Structurally simple OLEDs based on a new fluorinated poly(oxindolylidenearylene)

Abstract

Organic light emitting diodes (OLEDs) based on a new polymer; are reported. This new polymer; Poly[(Benzo[c] [1,2,5]thiadiazole-4,7-diylbis(9,9-dimethyl-9H-fluorene-7,2-diyl))-3,3-diyl(1-(3-(trifluoromethyl)phenyl)-2-oxindole)] (PF-2F), was used as emissive layer (EML), with a relatively simple architecture ITO/PEDOT:PSS/polymer/(LiF or PFN)/A, which is a modified version of our previously reported; PF-1: Poly[(Benzo[c] [1,2,5]thiadiazole-4,7-diylbis(9,9-dimethyl-9H-fluorene-7,2-diyl(1-phenyl-2-oxindole)], applied in OLEDs and lasing devices. The main difference between these two polymers, is the trifluoromethyl (CF3) group addition to the PF-2F. CF3 leads to improved OLEDs electroluminescence and better EQEmax; due to enhanced mechanical properties, higher solubility and higher fluorescence quantum yield (FLQY). PF-1 and PF-2F polymers have an excellent FLQY: ~1. Polymer films (by spin coating) show low roughness value (~1–2 nm), just like polymers in OLEDs. OLEDs based on the modified polymer (with yellow-green electroluminescence (EL) emission) showed luminances of up to 1937 cd/m2, current efficiencies of up to 35 cd/A and maximum external quantum efficiency (EQEmax) of up to 2.6%. Additionally, promising preliminary results on flexible OLEDs using PF-2F and PEDOT: PSS conductive (PH1000) (as anode) are reported.