Acene-containing donor-acceptor conjugated polymers: Correlation between the structure of donor moiety, charge carrier mobility, and charge transport dynamics in electronic devices

We synthesized five different donor-acceptor (D-A) conjugated polymers bearing diketopyrrolopyrrole (DPP) acceptors and acene donors in the repeating groups via the Suzuki and Stille coupling methods. To investigate the effect of acene donor moieties on static and dynamic charge transport properties, pyrene, naphthodithiophene, benzodithiophene, dithieno[3,2-b:2′,3′-d] thiophene (DTT), and thieno[3,2-b]thieno[2′,3′:4,5]thieno[2,3-d] thiophene (TTTT) were selected and introduced into the structure of the polymer repeating group. Among the five polymers, the polymer PDPPTTTT bearing TTTT donor units exhibited the highest hole mobility, ∼3.2 cm² V ^-1 s^-1 (I_on/I_off > 10 ⁶) in the thin film transistors. The five polymers had different mobilities and exhibited different charge transport dynamic responses. The response was investigated by applying a pulsed bias to thin film transistors loaded with a resistor. The resistor loaded (RL) inverter made of PDPPTTTT operates well, maintaining a fairly high switching voltage ratio at a relatively high frequency. The PDPPTTTT-based RL inverter also had the fastest switching behavior with a relatively small decay time of 1.86 ms. From this study, the structure of the donor moiety in the D-A conjugated polymer was found to strongly affect the optical property, internal morphology of the polymer film, charge carrier mobility, and charge transport dynamics in electronic devices.