Homoleptic iridium complexes with dibenzothiophene sulfone and triphenylamine groups for orange polymer light-emitting diodes

Abstract

We have designed and synthesized two new orange light-emitting homoleptic iridium complexes ((p-FSOPyTPA)3Ir and (m-FSOPyTPA)3Ir) containing dibenzothiophene sulfone and triphenylamine frameworks. Solution-processed polymer light-emitting devices (PLEDs) are also prepared using these as-synthesized iridium complexes with a single-emission-layer (SEL) structure of ITO/PEDOT:PSS/poly-TPD/EML/TPBI/Ba/Al. Both the iridium complexes exhibited good thermal stability with a Td > 430 °C. Compared to (p-FSOPyTPA)3Ir, (m-FSOPyTPA)3Ir displayed much better thermal, photophyscial and electroluminescent properties owing to the different coordinate positions of dibenzothiophene sulfone. More importantly, the orange-emitting PLEDs based on (m-FSOPyTPA)3Ir exhibited a maximum luminous efficiency (LE) of 4.65 cd/A, a maximum external quantum efficiency (EQE) of 2.03%, and the Commission Internationale de L'Eclairage (CIE) coordinates of (0.54, 0.42), when the iridium complex doped into a matrix of PVK/OXD-7 with a concentration of 4 wt %. Our preliminary work could provide a promising orange emitters candidate for the development of solution-processable highly efficient white PLEDs.