Synthesis of blue light emitting 5-carboxylicacid-2-arylsubstituted benzimidazoles as photosensitizers for dye-sensitized solar cells

Abstract

A series of 5-Carboxylic Acid-2-Aryl substituted Benzimidazoles 3a-c, were synthesized and their Photo- physical, Electrochemical and DSSCs performance were studied. The UV-vis absorption and Photoluminescence (PL) Spectra of the compounds 3b and 3c exhibited intense deep-blue emissions with PL maximum at around 380, 382 and 400 nm (Fig. 3). Incidentally, their PL quantum yields (Φf) in solutions were found to be 0.36, 041 and 0.46 respectively. Thus, their emission spectrum displayed a broad FWHM feature extending to a longer-wavelength region, promoting the y value of the CIE resulting in a sky-blue emission of the Dyes 3a-c. Further, the good thermal stability and small FWHMs of the dyes 3a-c indicates as promising compounds for deep-blue emitters in OLEDs. The Photovoltaic performances of the Solar Cells fabricated from the prepared Electrodes under AM1.5 Solar irradiation (85 mW/cm²) are shown in Fig. 6. The Short-circuit Current Density (J_SC), Open-circuit Voltage (V_OC), Fill Factor (FF) and overall Conversion Efficiency (η) clearly reveals that the Dye 3c shows higher efficiency (2.87 %) contributed by high value of J_SC, V_OC and FF.