PUBLIC

Jan-Willem J. Clerix,a,b A. Sanz-Matias,a S. Armini,b J. N. Harvey,a A. Delabiea,b

a Dep. of chem., KU Leuven, Leuvenb imec, Leuven

Structural phases of alkanethiolate self-assembled

monolayers (C1-12) on Cu by density functional theory

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ASD through SAMs, from model to method

⊖S(CH2)5CH3

Cu SiO2

ASD through SAMs, from model to method

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Structure at the interface

SAM structure: density, phase

Reactivity SAM-surface

ASD through SAMs, from model to method

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Structure at the interface

Reactivity SAM-surface

SAM structure: density, phase

Generic model of SAM formation

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Lying-down phases

Standing-up phases

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Schwartz, D. K. An. Rev. Phys. Chem. 2001, 52.

Density functional theory, chain length and coverage

Periodic, dispersion corrected density functional theory*

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Density functional theory, chain length and coverage

Periodic, dispersion corrected density functional theory*

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Density functional theory, chain length and coverage

Periodic, dispersion corrected density functional theory*

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thiolates∙cm-22.08∙10141.04∙1014 4.16∙1014 5.49∙1014 8.32∙1014

(4x4)

c(4x4)

(2x2) c(2x2)

c(2x6)Cu[100]: 16.64 1014 atcm-2

Yang, Y. C. Langmuir 2012, 28.

Driver, S. M. Surf. Sci. 2001, 488.

Vollmer, S. Langmuir 2001, 17.

Relative stability as a guide to phase behavior

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Cu[100] + y HSR → Cu[100][−SR]x+ y−x HSR+ ൗx 2 H2*

Short thiolates show linear adsorption

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0.3 nm

thiolates∙cm-22.08∙10141.04∙1014 4.16∙1014 5.49∙1014 8.32∙1014

Short thiolates show linear adsorption

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Short thiolates show linear adsorption

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-168 kJ/mol

-17 kJ/mol

-141 kJ/mol

-176 kJ/mol

-168 kJ/mol

Hexanethiolate shows the onset of phase behavior

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0.8 nm

thiolates∙cm-22.08∙10141.04∙1014 4.16∙1014 5.49∙1014 8.32∙1014

Hexanethiolate shows the onset of phase behavior

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0.8 nm

thiolates∙cm-22.08∙10141.04∙1014 4.16∙1014 5.49∙1014 8.32∙1014

Hexanethiolate shows the onset of phase behavior

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Hexanethiolate shows the onset of phase behavior

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+36 kJ/mol

-198 kJ/mol

-165 kJ/mol

-199 kJ/mol

Dodecanethiolate displays rich phase behavior

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Dodecanethiolate displays rich phase behavior

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-310 kJ/mol

-127 kJ/mol

-206 kJ/mol

-289 kJ/mol

Dodecanethiolate displays rich phase behavior

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Chain length determines structural phase

The short thiolates

Linear adsorption behavior, saturate at 8.32∙1014 th/cm2

The intermediate thiolate

Transition from lying-down to standing-up between 2.08 and

4.16∙1014 th/cm2, saturate at 5.49∙1014 th/cm2

The long thiolate

Transition from lying-down to standing-up between 1.04 and

2.08∙1014 th/cm2, saturate at 5.49∙1014 th/cm2

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Chain length determines structural phase

The short thiolates

Linear adsorption behavior, saturate at 8.32∙1014 th/cm2

The intermediate thiolate

Transition from lying-down to standing-up between 2.08 and

4.16∙1014 th/cm2, saturate at 5.49∙1014 th/cm2

The long thiolate

Transition from lying-down to standing-up between 1.04 and

2.08∙1014 th/cm2, saturate at 5.49∙1014 th/cm2

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Chain length determines structural phase

The short thiolates

Linear adsorption behavior, saturate at 8.32∙1014 th/cm2

The intermediate thiolate

Transition from lying-down to standing-up between 2.08 and

4.16∙1014 th/cm2, saturate at 5.49∙1014 th/cm2

The long thiolate

Transition from lying-down to standing-up between 1.04 and

2.08∙1014 th/cm2, saturate at 5.49∙1014 th/cm2

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Saturation content and phase transitions depend on chain length

regime

Optimal passivation for ASD is a compromise between chain length

and surface content

Long thiolates are computationally too demanding, short thiolates

are not accurate enough

Intermediate thiolates approximate long thiolate behavior sufficiently

sufficiently

Conclusions

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Saturation content and phase transitions depend on chain length

regime

Optimal passivation for ASD is a compromise between chain length

and surface content

Long thiolates are computationally too demanding, short thiolates

are not accurate enough

Intermediate thiolates approximate long thiolate behavior sufficiently

sufficiently

Conclusions

ASD through SAMs, from model to method

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Structure at the interface

SAM structure: density, phase

Reactivity SAM-surface

✓

ASD through SAMs, from model to method

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Reactivity SAM-surface