6H-Pyrrolo[3,2-b:4,5-b′]bis[1,4]benzothiazines: facilely synthesized semiconductors for organic field-effect transistors

Abstract

6H-Pyrrolo[3,2-b:4,5-b 0 ]bis [1,4]benzothiazine (PBBTZ, 1) and its two 6-substituted derivatives (2 and 3) were conveniently synthesized. Their optical properties were studied by UV-vis and fluorescence spectroscopy, and electrochemical properties were investigated by cyclic voltammetry (CV). Good thermal stability was observed by thermogravimetric analysis. X-Ray analysis revealed a coplanar structure and a column stacking in the single crystal of compound 1. OFET measurements showed that 1-3 were p-type semiconductors. The performance of these devices displayed good reproducibility at ambient conditions. When devices containing 1 were fabricated on OTS-treated SiO 2 /Si substrates at 60 C, the best performance was achieved with the average hole mobility as high as 0.34 cm 2 V À1 s À1 and the on/off ratio about 10 6 -10 7 . This performance resulted from the well-ordered molecular packing as revealed by XRD and AFM analysis.Scheme 1 Synthesis of 6-substituted PBBTZ (1-3).

Organic Single Crystal Field‐effect Transistors Based on 6H‐pyrrolo[3,2–b:4,5–b´]bis[1,4]benzothiazine and its Derivatives

“…Growth of the Single Crystals and Device Fabrication: PBBTZ 1-3 were synthesized as previously described [23] and purified by gradient sublimation twice before use as the source materials for the growth of single crystals. PBBTZ 1-3 single crystalline ribbons were grown by physical vapor transport processes in a horizontal tube furnace as reported [24].…”

“…[7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] Recently, we reported the thin film transistors based on a pentacene analogue: 6H-pyrrolo-[3,2-b:4,5-b]bis [1,4]benzothiazine and its 6-substituted derivatives (PBBTZ 1-3, see Scheme 1). [23] A high mobility up to 0.35 cm 2 V À1 s À1 and an on/off ratio of around 1.5 Â 10 7 have been obtained from the devices of 1. Moreover, these materials also display other advantages such as facile synthesis and increased stability compared with that of pentacene.…”

“…The highest mobilites of the SCFETs were 10, 80, and 130 times higher than those of the thin film devices of 1, 2, and 3, respectively. [23] Based on the individual single-crystalline ribbons of 1-3, a total of 100 SCFET devices were fabricated and examined. Their performance data, including field-effect mobility (m), on/off current ratio (I on /I off ), and threshold voltage (V T ) are summarized in Table 1.…”

Synthesis and Properties of Heteroacenes Containing Pyrrole and Thiazine Rings as Promising n‐Type Organic Semiconductor Candidates

“…The hydrochloride 1 could be effectively neutralized in the solvent acetic acid by action with one equivalent of anhydrous sodium acetate, affording the free base 2-amino-4-(trifluoromethyl)benzenethiol and the inert byproduct sodium chloride. The one-pot Scheme 1 Synthesis of PBBTZ derivatives 3a and 3b condensation in refluxing solvent with N-functionalized 2, 3-dichloromaleimides 2a and 2b which were obtained according to the literature, 7,12 gave the target compounds 3a and 3b in 43% and 46% yields, respectively. Compound 3a was almost indissolvable in the reaction system and easily separated by filtration.…”

“…2,3 Recently, we have reported a heteroacene PBBTZ (6H-pyrrolo [3,2-b:4,5-b']bis [1,4]benzothiazine) with high p-type OFET activity and environmental stability. 7 It possesses a rigid, linear, coplanar conjugated structure similar to that of the most famous p-type semiconductor pentacene, and yet there is no unit in this molecule being capable of a photo-induced decomposition. We also realized that π-conjugated molecules modified by electron-withdrawing groups could be changed into air-stable n-type materials.…”