Charge Transport Studies of Highly Stable Diketopyrrolopyrrole-Based Molecular Semiconductor

In the last decade, the diketopyrrolopyrrole (DPP)-based molecular semiconductors received significant prominence for its ability to build ambient stable donor–acceptor type organic materials for numerous microelectronics applications, especially in organic thin-film transistors and photovoltaics. This research article demonstrates the charge transport properties of 3,6-bis(5-(4-(dimethylamino)phenyl)thiophen-2-yl)-2,5-dihexadecylpyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione[DPP(PhNMe2)2] in single layer device structure prepared by thermal evaporation technique in the frequency and temperature range of 102–106 Hz and 133–273 K, respectively. An initial impression of Nyquist plot suggests metal-like behaviour as the impedance increases with an increase in temperature. Semicircle in Nyquist plot suggests Debye-type relaxation. This result has been explained mathematically and fitted equivalent circuit (contact resistance + parallel combination of resistance and capacitance) of device. Resonance frequency have been estimated by the Nyquist plot and crosschecked by Joncher’s Power Law. The frequency exponent ‘s’ is estimated by Joncher’s Universal Power Law and it further shows that charge transport mechanism in the device is quantum mechanical tunnelling. These analyses indicate the existence of Poole–Frenkel effect and explains the charge carrier mobility dependence on the applied field in the studied temperature range.