Issue 42, 2022

Photooxidation of PC60BM: new insights from spectroscopy


This joint experimental–theoretical spectroscopy study of the fullerene derivative PC60BM ([6,6]-phenyl-C60-butyric acid methyl ester) aims to improve the understanding of the effect of photooxidation on its electronic structure. We have studied spin-coated thin films of PC60BM by X-ray Photoelectron Spectroscopy (XPS), Near-edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy, and Fourier Transform Infrared Spectroscopy (FTIR), before and after intentional exposure to simulated sunlight in air for different lengths of time. The π* resonance in the C1s NEXAFS spectrum was found to be a very sensitive probe for the early changes to the fullerene cage, while FTIR spectra, in combination with O1s NEXAFS spectra, enabled the identification of the oxidation products. The changes observed in the spectra obtained by these complementary methods were compared with the corresponding Density Functional Theory (DFT) calculated single-molecule spectra of a large set of in silico generated oxidation products of PC60BM where oxygen atoms were attached to the C60 cage. This comparison confirms that photooxidation of PC60BM disrupts the conjugation of the fullerene cage by a transition from sp2 to sp3-hybridized carbon and causes the formation of several oxidation products, earlier proposed for C60. The agreement between experimental and calculated IR spectra suggests moreover the presence of dicarbonyl and anhydride structures on the fullerene cage, in combination with cage opening at the adsorption site. By including PC60BM with physisorbed O2 molecules on the cage in our theoretical description in order to model oxygen diffused through the film, the experimental O1s XPS and O1s NEXAFS spectra could be reproduced.

Graphical abstract: Photooxidation of PC60BM: new insights from spectroscopy

Supplementary files

Article information

Article type
31 Jul 2022
13 Sep 2022
First published
14 Sep 2022
This article is Open Access
Creative Commons BY license

Phys. Chem. Chem. Phys., 2022,24, 25753-25766

Photooxidation of PC60BM: new insights from spectroscopy

I. E. Brumboiu, L. K.E. Ericsson, V. Blazinic, R. Hansson, A. Opitz, B. Brena and E. Moons, Phys. Chem. Chem. Phys., 2022, 24, 25753 DOI: 10.1039/D2CP03514F

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

Read more about how to correctly acknowledge RSC content.

Social activity