Dichlorinated naphthalene diimide: A high performance n-type organic semiconductor easily processed from solution as well as by sublimation in vacuum or even in air

Matthias Stolte1,  Tao He1,  Sabin-Lucian Suraru1,  Christian Burschka1,  Marcel Gsänger1,  Nis Hauke Hansen2,  Thomas Musiol3,  Daniel Kälblein3,  Ute Zschieschang4,  Jens Pflaum2,  Jochen Brill3,  Hagen Klauk4,  Frank Würthner1
1Universität Würzburg, Institut für Organische Chemie & Center for Nanosystems Chemistry, Am Hubland, 97074 Würzburg, Germany, 2Universität Würzburg, Experimental Physics VI and Bavarian Center for Applied Energy Research (ZAE Bayern e.V.), Am Hubland, 97074 Würzburg, Germany, 3InnovationLab GmbH, Speyerer Straße 4, 69115 Heidelberg, Germany and, 4Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart, Germany

Abstract

High speed organic complementary logic elements with low power consumption require not only high performance n- and p-type semiconductors but also operation in air, and easy applicable and large area processing techniques. Whereas some p-channel organic small molecules and polymers with mobilities of more than 10 cm2/Vs under ambient conditions are today known, high performance n-channel molecules with similar ability have seldom been reported. Naphthalene tetracarboxylic diimides (NDIs) with fluoroalkyl substituents are among the most promising semiconductors for n-channel organic semiconductors because of their high electron affinity.[1] Herein we report on outstanding ambient stable n-channel charge carrier mobilities of an easily accessible small molecule organic semiconductor which can be readily processed either from solution or sublimation, even in air. Two distinct polymorphs of this dichlorinated NDIs can be distinguished and are obtained either from solution or simple sublimation under ambient conditions. The morphology, thickness as well as the growth direction of small nano-crystals are investigated by SEM, AFM and TEM. The two polymorphs exhibit ambient-stable charge carrier mobilities of up to 8.6 cm2/Vs (alpha-phase)[2] and 3.5 cm2/Vs (beta-phase)[3] in single crystal field effect transistors (SCFETs), respectively. The charge transport behavior is investigated in terms of structure-property relationship. Furthermore, mobilities of about 1 cm2/Vs could be obtained for organic thin-film transistors (OTFTs) deposited on various substrates by either vacuum[4]/air sublimation[3] or solution processing techniques[5] to demonstrate the versatile applicability of this high performance material.

[1] H. E. Katz, A. J. Lovinger, J. Johnson, C. Kloc, T. Siegrist, W. Li, Y.-Y. Lin, A. Dodabalapur, Nature 2000, 404, 478-481. [2] T. He, M. Stolte, F. Würthner, Adv. Mater. 2013, 25, 6951-6955. [3] T. He, M. Stolte, C. Burschka, N. H. Hansen, T. Musiol, D. Kälblein, J. Pflaum, X. Tao, J. Brill, F. Würthner, Nat. Commun. 2015, 6, 5954. [4] J. H. Oh, S. L. Suraru, W.-Y. Lee, M. Könemann, H. W. Höffken, C. Röger,

R. Schmidt, Y. Chung, W.-C. Chen, F. Würthner, Z. Bao, Adv. Funct. Mater. 2010, 20, 2148-2156. [5] M. Stolte, M. Gsänger, R. Hofmockel, S.-L. Suraru, F. Würthner, Phys. Chem. Chem. Phys. 2012, 14, 14181-14185.