Impact of gamma-ray irradiation on the electronic structures of PCBM and P3HT organic semiconductor films. (April 2021)

• Record Type: Journal Article
• Authors: Park, Sohyun; Choi, Seungsun; Lee, Hyunchan; Lee, Jiyeon; Woo, Yunseo; Jung, Yu-Jin; Jung, Young Mee; Jeong, Junkyeong; Park, Jeehong; Yi, Yeonjin; Park, Soohyung; Lee, Hyunbok
• Is Part Of: Polymer degradation and stability. Volume 186(2021)
• Publication Date: 2021-04
• Subjects: Gamma-ray -- XPS -- UPS -- PCBM -- P3HT; Polymers -- Deterioration -- Periodicals; Stabilizing agents -- Periodicals; Polymères -- Dégradation -- Périodiques; Stabilisants -- Périodiques; 668.9
• DOI: 10.1016/j.polymdegradstab.2021.109518
• Languages: English
• ISSNs: 0141-3910

Abstract

Highlights: The electronic structures of PCBM and P3HT after gamma-ray irradiation were studied. Significant oxidation was observed in the XPS and UPS spectra. Oxidation is attributed to the chemical interaction with atmospheric oxygen. The degree of oxidation is higher in PCBM than in P3HT. Organic semiconductors can be used as total-dose detectors for low doses. Abstract: Gamma-ray irradiation alters the material properties of organic semiconductors, especially the electronic structure. These changes due to ionization can be useful in dosimetry. Although there are some device-based reports, the effect of gamma-ray irradiation on the electronic structure of organic semiconductors is still unclear. In this study, we investigated the electronic structures of representative organic semiconductor films, namely, n-type [6, 6]-phenyl-C61 -butyric acid methyl ester (PCBM) and p-type poly(3-hexylthiophene-2, 5-diyl) (P3HT), after gamma-ray irradiation generated by a Cs-137 source. The X-ray and ultraviolet photoelectron spectra of the PCBM and P3HT films were measured for various gamma-ray doses. In both PCBM and P3HT, chemical interaction with atmospheric oxygen, assisted by high-energy photons, led to significant oxidation. However, the degree of oxidation of PCBM was considerably higher than that of P3HT. The oxidation also affects the valence electronic structures. The possible chemical structures of the oxidized PCBM and P3HT are estimated using density functional theory calculations.