Tuning photophysical properties of PFO conjugated polymer for enhancing polymer light emitting diode performance via addition of SiO2/TiO2 nanocomposite

Abstract

Tuning photophysical properties of poly(9,9′-di-n-octylfluorenyl-2.7-diyl) (PFO) by addition SiO2/TiO2 nanocomposites (STNCs) with different weight ratios is demonstrated. The PFO/STNCs thin films were prepared successfully by solution blending method followed by spin coating technique. The structure properties were investigated via X-ray diffraction (XRD) and field emission scanning electron microscope (FE-SEM). The optical properties were determined by using UV–Vis and photoluminescence spectrophotometer, while a Keithley 238 measurement system and HR2000 Ocean Optic Spectrometer were employed to investigate the optoelectronic properties of the PFO/STNCs based polymer light emitting diodes (PLED). The dominant phase in the PFO/STNCs thin films was for the broad hump of PFO and no variation on structure of PFO was observed upon increment the STNCs content. The aggregation of the thin films with higher STNCs content was evidenced theoretically by S-factor calculations and experimentally by FE-SEM images. The extension in the PFO conjugation length upon addition the STNCs, which plays unique role for improvement the performance of PLED devices as proved here by current density and luminance measurements, was evidenced by the systematic red shift of absorption peak of the PFO and vibronic band transitions and extended absorption tail as well.