title: Abnormal strong burn-in degradation of highly efficient polymer solar cells caused by spinodal donor-acceptor demixing.
abstract: The performance of organic solar cells is determined by the delicate, meticulously optimized bulk-heterojunction microstructure, which consists of finely mixed and relatively separated donor/acceptor regions. Here we demonstrate an abnormal strong burn-in degradation in highly efficient polymer solar cells caused by spinodal demixing of the donor and acceptor phases, which dramatically reduces charge generation and can be attributed to the inherently low miscibility of both materials. Even though the microstructure can be kinetically tuned for achieving high-performance, the inherently low miscibility of donor and acceptor leads to spontaneous phase separation in the solid state, even at room temperature and in the dark. A theoretical calculation of the molecular parameters and construction of the spinodal phase diagrams highlight molecular incompatibilities between the donor and acceptor as a dominant mechanism for burn-in degradation, which is to date the major short-time loss reducing the performance and stability of organic solar cells.
authors.affiliation: Institute of Materials for Electronics and Energy Technology (i-MEET), Department of Materials Science and Engineering, Friedrich-Alexander University Erlangen-Nürnberg, Martensstrasse 7, 91058 Erlangen, Germany.
authors.forename: Ning
authors.initials: N
authors.lastname: Li
authors.affiliation: Institute of Materials for Electronics and Energy Technology (i-MEET), Department of Materials Science and Engineering, Friedrich-Alexander University Erlangen-Nürnberg, Martensstrasse 7, 91058 Erlangen, Germany.
authors.forename: José Darío
authors.initials: JD
authors.lastname: Perea
authors.affiliation: Crystallography and Structural Physics, Department of Physics, Friedrich-Alexander University Erlangen-Nürnberg, Staudtstrasse 3, 91058 Erlangen, Germany.
authors.forename: Thaer
authors.initials: T
authors.lastname: Kassar
authors.affiliation: Institute of Materials for Electronics and Energy Technology (i-MEET), Department of Materials Science and Engineering, Friedrich-Alexander University Erlangen-Nürnberg, Martensstrasse 7, 91058 Erlangen, Germany.
authors.forename: Moses
authors.initials: M
authors.lastname: Richter
authors.affiliation: Institute of Materials for Electronics and Energy Technology (i-MEET), Department of Materials Science and Engineering, Friedrich-Alexander University Erlangen-Nürnberg, Martensstrasse 7, 91058 Erlangen, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Heumueller
authors.affiliation: Institute of Materials for Electronics and Energy Technology (i-MEET), Department of Materials Science and Engineering, Friedrich-Alexander University Erlangen-Nürnberg, Martensstrasse 7, 91058 Erlangen, Germany.
authors.forename: Gebhard J
authors.initials: GJ
authors.lastname: Matt
authors.affiliation: Institute of Materials for Electronics and Energy Technology (i-MEET), Department of Materials Science and Engineering, Friedrich-Alexander University Erlangen-Nürnberg, Martensstrasse 7, 91058 Erlangen, Germany.|Erlangen Graduate School in Advanced Optical Technologies (SAOT), Paul-Gordan-Strasse 6, 91052 Erlangen, Germany.
authors.forename: Yi
authors.initials: Y
authors.lastname: Hou
authors.affiliation: Institute of Materials for Electronics and Energy Technology (i-MEET), Department of Materials Science and Engineering, Friedrich-Alexander University Erlangen-Nürnberg, Martensstrasse 7, 91058 Erlangen, Germany.
authors.forename: Nusret S
authors.initials: NS
authors.lastname: Güldal
authors.affiliation: Institute of Materials for Electronics and Energy Technology (i-MEET), Department of Materials Science and Engineering, Friedrich-Alexander University Erlangen-Nürnberg, Martensstrasse 7, 91058 Erlangen, Germany.
authors.forename: Haiwei
authors.initials: H
authors.lastname: Chen
authors.affiliation: Institute of Materials for Electronics and Energy Technology (i-MEET), Department of Materials Science and Engineering, Friedrich-Alexander University Erlangen-Nürnberg, Martensstrasse 7, 91058 Erlangen, Germany.
authors.forename: Shi
authors.initials: S
authors.lastname: Chen
authors.affiliation: Institute of Materials for Electronics and Energy Technology (i-MEET), Department of Materials Science and Engineering, Friedrich-Alexander University Erlangen-Nürnberg, Martensstrasse 7, 91058 Erlangen, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Langner
authors.affiliation: Crystallography and Structural Physics, Department of Physics, Friedrich-Alexander University Erlangen-Nürnberg, Staudtstrasse 3, 91058 Erlangen, Germany.
authors.forename: Marvin
authors.initials: M
authors.lastname: Berlinghof
authors.affiliation: Crystallography and Structural Physics, Department of Physics, Friedrich-Alexander University Erlangen-Nürnberg, Staudtstrasse 3, 91058 Erlangen, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Unruh
authors.affiliation: Institute of Materials for Electronics and Energy Technology (i-MEET), Department of Materials Science and Engineering, Friedrich-Alexander University Erlangen-Nürnberg, Martensstrasse 7, 91058 Erlangen, Germany.|Erlangen Graduate School in Advanced Optical Technologies (SAOT), Paul-Gordan-Strasse 6, 91052 Erlangen, Germany.|Bavarian Center for Applied Energy Research (ZAE Bayern), Immerwahrstrasse 2, 91058 Erlangen, Germany.
authors.forename: Christoph J
authors.initials: CJ
authors.lastname: Brabec