Air-Stable n-channel Diketopyrrolopyrrole-Diketopyrrolopyrrole Oligomers for High Performance Ambipolar Organic Transistors.
n-channel organic semiconductors are prone to oxidation upon exposed to ambient conditions. Herein, we report design and synthesis of diketopyrrolopyrrole (DPP)-based oligomers for ambipolar organic thin-film transistors (OFETs) with excellent air and bias stability at ambient conditions. The cyclic voltammetry measurements reveal exceptional electrochemical stability during the redox cycle of oligomers. Structural properties including aggregation, crystallinity, and morphology in thin film were investigated by UV-visible spectroscopy, atomic force microscopy (AFM), thin-film X-ray diffraction (XRD), and grazing incidence small-angle X-ray scattering (GISAXS) measurements. AFM reveals morphological changes induced by different processing conditions whereas GISAXS measurements show an increase in the population of face-on oriented crystallites in films subjected to a combination of solvent and thermal treatments. These measurements also highlight the significance of chalcogen atom from sulfur to selenium on the photophysical, optical, electronic, and solid-state properties of DPP-DPP oligomers. Charge carrier mobilities of the oligomers were investigated by fabricating top-gate bottom-contact (TG-BC) thin-film transistors by annealing the thin films under various conditions. Combined solvent and thermal annealing of DPP-DPP oligomer thin films results in consistent electron mobilities as high as ∼0.2 cm(2) V(-1) s(-1) with an on/off ratio exceeding 10(4). Field-effect behavior was retained for up to ∼4 weeks, which illustrates remarkable air and bias stability. This work paves the way toward the development of n-channel DPP-DPP-based oligomers exhibiting retention of field-effect behavior with superior stability at ambient conditions.
Solid State and Structural Chemistry Unit, Indian Institute of Science , Bangalore 560012, India.
Tushita
T
Mukhopadhyay
Solid State and Structural Chemistry Unit, Indian Institute of Science , Bangalore 560012, India.
Boregowda
B
Puttaraju
Cavendish Laboratory, Department of Physics, University of Cambridge , Cambridge CB3 0HE, United Kingdom.
Satyaprasad P
SP
Senanayak
Cavendish Laboratory, Department of Physics, University of Cambridge , Cambridge CB3 0HE, United Kingdom.
Aditya
A
Sadhanala
Cavendish Laboratory, Department of Physics, University of Cambridge , Cambridge CB3 0HE, United Kingdom.
Richard
R
Friend
Department of Physics and Centre for Plastic Electronics, Blackett Laboratory, Imperial College London , London 7W72BW, United Kingdom.
Hendrik A
HA
Faber
Department of Physics and Centre for Plastic Electronics, Blackett Laboratory, Imperial College London , London 7W72BW, United Kingdom.
Thomas D
TD
Anthopoulos
Department of Chemistry, Bilkent University , 06800 Bilkent/Ankara, Turkey.
Ulrike
U
Salzner
Institut für Physikalische Chemie, Universität Hamburg , 20148 Hamburg, Germany.
Andreas
A
Meyer
Solid State and Structural Chemistry Unit, Indian Institute of Science , Bangalore 560012, India.
Satish
S
Patil
TFT; aggregation; annealing; crystallinity; n-channel; oligomers