title: Vapor-phase transport deposition, characterization, and applications of large nanographenes.
abstract: Recently, chemical synthesis of a range of large nanographene molecules with various shapes and sizes opened a new path to utilize them in various applications and devices. However, due to their extended aromatic cores and high molecular weight, film formation of large nanographene molecules, bearing more than 90 sp(2) carbon atoms in aromatic cores, is very challenging, which has prevented their applications such as in thin-film transistors. Here, we developed an effective approach to prepare films of such large nanographene molecules using a vapor-phase transport (VPT) technique based on molecule sublimation. The VPT of these molecules was made possible by combining the molecules and the target substrate in a small confinement of vacuum-sealed glass tube, so that a small amount of sublimation can be utilized to create films. Surprisingly, such heavy and large molecules can be deposited on any substrate by this method to create films of assembled large nanographene molecules while maintaining their aromatic cores intact, which was confirmed using mass spectrometry measurements. Moreover, field-effect transistors based on these films are depleted and show significantly improved current on/off ratio compared to previous large nanographene-based transistors fabricated using liquid-phase-based process. Our work shows that VPT deposition can be a viable technique to prepare films based on large nanographene molecules and potentially other high molecular weight compounds, which may find exciting applications in electronics and optoelectronics.
authors.affiliation: ‡Department of Electrical Engineering, University of Southern California, Los Angeles, California 90089, United States.|∥Department of Electrical Engineering, University of Jeddah, Abdullah Sulayman St, Jeddah 22254, Saudi Arabia.
authors.forename: Ahmad N
authors.initials: AN
authors.lastname: Abbas
authors.affiliation: ‡Department of Electrical Engineering, University of Southern California, Los Angeles, California 90089, United States.
authors.forename: Bilu
authors.initials: B
authors.lastname: Liu
authors.affiliation: §Max Planck Institute of Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
authors.forename: Akimitsu
authors.initials: A
authors.lastname: Narita
authors.affiliation: §Max Planck Institute of Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
authors.forename: Lukas F
authors.initials: LF
authors.lastname: Dössel
authors.affiliation: §Max Planck Institute of Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
authors.forename: Bo
authors.initials: B
authors.lastname: Yang
authors.affiliation: §Max Planck Institute of Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
authors.forename: Wen
authors.initials: W
authors.lastname: Zhang
authors.affiliation: †Device Research Laboratory, Department of Electrical Engineering, University of California, Los Angeles, California 90095, United States.
authors.forename: Jianshi
authors.initials: J
authors.lastname: Tang
authors.affiliation: †Device Research Laboratory, Department of Electrical Engineering, University of California, Los Angeles, California 90095, United States.
authors.forename: Kang L
authors.initials: KL
authors.lastname: Wang
authors.affiliation: §Max Planck Institute of Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
authors.forename: Hans Joachim
authors.initials: HJ
authors.lastname: Räder
authors.affiliation: §Max Planck Institute of Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
authors.forename: Xinliang
authors.initials: X
authors.lastname: Feng
authors.affiliation: §Max Planck Institute of Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
authors.forename: Klaus
authors.initials: K
authors.lastname: Müllen
authors.affiliation: ‡Department of Electrical Engineering, University of Southern California, Los Angeles, California 90089, United States.
authors.forename: Chongwu
authors.initials: C
authors.lastname: Zhou