Blue light‐emitting diodes based on ladder polymers of the PPP type

Abstract The blue emission of ladder‐type poly( para ‐phenylene) films is unstable under heat treatment due to the formation of aggregates that emit yellow light. Novel statistical copolymers possessing ladder‐type oligo( para ‐phenylene) segments connected via twisted phenylene spacers are used to suppress the formation of these aggregates and to obtain blue emission stable under annealing.