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Selenium in Diketopyrrolopyrrole‐based Polymers: Influence on Electronic Properties and Charge Carrier Mobilities
Author(s) -
Dhar Joydeep,
Kanimozhi Catherine,
YaccobiGross Nir,
Anthopoulos Thomas D.,
Salzner Ulrike,
Patil Satish
Publication year - 2014
Publication title -
israel journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.908
H-Index - 54
eISSN - 1869-5868
pISSN - 0021-2148
DOI - 10.1002/ijch.201400051
Subject(s) - ambipolar diffusion , chemistry , charge carrier , band gap , thiophene , polymer , electron mobility , organic semiconductor , chemical physics , conjugated system , electron , optoelectronics , materials science , organic chemistry , physics , quantum mechanics
Diketopyrrolopyrrole (DPP)‐based π‐conjugated copolymers with thiophene have exceptionally high electron mobilities. This paper investigates electronic properties and charge carrier mobilities of selenophene containing analogues. Two new copolymers, with alternating thiophene DPP (TDPP) and selenophene DPP (SeDPP) units, were synthesized. Two side‐chains, hexyl (Hex) and triethylene glycol (TEG) were employed, yielding polymers designated as PTDPPSeDPP‐Hex and PTDPPSeDPP‐TEG. Selenophene systems have smaller band gaps, with concomitant enhancement of the stability of the reduced state. For both polymers, ambipolar mobilities were observed in organic field‐effect transistors (OFET). Grazing incidence X‐ray diffraction (GIXD) data indicates preferential edge‐on orientation of PTDPPSeDPP‐TEG, which leads to superior charge transport properties of the TEG substituted polymer, as compared to its Hex analogue. Time‐dependent‐density functional theory (TDDFT) calculations corroborate the decrease in the optical band gap with the inclusion of selenophene. Ambipolar charge transport is rationalized by exceptionally wide conduction bands. ΔSCF calculations confirm the larger electron affinity, and therefore the greater stability, of the reduced form of the selenophene‐containing DPP polymer in presence of chloroform.