Donor-pi-acceptor type fluorene-based copolymers with a sulfone unit were designed and synthesized for application in efficient pure-blue light emitting. The electroluminescence behaviors of these copolymers were investigated by fabricating light-emitting diodes and electrochemical cell devices. The former device little functioned but the latter worked well. The electrochemical cell devices having a configuration of ITO/PEDOT: PSS/copolymer: ionic liquid/Al exhibited purplish blue electroluminescence with an emission maximum at 434 nm (CIE coordinates (x, y) 5(0.17, 0.10)) measured at 7 V. The initial positive scan of the D-pi-A polysulfone based light emitting electrochemical cell with a sweep rate of 0.1 V s(-1) afforded a maximum luminance of 1080 cd m(-2) with a current efficiency of 1.96 cd A(-1) at an operating voltage of 12.5 V. (C) 2016 Wiley Periodicals, Inc.