Trade-off between high performance and long life due to nanofiller effects in polymer LEDs: MEH-PPV/Al2O3 nanocomposite study

This work presents the effect of nanofiller (Al2O3) in the polymer matrix MEH-PPV - Poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] on optical, optoelectronic, and electrical properties. These properties were investigated using UV–Vis absorption, and photoluminescence spectroscopy. Exciton diffusion length was examined using the surface photovoltage (SPV) method, mobility of charge carriers was evaluated with charge extraction by linearly increasing voltage (CELIV) measurements. Information concerning the band structure was obtained using energy resolved-electrochemical impedance spectroscopy (ER-EIS). The influence of nanoparticles on the development of the micro structure in thin layers was examine with grazing-incidence wide-angle X-ray scattering (GIWAXS). Prepared nanocomposite thin films were subsequently used as active layers in polymer light-emitting diodes. Luminance, current efficiency, and stability of prepared polymer light emitting diodes were tested. The presented work clarifies the effect of non-conductive nanofiller on the properties of the polymer matrix and on the performance of OLEDs with an active layer made of nanocomposite material.