Imperial College London
Alternate

ProfessorSandrineHeutz

Faculty of Engineering, Department of Materials

Head of the Department of Materials
 
 
 
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Contact

 

+44 (0)20 7594 6727s.heutz

 
 
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Location

 

201.BRoyal School of MinesSouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@inbook{Tseng:2020:10.1142/S1088424619501700,
author = {Tseng, HH and Serri, M and Harrison, N and Heutz, S},
booktitle = {Porphyrin Science By Women (In 3 Volumes)},
doi = {10.1142/S1088424619501700},
pages = {924--931},
title = {Properties and degradation of manganese(III) porphyrin thin films formed by high vacuum sublimation},
url = {http://dx.doi.org/10.1142/S1088424619501700},
year = {2020}
}
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RIS format (EndNote, RefMan)

TY  - CHAP
AB  - Manganese porphyrins are of interest due to the optical, electronic and magnetic properties of the central metal ion, coupled to the low bandgap of the polyaromatic ring. These attractive characteristics are harnessed in solutions or in ultra-thin films, such as, for example, self-assembled monolayers. However, for devices, thicker films deposited using a controlled and reproducible method are required. Here we present the morphological, structural, chemical and optical properties of manganese(III) tetraphenylporphyrin chloride (MnTPPCl) thin films deposited using organic molecular beam deposition, typically employed to process analogue molecules for applications such as organic photovoltaics. We find, using a combination of UV-vis and X-ray photoelectron spectroscopies, that the sublimation process leads to the scission of the Mn-Cl bond. The resultant film is a Mn(II)TPP:Mn(III)TPPCl blend where approximately half the molecules have been reduced. Following growth, exposure to air oxidizes the Mn(II)TPP molecule. Through quantitative analysis of the time-dependent optical properties, the oxygen diffusion coefficient (D) ~1.9 × 10-17 cm2/s is obtained, corresponding to a slow bulk oxidation following fast oxidation of a 8-nm-thick surface layer. The bulk diffusion D is lower than for analogous polycrystalline films, suggestion that grain boundaries, rather than molecular packing, are the rate-limiting steps in oxidation of molecular films. Our results highlight that the stability of the axial ligands should be considered when depositing metal porphyrins from the vapor phase, and offer a solvent-free route to obtain reproducible and smooth thin films of complex materials for engineering film functionalities.
AU  - Tseng,HH
AU  - Serri,M
AU  - Harrison,N
AU  - Heutz,S
DO  - 10.1142/S1088424619501700
EP  - 931
PY  - 2020///
SN  - 9789811223556
SP  - 924
TI  - Properties and degradation of manganese(III) porphyrin thin films formed by high vacuum sublimation
T1  - Porphyrin Science By Women (In 3 Volumes)
UR  - http://dx.doi.org/10.1142/S1088424619501700
ER  -
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