Synthesis and opto-electrical properties of stellar polyfluorene derivatives containing polyhedral oligomeric silsesquioxanes as the center core

Abstract

Three polyfluorene derivatives (P1-P3) emitting blue, green and red light were prepared via a Suzuki coupling method. Polyhedral oligomeric silsesquioxanes (POSS) were integrated into the center core of the derivatives to create stellar light-emitting polymers (POSS-P1-POSS-P3). The glass-transition and decomposition temperatures were raised after introducing POSS moieties. The starlike polymers showed a reduced emissive band at 540 nm when annealing at 200 degrees C. The result implies that integrated POSS at the center core suppresses the keto effect generally occurring for polyfluorenes. Double-layer light-emitting devices of indium tin oxide/poly(ethylenedioxythiophene)/polymer/Ca/Al were fabricated to evaluate polymer potential. Compared with pristine polymers, the maximum brightness and the current efficiency of devices using POSS-containing polymers as active layers were enhanced. A blending method using P1 or POSS-P1 as the host matrix further improved device performance.