Thermally Activated n-Doping of Organic Semiconductors Achieved by N-Heterocyclic Carbene Based Dopant.

Molecular doping plays an important role in the modification of carrier density of organic semiconductors thus enhancing their optoelectronic performance. However, efficient n-doping remains challenging, especially owing to the lack of strongly reducing and air-stable n-dopants. Herein, an N-heterocyclic carbene (NHC) precursor, DMImC, is developed as a thermally activated n-dopant with the excellent stability in air. Its thermolysis in situ regenerates free NHC and subsequently dopes typical organic semiconductors. In sequentially doped FBDPPV films, DMImC does not disturb the π-π packing of the polymer and achieves good miscibility with the polymer. As a result, a high electrical conductivity of up to 8.4 S cm-1 is obtained. Additionally, the thermally activated doping and the excellent air stability permit DMImC to be noninteractively co-processed with polymers in air. Our results reveal that DMImC can be served as an efficient n-dopant suitable for various organic semiconductors.