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Carbon dangling bonds in photodegraded polymer:fullerene solar cells (Conference Presentation)
Author(s): Fadzai Fungura; William Robin Lindemann; Joseph Shinar; Ruth Shinar

Paper Abstract

Intrinsic photodegradation of organic solar cells, theoretically attributed to C-H bond rearrangement/breaking, remains a key commercialization barrier. This work presents, via dark electron paramagnetic resonance (EPR), the first experimental evidence for metastable C dangling bonds (DBs) formed by blue/UV irradiation of polymer:fullerene blend films in nitrogen. The DB density increased with irradiation and decreased ~4 fold after 2 weeks in the dark. The dark EPR also shows increased densities of other spin-active sites in photodegraded polymer, fullerene, and polymer:fullerene blend films, consistent with broad electronic measurements of fundamental properties, including defect/gap state densities. The EPR and electronic measurements enable identification of defect states, whether in the polymer, fullerene, or at the donor/acceptor (D/A) interface. Importantly, the EPR results indicate that the DBs are at the D/A interface, as they were present only in the blend films. The role of polarons in interface DB formation will also be discussed.

Paper Details

Date Published: 19 September 2017
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Proc. SPIE 10363, Organic, Hybrid, and Perovskite Photovoltaics XVIII, 103631B (19 September 2017); doi: 10.1117/12.2275054
Show Author Affiliations
Fadzai Fungura, Iowa State Univ. of Science and Technology (United States)
William Robin Lindemann, Iowa State Univ. of Science and Technology (United States)
Joseph Shinar, Iowa State Univ. of Science and Technology (United States)
Ruth Shinar, Iowa State Univ. of Science and Technology (United States)


Published in SPIE Proceedings Vol. 10363:
Organic, Hybrid, and Perovskite Photovoltaics XVIII
Zakya H. Kafafi; Paul A. Lane; Kwanghee Lee, Editor(s)

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