Circularly polarized deep-blue polymer light emitting diodes induced by a chiral small molecule dopant

•A solution-processable blue emitter S-F4SO has been designed and synthesized with chiral side chains.•The S-F4SO was mixed in PFO matrix to enhance CPL signal with optimized ratio and annealing temperature.•Deep blue circularly polarized light emitting diode based on the blended film exhibited a |gEL| of 4.5 × 10−3, and EL efficiency of 1.8 cd A−1 at CIE coordinate of (0.16, 0.10).