Correlating Charge Transport with Structure in Deconstructed Diketopyrrolopyrrole Oligomers: A Case Study of a Monomer in Field-Effect Transistors

Pickett, Alec and Torkkeli, Mika and Mukhopadhyay, Tushita and Puttaraju, Boregowda and Laudari, Amrit and Lauritzen, Andreas E and Bikondoa, Oier and Kjelstrup-Hansen, Jakob and Knaapila, Matti and Patil, Satish and Guha, Suchismita (2018) Correlating Charge Transport with Structure in Deconstructed Diketopyrrolopyrrole Oligomers: A Case Study of a Monomer in Field-Effect Transistors. In: ACS APPLIED MATERIALS & INTERFACES, 10 (23). pp. 19844-19852.

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Abstract

Copolymers based on diketopyrrolopyrrole (DPP) cores have attracted a lot of attention because of their high p-type as well as n-type carrier mobilities in organic field-effect transistors (FETs) and high power conversion efficiencies in solar cell structures. We report the structural and charge transport properties of n-dialkyl side-chain-substituted thiophene DPP end-capped with a phenyl group (Ph-TDPP-Ph) monomer in FETs which were fabricated by vacuum deposition and solvent coating. Grazing-incidence X-ray diffraction (GIXRD) from bottom-gate, bottom-contact FET architectures was measured with and without biasing. Ph-TDPP-Ph reveals a polymorphic structure with pi-conjugated stacking direction oriented in-plane. The unit cell comprises either one monomer with a = 20.89 angstrom, b = 13.02 angstrom, c = 5.85 angstrom, alpha = 101.4 degrees, beta = 90.6 degrees, and gamma = 94.7 degrees for one phase (TR1) or two monomers with a = 24.92 angstrom, b = 25.59 angstrom, c = 5.42 angstrom, alpha = 80.3 degrees, beta = 83.5 degrees, and gamma = 111.8 degrees for the second phase (TR2). The TR2 phase thus signals a shift from a coplanar to herringbone orientation of the molecules. The device performance is sensitive to the ratio of the two triclinic phases found in the film. Some of the best FET performances with p-type carrier mobilities of 0.1 cm(2)/V s and an on/off ratio of 10(6)are for films that comprise mainly the TR1 phase. GIXRD from in operando FETs demonstrates the crystalline stability of Ph-TDPP-Ph.

Item Type:	Journal Article
Publication:	ACS APPLIED MATERIALS & INTERFACES
Additional Information:	Copyright of this article belong toAMER CHEMICAL SOC, 1155 16TH ST, NW, WASHINGTON, DC 20036 USA
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	16 Jul 2018 16:19
Last Modified:	16 Jul 2018 16:19
URI:	http://eprints.iisc.ac.in/id/eprint/60188

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