A Solution-Processed n-Type Conducting Polymer Without Side Chains Formed via Nonmetal-Participated Polymerization and in Situ n-Doping

Solution-processed conducting polymers(CPs)are emerging as promising multifunctional materials and are motivating the development of several electronic applications.However,there are fewer highperformance electron conduction-dominated n-type CPs than p-types.Thus,the exploration of other material designs and synthesis methods is required.Accordingly,we developed a facile metal catalystfree method by combining polymerization and in situ n-doping to produce an n-type conducting polymer,poly(benzodithiophenedione)(PBTDO).The doping procedure enabled interaction between the charged conjugated backbones and solvent,dimethyl sulfoxide,making the doped conducting polymer soluble without the assistance of side chains or surfactants.PBTDO exhibited an extremely low-lying reduction level,moderate conductivity,and good air stability with potential applications in n-type organic thermoelectric devices.Moreover,it was found that the in situ doping efficiency in the reaction was highly dependent on the energy level and backbone planarity.Doping cannot occur for polymers with a high lowest unoccupied molecular orbital level and distorted conjugated chains prevent a high doping efficiency from being obtained.This study gains deeper insight into the n-doping mechanisms of conjugated polymers,with guidance for the design of highperformance n-type CPs.