Synthesis, materials characterization and opto(electrical) properties of unsymmetrical azomethines with benzothiazole core

Optical (UV–vis and photoluminescence) properties of two soluble organic molecules based on azomethines with benzothiazole core (BTA1 and BTA2) were reported. The structures of both compounds are characterized by means FTIR, 1H NMR, and 13C NMR spectroscopy and elemental analysis; the results show an agreement with the proposed structure. The investigated compounds emitted blue light. Influence of excitation wavelength and concentration on maximum and intensity of emission of BTA1 and BTA2 was found. Electrochemical properties of the compounds were studied by differential pulse voltammetry. Introduction of fluorine moieties (BTA1) resulted in lower energy band gap (Eg) of approximately ∼0.5 eV, whereas BTA2 showed Eg of ∼2.8 eV. The devices comprised of BTA1 with P3HT:PCBM (1:1:1) showed an open circuit voltage (VOC) of 0.40 V, a short circuit current (JSC) of 1.19 mA/cm2, and a fill factor (FF) of 0.23, giving a power-conversion efficiency (PCE) of 0.10% under AM1.5G irradiation (100 mW/cm2).

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► Thiazole ring-containing azomethines were obtained.
► Blue photoluminescence exhibited both azomethines.
► The J-U effects in monolayer and BHJ devices depend on compound used.
► NMR and FTIR spectroscopy confirmed the structure of the compounds.