title: Surface functionalization of two-dimensional metal chalcogenides by Lewis acid-base chemistry.
abstract: Precise control of the electronic surface states of two-dimensional (2D) materials could improve their versatility and widen their applicability in electronics and sensing. To this end, chemical surface functionalization has been used to adjust the electronic properties of 2D materials. So far, however, chemical functionalization has relied on lattice defects and physisorption methods that inevitably modify the topological characteristics of the atomic layers. Here we make use of the lone pair electrons found in most of 2D metal chalcogenides and report a functionalization method via a Lewis acid-base reaction that does not alter the host structure. Atomic layers of n-type InSe react with Ti(4+) to form planar p-type [Ti(4+)n(InSe)] coordination complexes. Using this strategy, we fabricate planar p-n junctions on 2D InSe with improved rectification and photovoltaic properties, without requiring heterostructure growth procedures or device fabrication processes. We also show that this functionalization approach works with other Lewis acids (such as B(3+), Al(3+) and Sn(4+)) and can be applied to other 2D materials (for example MoS2, MoSe2). Finally, we show that it is possible to use Lewis acid-base chemistry as a bridge to connect molecules to 2D atomic layers and fabricate a proof-of-principle dye-sensitized photosensing device.
authors.affiliation: Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, USA.
authors.forename: Sidong
authors.initials: S
authors.lastname: Lei
authors.affiliation: Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, USA.
authors.forename: Xifan
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, USA.
authors.forename: Bo
authors.identifier: 0000-0001-9766-7925
authors.initials: B
authors.lastname: Li
authors.affiliation: Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106, USA.
authors.forename: Jiahao
authors.initials: J
authors.lastname: Kang
authors.affiliation: Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, USA.|School of Physical Science and Technology, Lanzhou University, Lanzhou, Gansu 730000, China.
authors.forename: Yongmin
authors.initials: Y
authors.lastname: He
authors.affiliation: Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, USA.
authors.forename: Antony
authors.initials: A
authors.lastname: George
authors.affiliation: Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, USA.
authors.forename: Liehui
authors.initials: L
authors.lastname: Ge
authors.affiliation: Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, USA.
authors.forename: Yongji
authors.initials: Y
authors.lastname: Gong
authors.affiliation: Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, USA.
authors.forename: Pei
authors.initials: P
authors.lastname: Dong
authors.affiliation: Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, USA.
authors.forename: Zehua
authors.initials: Z
authors.lastname: Jin
authors.affiliation: Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, USA.|Applied Physics Department, State University of Campinas, Campinas-SP, 13083-959, Brazil.
authors.forename: Gustavo
authors.initials: G
authors.lastname: Brunetto
authors.affiliation: Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, USA.
authors.forename: Weibing
authors.initials: W
authors.lastname: Chen
authors.affiliation: Department of Biomedical Engineering, University of Houston, Houston, Texas 77004, USA.
authors.forename: Zuan-Tao
authors.initials: ZT
authors.lastname: Lin
authors.affiliation: Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Baines
authors.affiliation: Applied Physics Department, State University of Campinas, Campinas-SP, 13083-959, Brazil.
authors.forename: Douglas S
authors.initials: DS
authors.lastname: Galvão
authors.affiliation: Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, USA.
authors.forename: Jun
authors.initials: J
authors.lastname: Lou
authors.affiliation: Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, USA.
authors.forename: Enrique
authors.initials: E
authors.lastname: Barrera
authors.affiliation: Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106, USA.
authors.forename: Kaustav
authors.initials: K
authors.lastname: Banerjee
authors.affiliation: Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Vajtai
authors.affiliation: Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005, USA.
authors.forename: Pulickel
authors.initials: P
authors.lastname: Ajayan
references.citation: ACS Nano. 2015 Feb 24;9(2):1099-107
references.pmid: 25629805
references.citation: Nano Lett. 2015 Mar 11;15(3):1883-90
references.pmid: 25715122
references.citation: Nat Mater. 2014 Dec;13(12):1135-42
references.pmid: 25262094
references.citation: ACS Nano. 2014 Aug 26;8(8):8285-91
references.pmid: 25062121
references.citation: Nano Lett. 2015 May 13;15(5):2852-62
references.pmid: 25723363
references.citation: J Phys Condens Matter. 2009 Sep 30;21(39):395502
references.pmid: 21832390
references.citation: ACS Nano. 2014 Feb 25;8(2):1263-72
references.pmid: 24392873
references.citation: Nat Nanotechnol. 2014 Sep;9(9):676-81
references.pmid: 25108809
references.citation: Nat Nanotechnol. 2014 Apr;9(4):262-7
references.pmid: 24608231
references.citation: J Am Chem Soc. 2009 Apr 8;131(13):4808-18
references.pmid: 19334776
references.citation: ACS Nano. 2014 Aug 26;8(8):8292-9
references.pmid: 25019534
references.citation: Nat Nanotechnol. 2014 Sep;9(9):664-5
references.pmid: 25182037
references.citation: Science. 2012 Feb 10;335(6069):698-702
references.pmid: 22323816
references.citation: Nat Mater. 2015 Dec;14(12):1195-205
references.pmid: 26585088
references.citation: Chem Soc Rev. 2010 May;39(5):1805-34
references.pmid: 20419220
references.citation: Nat Commun. 2014 Oct 20;5:5290
references.pmid: 25327957
references.citation: Nat Nanotechnol. 2014 Apr;9(4):268-72
references.pmid: 24608230
references.citation: Adv Mater. 2012 Jul 10;24(26):3549-54
references.pmid: 22678832
references.citation: Nat Nanotechnol. 2014 Apr;9(4):257-61
references.pmid: 24608229
references.citation: Nat Chem. 2015 Jan;7(1):45-9
references.pmid: 25515889
references.citation: Langmuir. 2010 Jun 15;26(12):9575-83
references.pmid: 20429522
references.citation: Nat Chem. 2013 Apr;5(4):263-75
references.pmid: 23511414
references.citation: J Am Chem Soc. 2013 Mar 27;135(12):4584-7
references.pmid: 23472859