CEA-Saclay IRAMIS/SPCSI and SPEC. ANR MEMO project. Coll. CEA-DAE

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1 ynthesis and grafting of n and p type σ-π-σ systems on substrates for molecular electronic applications. Fabrice Moggia, Bruno Jousselme, Gaël Robert, athalie Lidgi-Guigui Guigui, Vincent Derycke,, Jean-Philippe Bourgoin and erge Palacin CEA-aclay IRAMI/PCI and PEC AR MEM project Dinesh K. Aswal, J V. Yakhmi Bhabha Atomic Research Centre Coll. CEA-DAE Chimie des urfaces et Interfaces

2 tructure of the molecular diode : anotube / Molecules / licon metal nanotube 2 ++ (1) Connect few molecules (2) Avoid metal evaporation to contact the molecules m σ π WTs σ: alkyl-chains act as tunnel barriers (3) Prove a negative differential resistance effect at room temperature n σ π: conjugated part acts as the potential well licon Chimie des urfaces et Interfaces

3 negative differential resistance (DR) effect DR peak should appear whenever an energy level of the molecule comes into resonance with the electrons of the conduction band of the silicon or holes in the valence band of the silicon. ano Letters 4, 55 (24) Chimie des urfaces et Interfaces

4 equential synthesis of a σ-π-σ monolayer on silicon (L. Baraton Ph. D Thesis) Post-functionalization way ( ) m H Y Y ( ) m ( ) n ( ) n ( ) n Z HF Δou hν Y = Carboxylic Acid or activated ester H, Esterification reaction on a monolayer Données expérimentales (H 2 C) 6 H Transmittance (%) νch 3 νch 2 νc=ester νc= amide νc=c aromatique Intensité p 1 / 2 2p 3 / 2 x Ligne de base Wavelenght (cm -1 ) Energie de liaison (ev) Chimie des urfaces et Interfaces

5 Approach used in the project Direct Grafting ( ) m ( ) m ( ) n ( ) n Etching X Chosen compounds Terthiophene derivative aphthalene derivative R R R= CH=CH 2, CH 2 H R= CH=CH 2, CH 2 H Electron donor (p-type) Electron acceptor (n-type) Chimie des urfaces et Interfaces

6 ptics and redox properties of the conjugated systems I/ μa Working: Carbone.1 M Bu 4 BF 4 in CH 2 Cl 2, V = 1 mv s -1 pectres normalisés In CH 2 Cl 2, Absorption Emission E/V vs Ferrocene λ / nm ptic Gap : 432 nm 2.9 ev In CH 2 Cl 2, I/μA pectres normalisés Emission Absorption E/V vs Ferrocene λ / nm ptic gap : 384 nm 3.2 ev Chimie des urfaces et Interfaces

7 Energy level of the compounds targeted LUM -3-4 CB -3.7 LUM T3 CT -5 VB aphta HM -5.1 HM Chimie des urfaces et Interfaces

8 ynthesis of p-type compound : Terthiophene derivative (3T) ynthesis of alkene and thiol compounds C C BuLi, 8, Br(CH 2 ) 2 C DMF CsH.H 2, Br(CH 2 ) 5 CH 3 MeH, DMF CsH.H 2, Br(CH2) 4 CH=CH 2 MEH, DMF C ( ) 3 ( ) 3 Br Br Ac - K + THF Br 4 CsH.H 2, MeH, DMF 4 CsH.H 2, MeH, DMF DMF ( ) 3 6 H Chimie des urfaces et Interfaces

9 ynthesis of n-type compound : aphthalene tetracarboxiimide (aph) ynthesis of alkene and thiol compounds H 2 (CH 2 ) 5 CH 3, H 2 -n-prh Acétate d ammonium CHCl 3, ACH 6-Aminohexènol, PPh 3 DIAD THF H Br Br H Br Phtalimide de potassium Acétone Ac - K + THF H 2 H 2 EtH DMF, 13 Reflux H H 2 Chimie des urfaces et Interfaces

10 Geometries optimisation of 3T and aph thiols derivatives 3TH aphh 85 C A A 9 C Gaussian 98 DFT (Becke3lyp), Bases : 6-31G*. Chimie des urfaces et Interfaces

11 AMs on gold Conditions Thiol Concentration : 1-3 M olvent : Methylene Chloride/Ethanol θ 1-11 Reaction time : 24 hours Contact angle measurements 11 1 Contact angles dodecaneh 3TH APH 4 3 3T-H Mesures Chimie des urfaces et Interfaces

12 XP analysis of AMs on gold 17 Counts / s Counts / s p Binding Energy / ev Au4p 3/2 Au4f 5/2 Au4d Au4d 3/2 5/2 C1s 2p 2s 18 Au4f 7/ Counts / s Counts / s p Binding Energy / ev Au4p 3/2 1s Au4d 3/2 Au4d 5/2 1s C1s Au4f 5/2 2p Au4f 7/ Binding Energy / ev Chimie des urfaces et Interfaces Binding Energy / ev

13 FT-IR analysis of AMs on gold H H 3TH aphh 1,2 in CCl 4 1 1,5 In CCl ,25 9 Transmittance/% 1,1 1, 3TH AM 8 7 Transmittance/% Transmittance/% 1, 99,75 99,5 aphh AM Transmittance/% 99, , ,8 5 99, Wavenumber/cm -1 Wavenumber/cm -1 Chimie des urfaces et Interfaces

