Introduction effects of three electron-withdrawing groups into bis-styrylbenzene skeleton on photoelectric and photophysical properties

Abstract

I synthesized three bis-styrylbenzene derivatives substituted with typical electron-withdrawing groups: E,E-1,4-bis(4-trifluoromethystyryl)benzene (CF3), E,E-1,4-bis(4-cyanostyryl)benzene (CN), and E,E-1,4-bis(4-nitrostyryl)benzene (NO2). The photophysical and photoelectrical properties of these compounds were evaluated in detail. In free molecules in the solution, the intramolecular charge transfer interaction appeared in NO2. In the solid state of CN, the intermolecular charge transfer interaction was observed in its fluorescence spectrum. On the other hand, CF3 did not show intra- and intermolecular charge transfer interactions in either the solid or solution state. The ionization potentials of CF3, CN, and NO2 were −6.52, −6.09, and −6.38 eV, respectively, suggesting that the trifluoromethyl group was most effective for decreasing ionization potentials.

A slight bluish-white fluorescence from E,E-2,6-bis(4-cyanostyryl)pyridine pristine crystals

“…The as-evaporated 4Be4CN lm showed a monomodal and wide uorescence spectrum due to its intermolecular charge transfer interaction. 26 However, the uorescence spectrum of the as-evaporated 3Be4CN lm was similar to that obtained in solution, suggesting that 3Be4CN shows no intermolecular charge transfer interaction. The absorption edges of the as-evaporated Th4CN, Py4CN and 3Be4CN lms, determined from the excitation spectra, were 517, 418, and 374 nm, respectively, and these were shied to longer wavelengths by 61, 26, and 14 nm, respectively, from the absorption edges in their solutions.…”

“…Table 2 shows that the IP values of the three compounds studied decreased in the order of Th4CN (−5.94 eV) > 3Be4CN (−6.53 eV) > Py4CN (−6.62 eV). Introduction of the CN group lowered the IP value, and thus, the IP value of 4Be4CN was −6.09 eV, 26 suggesting that the V-shaped structure of 3Be4CN is more susceptible to the effect of the CN group than the linear 4Be4CN molecule. The IP value of Py4CN was −6.62 eV, higher than that of 3Be4CN.…”

“…1 . E , E -1,4-bis(4-cyanostyryl)benzene (4Be4CN) was known 26 and also synthesised for comparison. All these three compounds are V-shaped; therefore, the linear structured compound such as 4Be4CN was necessary as a good comparison object, because the thiophene ring cannot produce a linear derivative because of its structure.…”

“…24 Recently, these compounds with various terminal substituents have been reported; their properties depend on these terminal substituents. 11,[25][26][27] Among the substituents, the introduction of a cyano (CN) group induces widening of the absorption and uorescence wavelength regions, 26 and thus, is widely used as a substituent for organic solar cell materials. 28 Additionally, it is predicted that the properties of bis-styrene derivatives will depend on the aromatic ring introduced at the central position; hence, it is essential to determine the changes introduced by each aromatic ring.…”

Improvement in thermal stability of solar cell using a non-fullerene n-type liquid crystalline semiconductor

“…The development of several π-conjugated oligomers has contributed to the advancement of organic optical and electronic devices. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] For example, bis-styrylbenzene derivatives (BSDs) and thiophene/phenylene co-oligomers (TPCOs) show remarkable optical and electrical characteristics. Various studies have reported the excellent photophysical properties of BSDs and TPCOs, where 1,4-bis(4trifluoromethylstyryl)benzene and α,ω-bis(biphenylyl) terthiophene (BP3T) show very low amplified spontaneous emission thresholds.…”