Contents lists available at ScienceDirect Synthetic Metals journal homepage: www.elsevier.com/locate/synmet The role of surface morphology in a performance of top-gate OFETs prepared from a solution processable derivative of perylene bisimide Magdalena Kucinska a , Izabela Frac a , Jacek Ulanski a, ⁎ , Tomasz Makowski b , Andrzej Nosal c , Maciej Gazicki-Lipman c a Department of Molecular Physics, Lodz University of Technology, Zeromskiego 116, 90-924, Lodz, Poland b Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, 90-363, Lodz, Poland c Institute of Materials Science and Engineering, Lodz University of Technology, Stefanowskiego 1/15, 90-924, Lodz, Poland ARTICLE INFO Keywords: n-Channel organic field-effect transistors Spin-coated perylene derivative Surface morphology Parylene C ABSTRACT A commercially available, soluble in chlorinated hydrocarbons perylene derivative, N,N-bis(1-ethylpropyl)- perylene-3,4:9,10-bis(dicarboximide) (PTCDI-C5(3)), was used to construct n-channel organic field effect tran- sistors (OFETs). The transistors had the top-gate-bottom-contacts (TGBC) architecture, with a spin-coated layer of the active material. This material was subsequently coated with Parylene C gate dielectric layer which, to- gether with a silver gate electrode deposited on the top of that layer, provided a protection of the device against the water and oxygen molecules. In order to investigate the effect of the morphology of semiconductor/gate dielectric interface on the device parameters, a series of OFETs with PTCDI-C5(3) layers spin-coated at different spinning rates were prepared. Three chlorinated hydrocarbon solvents with different boiling points were used: chloroform, chlorobenzene and 1,2-dichlorobenzene. The resulting polycrystalline layers of perylene derivative differed with regard to their thickness and to their roughness as well as exhibited different grains size and shape. Surprisingly however, no direct correlation between the transistor parameters and the thickness of the semi- conductor layer or the roughness of the semiconductor/dielectric interface was found – in fact the worst per- formance was recorded for the OFETs with PTCDI-C5(3) layers of the lowest roughness, spin-coated from chloroform. 1. Introduction A prospective advantage of organic electronics - not materialized yet - is comprised of a potential to employ, for a production of elec- tronic devices, some simple and inexpensive solution based techniques [1], preferably printing [2,3]. In most of these devices, the principal building elements are made of complementary circuits containing pairs of field-effect transistors with both p-type and n-type channels ex- hibiting symmetrical characteristics and comparable parameters. As far as organic field-effect transistors (OFETs) are concerned, in contrast to numerous realizations of a p-type channel transistor, only a few high performance OFETs made of solution processable n-type semi- conductors are described in the literature, see e.g.[4–6]. This limitation appears to constitute a major obstacle in the development of printed organic electronics, especially in the case of open air operating OFETs, where n-channel transistors typically show poor stability due to their high sensitivity to water and oxygen molecules [7]. For an n-type semiconductor, the electron affinity must be high enough to enable electron injection from the electrode into the LUMO level. Nitrogen substituted bisimide derivatives of large core conjugated hydrocarbon systems such as perylene (PTCDIs), seem to be well suited for that purpose. They are characterized by a relatively high electron affinity, good charge transport properties, high chemical, thermal, and photochemical stability as well as high electron mobility. Furthermore, PTCDIs possess a capacity to self-assembly into highly ordered one-di- mensional columnar stacks with a good intermolecular π-π overlap [8,9]. Making use of these advantages, Ramesh et al. constructed transistors based on PTCDI–C8 thermally evaporated onto a dielectric CYTOP film, which were reported stable under an atmospheric condi- tion for at least 2000 h [10]. As generally promising candidates for n-type organic semi- conductors, perylene derivatives are characterized by one major set- back. Due to a strong interaction between aromatic cores originating from their π-stacking, they are poorly soluble. This is a reason why the majority of literature reports in this area concern devices prepared with the help of the vacuum evaporation technique [10,11]. On the other https://doi.org/10.1016/j.synthmet.2019.02.008 Received 20 November 2018; Received in revised form 16 February 2019; Accepted 16 February 2019 ⁎ Corresponding author. E-mail address: jacek.ulanski@p.lodz.pl (J. Ulanski). Synthetic Metals 250 (2019) 12–19 0379-6779/ © 2019 Elsevier B.V. All rights reserved. T