14 Cyclic voltamperometry of a AM of 3TH on gold I / µa Working: Gold.1 M Bu 4 PF 6 in CH 2 Cl 2, V = 1 mv s -1 I / µa Working: Gold.1 M Bu 4 PF 6 in CH 2 Cl 2, V = 1 mv s E / V vs Ferrocene -75 E red = V E / V vs Ferrocene E 1 = 325 mv Versus ferrocene -11 mv / in solution π - π interactions -2 mv / in solution Dimerization, Thiolale, Alkyl Chain Chimie des urfaces et Interfaces

15 Morphology of the AMs - TM DodecaneH 3TH aphthh Chimie des urfaces et Interfaces Lionel Patrone University of Toulon

16 I/V measurements - TM DodecaneH 3TH aphthh Chimie des urfaces et Interfaces Lionel Patrone University of Toulon

17 Contact with InGa Eutectic and I/V measurements Whitesides & al., Angew.Chem.Int.Ed. 47, 142 [28] DodecaneH 3TH aphthh 2, 5 3, 1,5 2,5 1, 2, I (µa),5, I (na) -5 I (na) 1,5 1, -,5-1, -1,5-1,5, -2, -,4 -,2,,2,4 V Au (V) -,4 -,2,,2,4 V Au (V) -,5 -,4 -,2,,2,4 V Au (V) Chimie des urfaces et Interfaces Gaël Robert CEA aclay/pec

18 Hydrosilation reaction mechanism on IH H H H R, UV ou R H H H H R H 2 C CH H H R R H 2 C CH H H H 2 C CH 2 H etc... Chimie des urfaces et Interfaces

19 Grafting of the alkenes compounds on silicon Different ways were tested for the 3T derivative: ublimation sublimation impossible Dilution re-oxidation of the silicon Irradiation degradation Grafting eat Different ways were tested for the aphth derivative: ublimation sublimation impossible eat mp>2 Dilution re-oxidation of the silicon Grafting eat Chimie des urfaces et Interfaces

20 Grafting of the 3T on silicon p++ (1) Conditions : eat, 15 C, under vacuum, 12H Contact angle of 15 XP : 5 4 Global C 2 2p natif -H Count / s 3 2 Count / s T -3T 48h air Binding Energy (ev) Binding Energy (ev) Chimie des urfaces et Interfaces

21 Grafting of the aph on silicon n++ (111) Conditions : eat, 22 C, 2H, under vacuum (1-7 mbar) Contact angle of 1 XP analysis: 3 25 urvey 1s C1s 2s 2p p aphth H x Counts / s s Counts / s Binding Energy / ev Energy Binding / ev Chimie des urfaces et Interfaces

22 Cyclic Voltamperometry 3TAL aphal n (1)-P ++ CH 2 Cl 2, TEAP (.1M), 1 mv.s -1 3T on (1)-P Working: licon 111 n++.1 M Bu 4 PF 6 in CH 2 Cl 2, V = 1 mv s I (µa) 4 2 I / µa ,,2,4,6,8 1, E (mv) E / V vs vs Ag/Ag E / V vs Ferrocene Chimie des urfaces et Interfaces

23 Conclusion of the first part - ynthesis of two new σ-π-σ compounds with Thiol or alkene functions - Monolayers on gold and on silicon (Contact angle, XP, infrared spectroscopy, TM). - apthh has a better packing than 3TH on gold. - I/V measurements on gold (TM and Eutectic InGa) next on silicon Chimie des urfaces et Interfaces

24 Grafting on silicon via diazonium salts Coll. CEA-DAE ynthesis of -(2-(4-diazoniophenyl)ethyl)- -hexylnaphthalene-1,8:4,5-tetracarboxydiimide tetrafluoroborate Hexylamine DMF / Reflux DMF / 8 C 38 % 97 % 4-(2-aminoethyl) aniline BF 4 AC / -4 C 85 % H BF Α 2 + BF 4 - Chimie des urfaces et Interfaces

25 Grafting on potentio-dynamic condition on silicon Coll. CEA-DAE 2 + BF 4 - -e - 2x1-4 1x1-4 Working: licon 111 n++.1 M Bu 4 PF 6 in CH 2 Cl 2, V = 1 mv s -1 Current (A) 5x1-5 -5x1-5 -1x x Potential (V) vs Ag/Ag + CV recorded using diazonium salt of σ π σ molecules using H-terminated (111) as working electrode. ote the shift in the irreversible peak to higher potentials with increasing number of scans. Chimie des urfaces et Interfaces Coll. CEA-DAE

26 Analysis and characterizations of the thin films Coll. CEA-DAE - Contact Angle : 7 - Infrared spectrum Transmittance/% Transmittance/% Wavenumber/cm -1 7 Chimie des urfaces et Interfaces Coll. CEA-DAE

27 Analysis and characterizations of the thin films Coll. CEA-DAE 5 urvey C1s 35 C 1s 3 4 1s 25 Counts / s 3 2 1s Counts / s 2 15 C= 1 2s 2p Binding energy / ev Binding energy / ev 8 2p 7 6 Counts / s x Binding Energy / ev Chimie des urfaces et Interfaces Coll. CEA-DAE

28 Analysis and characterizations of the thin films Coll. CEA-DAE Working: licon 111 n++.1 M Bu 4 PF 6 in CH 2 Cl 2, V = 1 mv s -1 CV recorded for the electrografted organic layers on grafted using the reduction of diazonium salt. Chimie des urfaces et Interfaces

29 Current-voltage characteristic of the σ π σ layers (12 nm) grafted on using diazonium salt Chimie des urfaces et Interfaces Coll. CEA-DAE

30 Chimie des urfaces et Interfaces

31 Au TM tip Au TM tip Au TM tip V < V > Chimie des urfaces et Interfaces