Synthesis of the title benzo[1,2-b:4,5-bâ²]dithiophenes was achieved using 2-ethylhexyl 3,7-dihydroxybenzo[1,2-b:4,5-bâ²]dithiophene-2,6-dicarboxylate as the common starting material. The effect of the introduction of phenyl and styryl groups as well as thieno-annulation to the benzo[1,2-b:4,5-bâ²]dithiophene core on Ï-conjugation was estimated by means of absorption and emission spectrometry and cyclic voltammetry. The phase behaviours of the compounds were also observed by differential scanning calorimetry and the dithieno-annulated higher homologs were found to show a solidâsolid (crystallineâcrystalline) phase transition. Then, intrinsic charge carrier mobilities in the Ï-systems were measured by the flash-photolysis time-resolved microwave conductivity (FP-TRMC) method and the values were in the range of 0.04â0.17 cm2 Vâ1 sâ1. Remarkably, the thieno-annulated and phenyl-capped derivative showed a temperature/phase-dependent hole mobility profile with 3-fold increment in the second crystalline phase above 100 °C.
以 3,7-二羟基苯并[1,2-b:4,5-bâ²]二
噻吩-2,6-二
甲酸 2-乙基己酯为普通起始原料,合成了标题中的苯并[1,2-b:4,5-bâ²]二
噻吩。通过吸收光谱、发射光谱和循环伏安法估算了苯并[1,2-b:4,5-bâ²]二
噻吩核心引入苯基和
苯乙烯基团以及
噻吩烷化对Ï-共轭的影响。此外,还通过差示扫描量热法观察了这些化合物的相行为,发现二
噻吩annulated的高同系物出现了固-固(结晶-结晶)相变。然后,用闪烁光解时间分辨微波传导法(FP-TRMC)测量了Ï-系统中的本征电荷载流子迁移率,其值范围为 0.04â0.17 cm2 Vâ1 sâ1。值得注意的是,
噻吩annulated和苯基封端的衍
生物显示出与温度/相位相关的空穴迁移率曲线,在100°C以上的第二晶相中,空穴迁移率增加了3倍。