posted on 2023-12-12, 05:20authored byKarandeep Singh, Aiswarya Abhisek Mohapatra, Dipanjan Giri, Chandrasekhar Gangadharappa, Samik Jhulki, Stephen Barlow, Seth R. Marder, Arindam Ghosh, Satish Patil, Neha Chauhan
The realization of ambipolar (n- and p-type) doping within
a single
organic semiconductor is highly desirable for a variety of applications
but has rarely been demonstrated in solution-processed π-conjugated
polymers. This work reports ambipolar doping in donor–acceptor-based
π-conjugated naphthalenediimide-diketopyrrolopyrrole (p(gNDI-TDPP))
polymers. Optical, electrical, electron spin resonance, and photoelectron
spectroscopy measurements show evidence of the successful chemical
doping of p(gNDI-TDPP) with the n-dopant 4-(2,3-dihydro-1,3-dimethyl-1H-benzimidazol-2-yl)-N,N-dimethylbenzenamine (N-DMBI-H) as well as the related dimer (N-DMBI)2 and the p-dopant tris(4-bromophenyl)ammoniumyl hexachloroantimonate.
Temperature-dependent conductivity shows that the barrier for charge
transport is decreased at higher doping levels. We observed that the
dimer (N-DMBI)2 dopes more efficiently than N-DMBI-H as
it reacts rapidly with NDIs and can contribute two electrons per dimer
molecule. Comparable charge transport and charge-carrier concentrations
in both n- and p-doped polymers were observed. Moreover, while the
conductivity of the n-doped material drops on exposure to air, it
can be largely recovered upon annealing, indicating that air exposure
does not lead to the extensive irreversible chemical decomposition
of the doped polymer.