Light-triggered regionally controlled n-doping of organic semiconductors

Abstract

Doping is a primary method to modulate the electrical properties of semiconductors, enabling the fabrication of various homojunctions/heterojunctions and complex devices^{1,2,3,4,5,6,7,8}. For organic semiconductors (OSCs), the electrical performance has been extensively improved by developing doping methods and dopants^{9,10,11,12,13}. However, compared with the state-of-the-art spatial resolution of inorganic semiconductor fabrication processes, OSCs lag far behind, limiting the construction of complex organic electronic devices⁵. Here we present a facile light-triggered doping strategy and develop a series of inactive photoactivable dopants (iPADs) for regionally controlled n-doping of OSCs. By converting iPADs into active dopants through ultraviolet (UV) exposure, controllable doping of various n-type OSCs with high electrical conductivity greater than 30 S cm⁻¹ has been realized. Using iPADs can substantially improve the performances of OSCs in transistors, logic circuits and thermoelectrics. Also, regionally controlled doping is demonstrated in OSCs with a record resolution down to 1 μm. Overall, our strategy has achieved tunable doping levels in OSCs with high spatial resolution, which is expected to be highly suited for integrated circuits in both roll-to-roll and laboratory-scale environments.