Orientation-induced molecular rectification and nonlinear optical properties of a squaraine derivative

被引:22
作者
Ashwell, GJ [1 ]
Ewington, J [1 ]
Moczko, K [1 ]
机构
[1] Cranfield Univ, Nanomat Grp, Cranfield MK43 0AL, Beds, England
基金
英国工程与自然科学研究理事会;
关键词
D O I
10.1039/b413480j
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
Self- assembled monolayers (SAMs) obtained via the chemisorption of 2,4-bis-[N-methyl-N-(3-acetylsulfanylpropyl)-aminophenyl]-squaraine on gold are disordered with the molecules adopting vertical alignments via a single C3H6-S-Au anchoring group and horizontal alignments via two C3H6-S-Au groups located at opposite ends of the donor-acceptor-donor chromophore. The films exhibit asymmetric current-voltage characteristics with a rectification ratio of ca. 6 at +/- 1 V, this unexpected behaviour being induced by different molecular orientations at the interfaces with the electrodes: the donor groups are adjacent both top and bottom whereas the long axis of the D-A-D moiety is only in contact with the gold-coated substrate. The higher forward bias current invariably relates to electron flow from the substrate electrode adjacent to the horizontally aligned chromophores to the contact adjacent to the terminal donors of the vertically aligned molecules. In contrast, Langmuir-Blodgett (LB) films of the squaraine exhibit symmetrical I-V curves and aggregation-induced second-harmonic generation (SHG) with an effective second-order susceptibility of ca. 80 pm V-1 at 1.064 mum.
引用
收藏
页码:1154 / 1159
页数:6
相关论文
共 30 条
[1]   2,4-bis[4-(N,N-dibutylamino)phenyl]squaraine: X-ray crystal structure of a centrosymmetric dye and the second-order non-linear optical properties of its non-centrosymmetric Langmuir-Blodgett films [J].
Ashwell, GJ ;
Bahra, GS ;
Brown, CR ;
Hamilton, DG ;
Kennard, CHL ;
Lynch, DE .
JOURNAL OF MATERIALS CHEMISTRY, 1996, 6 (01) :23-26
[2]   2,4-bis [4-(N-methyl-N-alkylamino)phenyl]squaraines: Structure-property relationship and dependence of the type of aggregate upon the hydrophobicity of the alkyl group [J].
Ashwell, GJ ;
Roberts, MPS ;
Rees, ND ;
Bahra, GS ;
Brown, CR .
LANGMUIR, 1998, 14 (18) :5279-5284
[3]   Hybrid SAM/LB device structures: manipulation of the molecular orientation for nanoscale electronic applications [J].
Ashwell, GJ ;
Berry, M .
JOURNAL OF MATERIALS CHEMISTRY, 2005, 15 (01) :108-110
[4]   Rectifying Au-S-CnH2n-P3CNQ derivatives [J].
Ashwell, GJ ;
Chwialkowska, A ;
High, LRH .
JOURNAL OF MATERIALS CHEMISTRY, 2004, 14 (19) :2848-2851
[5]   Au-S-CnH2n-Q3CNQ:: self-assembled monolayers for molecular rectification [J].
Ashwell, GJ ;
Chwialkowska, A ;
High, LRH .
JOURNAL OF MATERIALS CHEMISTRY, 2004, 14 (15) :2389-2394
[6]   Molecular rectification:: Self-assembled monolayers in which donor-(π-bridge)-acceptor moieties are centrally located and symmetrically coupled to both gold electrodes [J].
Ashwell, GJ ;
Tyrrell, WD ;
Whittam, AJ .
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 2004, 126 (22) :7102-7110
[7]   PHOTOCONDUCTION IN MAGNESIUM PHTHALOCYANINE THIN-FILMS [J].
ASHWELL, GJ ;
BONHAM, JS ;
LYONS, LE .
AUSTRALIAN JOURNAL OF CHEMISTRY, 1980, 33 (07) :1619-1623
[8]   Do alkyl tunnelling barriers contribute to molecular rectification? [J].
Ashwell, GJ ;
Stokes, RJ .
JOURNAL OF MATERIALS CHEMISTRY, 2004, 14 (08) :1228-1230
[9]   Molecular rectification:: self-assembled monolayers of a donor-(π-bridge)-acceptor chromophore connected via a truncated Au-S-(CH2)3 bridge [J].
Ashwell, GJ ;
Tyrrell, WD ;
Whittam, AJ .
JOURNAL OF MATERIALS CHEMISTRY, 2003, 13 (12) :2855-2857
[10]   Molecular rectification:: asymmetric current-voltage curves from self-assembled monolayers of a donor-(π-bridge)-acceptor dye [J].
Ashwell, GJ ;
Hamilton, R ;
High, LRH .
JOURNAL OF MATERIALS CHEMISTRY, 2003, 13 (07) :1501-1503