设计与合成了2,3-二辛基酞菁氧钒(2,3-C8OVPc),2,16(17)-二辛基酞菁氧钒(dp-C8OVPc),1,15-二辛基酞菁氧钒(1,15-C8OVPc)和1,18-二辛基酞菁氧钒(1,18-C8OVPc)4种可溶性酞菁氧钒衍生物,研究了辛基位置对该类化合物的物理化学性质、固态薄膜形貌和有机薄膜晶体管(OTFT)器件性能的影响.在溶液状态下,辛基的位置对共轭分子的吸收光谱和前线轨道能级影响很小,它们的最大吸收峰均在700 nm左右,最高被占分子轨道(HOMO)和最低未占分子轨道(LUMO)能级分别约为-5.20和-3.80 eV.在薄膜状态下,吸收光谱显著红移,且红移幅度与辛基的位置有关.4个化合物在薄膜中均以edge-on的方式排列,由它们制备的底栅-顶接触型OTFT器件的迁移率均大于0.1 cm^2/(Vs),其中2,3-C8OVPc的迁移率最高,达到0.19 cm^2/(Vs).
Solution processible organic semiconductors have attracted great attention in recent years due to their applications in printable electronics, such as organic thin-film transistor (OTFT). This type of device requires semiconductors characterized by low reorganization energies and strong intermolecular electronic interaction. Phthalocyanines are 18 π-electron disc-like aromatic macrocycles with two-dimensional (2D) n-electron delocalization over the whole molecule, and are featured with low reorganization energies and close π-π stacking. Moreover, tight 2D cofacial n-n stacking, which is beneficial for charge transport in the channel of OTFTs, can be realized by incorporating axially substituted metals or large metals in the core of phthalocyanines. Introducing alkyl substituents can endow phthalocyanines good solubility in organic solvents. However, the number and positions of alkyl substituents have great influence on the packing structures thereby OTFT performance of phthalocyanines. In the current paper, four dioctyl substituted vanadyl phthalocyanines, i.e. 2,3-dioctyl vanadyl phthalocyanine (2,3-C8OVPc), 2,16(17)-dioctyl vanadyl phthalocyanine (dp- C8OVPc), 1,15-dioctyl vanadyl phthalocyanine (1,15-C8OVPc) and 1,18-dioctyl vanadyl phthalocyanine (dp-C8OVPc), were synthesized, and the effect of the positions of octyl groups on their photophysical properties, OTFT performance was studied in detail. All four compounds are soluble in organic solvents such as chloroform and exhibit excellent thermal stability with the decomposition temperature (To) beyond 400℃. In dilute solution, the positions of octyl groups have negligible influence on their absorption spectra and frontier molecular orbital energy levels. Their absorption maxima (2max) are all at ca. 700 nm and the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energy levels are -5.2 and -3.8 eV, respectively. From solution to film, their absorption spectra exhibited