Experimental and theoretical investigations on the photophysical and electronic properties of new synthesized organic small molecule for optoelectronic applications

In the present work, we report the chemical synthesis of a newly π-conjugated system using a Wittig reaction. The chemical structure of the synthesized molecule named 1,4-Bis((E)-2-(1-methyl-pyrrol-2-yl)vinyl)benzene (BisPyrBz) was supported by Fourier transform infrared spectroscopy. The optical properties were investigated first using optical absorption (O.A) and steady-state photoluminescence (PLs) tools. Otherwise, transient photoluminescence (TRPL) and quantum yield measurements (PLQY) are present in a diluted solution and condensed state. Theoretical investigations on the synthesized molecule were performed using density functional density (DFT). Experimental and theoretical data show the formation of a planar π-conjugated system. The obtained molecule presents a blue emission with high PLQY, at around 35 % in the solution state. The emission is red-shifted to the green color, with a drastic decrease of the PLQY to around 1 % indicating a possible aggregation-caused quenching behavior in the condensed state. The use of the synthesized BisPyrBz as a π linker in a newly designed A-π-D small molecule permits to obtain a newly near-infrared absorbing material with a weak energy gap Eg = ELUMO − EHOMO, which is at around 1.93 eV, and a weak optical band gap which is estimated to be 1.67 eV.