含杂原子的并五苯类似物合成及场效应性能研究

以N,N'-二苯基-1,4-苯二胺为原料, 合成了含硫和氮杂原子的并五苯类似物, 用可见-紫外吸收光谱和电化学测试对这类化合物进行表征, 确定了其光学带隙及轨道能级, 与并五苯相比它们具有低的最高占用分子轨道能级. 得到了三苯并二噻嗪的单晶结构, 分子具有平面结构, 分子间具有强的π…π相互作用和N…S相互作用. 首次将该类并五苯类似物应用于有机薄膜场效应晶体管中, 器件显示好的场效应特性, 迁移率为0.01 cm²·V^-1·s^-1.

Synthesis of Pentacene Analogues Containing Heteroatoms and Study of Their Field-effect Performance

Pentacene analogues containing nitrogen and sulfur heteroatoms were synthesized using N,N’-diphenylbenzene1,4-diamine as a starting material.Ring-closing reaction of N,N’-diphenylbenzene-1,4-diamine with sulfur powder resulted in formation of 1,4]benzothiazino2,3-b]phenothiazine(compound 1).Catalytic amounts of iodine and reflux temperature of o-dichlorobenzene were necessary.3H,10aH-1,4]Benzothiazino2,3-b]phenothiazine(compound 2) were obtained by oxidization and dehydrogenation of compound 1.The compounds 1 and 2 were purified by vacuum sublimation and characterized by UV-vis absorption spectra and cyclic voltammetry.Their optical energy gaps,energy levels of highest occupied molecular orbitals(HOMOs),and the lowest unoccupied ones were calculated.The HOMO energy levels of the compounds 1 and 2 are-5.85 and-5.42 eV,respectively.The absorption spectra of the compound 2 in thin film shows an obvious red-shift compared with that in CH2Cl2 solution,which indicates strong molecular interactions in thin film.Moreover,the crystal structure of the compound 2 was obtained and it has a planar structure.Strong π…π and N…S interactions between adjacent molecules were observed.However,there is no S…S,CH…π interactions,or hydrogen bond,which leads to no OFET performance of the compound 2.Organic field-effect transistors(OFETs) were fabricated using compound 1 as a semiconducting layer.Bottom-gate and top-contact OFET devices were fabricated by vacuum deposition on polystyrene(PS) or octadecyltrichlorosilane(OTS)-treated SiO2/Si substrates.The OFET devices fabricated on OTS-treated SiO2/Si substrates showed a good field-effect performance with a mobility of 0.01 cm2 V-1 s-1 and a current on/off ratio of 6.6×103.However,the OFET devices fabricated on the PS modified SiO2/Si substrates exhibited a lower mobility of 2.5×10-3cm2 V-1 s-1.AFM images were used to understand field-effect performance of the OFET devices fabricated on PS or OTS-treated SiO2/Si substrates.All OFET devices were tested under air.A higher field-effect performance of the pentacene analogues semiconductor could likely be achieved through proper control in functional group and device fabrication.