Electron Transport and Nanomorphology in Solution‐Processed Polymeric Semiconductor n‐Doped with an Air‐Stable Organometallic Dimer

This study investigates electron transport and distribution of an organometallic dimer-based dopant (RuCp*Mes)2 in benchmarked P(NDI2OD-T2) films, in which electron transport is not affected by deep traps originating from atmospheric contaminants. The electron mobility of P(NDI2OD-T2) can be enhanced by >10‚ in diodes with reduced thermal activation energy using (RuCp*Mes)2 dopants, which is rationalized by the filling up of tail electronic states by doping induced carriers. n-doping with (RuCp*Mes)2 can also improve electron injection at Schottky contacts in nanoscale transport measurements confirmed by conducting atomic force microscopy. The results suggest that the (RuCp*Mes)2 dopants are homogenously distributed throughout the P(NDI2OD-T2) film, at least laterally, at moderate doping concentrations. Thus, these results demonstrate an opportunity of using air-stable molecular n-doping to modulate charge transport properties for solution-processed organic optoelectronic devices.