Photoluminescence and electroluminescence of methoxy and carboethoxy derivatives of 1,3-diphenyl-1H-pyrazolo[3,4-b]quinoline

A series of methoxy (MO) and carboethoxy (CE) derivatives of 1,3-diphenyl-1H-pyrazolo3,4-b]quinoline (DPPQ]) are characterized by spectroscopic methods. All dyes show the photoluminescent spectra which are highly solvatochromic. In the case of 6MODPPQ] and 6CEDPPQ] the emission bands are broad and shifted to the red with increasing of solvent polarity whereas the dyes 6MO1pMODPPQ] and 6MO13pMODPPQ] exhibit a reverse solvatochromism. The large difference between the excited- and state-dipole moments indicates a strong electron transfer effects in all dyes. The EL spectra are obtained for the fabricated OLEDs with a general structure of EL device ITO/PVK:6XDPPQ]/Ca/Al. The blue emission originating from PVK host matrix appears to be quenched in EL spectra of doped PVK matrix giving rise to emission in blue, blue-green or green spectral regions. The obtained results demonstrate that a series of newly synthesized methoxy and carboethoxy DPPQ]-derivatives may be considered as promising materials for electroluminescent applications.