High Conductivity in Molecularly p-doped Diketopyrrolopyrrole–Based Polymer: the Impact of a High Dopant Strength and Good Structural Order

[3]-Radialene-based dopant CN6-CP studied herein, with its reduction potential of +0.8 vs Fc/Fc+ and LUMO level of -5.88 eV, is the strongest molecular p-dopant reported in open literature so far. The efficient p-doping of the donor-acceptor copolymer PDPP(6-DO)2TT having the HOMO level of -5.5 eV was achieved which confirmed by UV-vis-IR spectroscopy studies and DFT calculations. Films of PDPP(6-DO)2TT doped by CN6-CP exhibit electrical conductivities up to 50 S/cm which is one of the highest conductivity for molecularly doped semiconducting polymers. The high conductivity is attributed to a good structural order in the doped polymer as confirmed by x-ray scattering studiesdue and its high doping level. CN6-CP shows a relatively good thermal stability up to 280°C and it withstands sublimation in vacuum which makes it potentially suitable for the doping of small semiconducting molecules processed by vacuum evaporation techniques. The superior electron affinity of CN6-CP significantly broadens the range of semiconductors that can be used in devices in the p-doped state.