Correlating Charge Transport with Structure in Deconstructed Diketopyrrolopyrrole Oligomers

TY - JOUR

T1 - Correlating Charge Transport with Structure in Deconstructed Diketopyrrolopyrrole Oligomers

T2 - A Case Study of a Monomer in Field-Effect Transistors

AU - Pickett, Alec

AU - Torkkeli, Mika

AU - Mukhopadhyay, Tushita

AU - Puttaraju, Boregowda

AU - Laudari, Amrit

AU - Lauritzen, Andreas E.

AU - Bikondoa, Oier

AU - Kjelstrup-Hansen, Jakob

AU - Knaapila, Matti

AU - Patil, Satish

AU - Guha, Suchismita

PY - 2018/6/13

Y1 - 2018/6/13

N2 - 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 π-conjugated stacking direction oriented in-plane. The unit cell comprises either one monomer with a = 20.89 Å, b = 13.02 Å, c = 5.85 Å, α = 101.4°, β = 90.6°, and γ = 94.7° for one phase (TR1) or two monomers with a = 24.92 Å, b = 25.59 Å, c = 5.42 Å, α = 80.3°, β = 83.5°, and γ = 111.8° 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 cm2/V s and an on/off ratio of 106 are for films that comprise mainly the TR1 phase. GIXRD from in operando FETs demonstrates the crystalline stability of Ph-TDPP-Ph.

AB - 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 π-conjugated stacking direction oriented in-plane. The unit cell comprises either one monomer with a = 20.89 Å, b = 13.02 Å, c = 5.85 Å, α = 101.4°, β = 90.6°, and γ = 94.7° for one phase (TR1) or two monomers with a = 24.92 Å, b = 25.59 Å, c = 5.42 Å, α = 80.3°, β = 83.5°, and γ = 111.8° 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 cm2/V s and an on/off ratio of 106 are for films that comprise mainly the TR1 phase. GIXRD from in operando FETs demonstrates the crystalline stability of Ph-TDPP-Ph.

KW - charge transport

KW - conjugated molecules

KW - field-effect transistors

KW - grazing-incidence X-ray diffraction

KW - polymorphism

U2 - 10.1021/acsami.8b04711

DO - 10.1021/acsami.8b04711

M3 - Journal article

VL - 10

SP - 19844

EP - 19852

JO - A C S Applied Materials and Interfaces

JF - A C S Applied Materials and Interfaces

SN - 1944-8244

IS - 23

ER -