ALTERNATING-CURRENT LIGHT-EMITTING DEVICES BASED ON CONJUGATED POLYMERS

Most polymer electroluminescent devices to date are represented as tun nel diodes and operate under direct-current (dc) driving field. Here w e report the fabrication of symmetrically configured alternating-curre nt (ac) light-emitting (SCALE) devices based on conjugated polymers. T he new devices consist of an emissive polymer layer sandwiched between two redox polymer layers. This configuration enables the SCALE device s to work under both forward and reverse dc bias as well as in ac mode s. The nearly ohmic electrode/redox polymer contacts improve the charg e injection efficiency significantly and make the SCALE device operati on insensitive to electrode work functions. Symmetric operation suppor ts the key role of redox polymer/emissive polymer interface states. (C ) 1996 American Institute of Physics.