White Light-Emitting Devices Based on Star-Shape Polymers with a Bisindolylmaleimide Core

A new type of star-shape polymers employing bisindolylmaleimide dye (2a-c) as the core and poly(2,7-fluorene) (PO and/or poly(2,7-carbazole) (PC) as the arms were synthesized These materials exhibited dual emissions consisting of an intensive blue luminescence from PF or PC and an orange emission from maleimide a result of partial energy transfer between the two. Highly efficient white light emitting devices were fabricated using a single emitting film made by spin-coating method The electroluminescence (EL) properties of the devices were investigated from several directions, such as the loading amount of maleimide core, the concern ration dependent spectral changes. the difference in the composition of arms, and the substituent effect in the indole segment. etc A typical device based on the star-shape polymer MF001 containing 0 01 mol% of core exhibited a maximal luminous efficiency of 7 2 cd/A and external quantum efficiency of 32% The device based on MMF0001 with a methyl substituent on the indole group can be improved to reaching a maximal brightness of 11450 cd/m(2), and that based on MFC1001 with aims comprising equal amount of PF and PC can be boosted to a maximal power efficiency 014 8 lm/w All devices can lie la limited readily and turned on at a considerable low voltage (<5 v)