationships that are desirable for the rational design of next generation materials.
为了确定实际的“硫族原子”对各种光电器件应用中半导体性能的影响，一类供体（D）-受体（A）聚合物半导体，即含有最近配制的苯并二吡咯烷酮（BDP）接受单元以及呋喃（Fu）、噻吩（Th）或硒吩（Se）作为供体单元的PBDP-Fu、PBDP-Th和PBDP-Se，已被合成、表征并用于有机场效应晶体管（OFET）的有源层。由于BDP对聚合物主链的主要贡献，这三种聚合物的最低未占分子轨道（LUMO）能级相对一致（-3.58至-3.60 eV），而最高已占分子轨道（HOMO）能量对所用供体共单元的结构独特特征有些敏感。利用X射线衍射（XRD）和原子力显微镜（AFM）相结合的方法，可以明显看出，与具有相当无定形性质的PBDP-Fu相比，含有相对较重硫族原子（如Th和Se）的聚合物（PBDP-Th和PBDP-Se）会出现更多边缘取向的结晶域。对它们的OFET性能进行研究表明，所有聚合物都表现出良好的平衡双极性操作。PBDP-Th和PBDP-Se理想的形态结构导致它们在OFET中的迁移率高于PBDP-Fu。特别是，在200℃退火的PBDP-Se OFET中，空穴的双极性迁移率高达1.7×10⁻² cm²/V·s，电子的双极性迁移率高达1.9×10⁻² cm²/V·s。此外，具有PBDP-Th的OFET对空穴（μ(h)=1.2×10⁻² cm²/V·s）和电子（μ(e)=1.1×10⁻² cm²/V·s）显示出几乎相等的电荷载流子迁移率。因此，我们系统地展示了如何通过对现有杂芳烃的调控来调节共轭供体-受体（D-A）聚合物的电子性质，阐明了对下一代材料进行合理设计所需的结构-性能关系。
