Photoinduced charge recombination in dipolar D–A–A photonic liquid crystal polymorphs

• DOI: 10.1039/c6cp08631d
• Publication Date: 2017-01-11T17:24:04Z
• Authors: Mercedes M. A. Mazza; Shiori Yamazaki; Dieu X. Mai; Suyog Padgaonkar; Samuel Peurifoy; Ariane Goncalves; Yi-Lin Wu; Qiaoyu Hu; Amy M. Scott
• Keywords: 02 engineering and technology; 0210 nano-technology

A hexylalkoxy dipolar D-A-A molecule [7-(4-N,N-(bis(4-hexyloxyphenyl)amino)phenyl)-2,1,3-(benzothia-diazol-4-yl)methylene]propane-dinitrile, (C6-TPA-BT-CN) has been synthesized and the photophysics studied via femtosecond transient absorption spectroscopy (FsTA) in toluene amorphous liquid crystalline spherulite thin films. Two macromolecular phases (banded, non-banded) were observed through concentration dependent, solution processing techniques are birefringent with a negative sign of elongation. dramatic change electronic from blue films to green spherulites was observed, molecular orientation determined combined analysis polarized light microscopy, X-ray diffraction, scanning electron microscopy. FsTA performed on show complex charge recombination dynamics, Stark effect, characterized TPA+˙ [BT-CN]-˙ spectroscopic signatures at 450 nm 510 identified spectroelectrochemistry. Radical cation dynamics selectively 750 >503.3 ps (18%) kinetics resulting rather significant yield free carriers consistent previous reports energetically disordered blend However, photoexcitation large, non-banded areas (>250 μm) reveal average monoexponential lifetimes 169.2 delocalized states similar those 5× longer-lived than [Chang et al., J. Am. Chem. Soc., 2013, 135, 8790] related methyl-DPAT-BT-CN whose prepared vapor deposition. Thus, correlation between microstructure film photoinduced radical pair described here is critical for developing fundamental understanding how contribute carrier energy system.