Polymorphism in Non-Fullerene Acceptors Based on Indacenodithienothiophene
Journal article, 2021

Organic solar cells incorporating non-fullerene acceptors (NFAs) have reached remarkable power conversion efficiencies of over 18%. Unlike fullerene derivatives, NFAs tend to crystallize from solutions, resulting in bulk heterojunctions that include a crystalline acceptor phase. This must be considered in any morphology-function models. Here, it is confirmed that high-performing solution-processed indacenodithienothiophene-based NFAs, i.e., ITIC and its derivatives ITIC-M, ITIC-2F, and ITIC-Th, exhibit at least two crystalline forms. In addition to highly ordered polymorphs that form at high temperatures, NFAs arrange into a low-temperature metastable phase that is readily promoted via solution processing and leads to the highest device efficiencies. Intriguingly, the low-temperature forms seem to feature a continuous network that favors charge transport despite of a poorly order along the pi-pi stacking direction. As the optical absorption of the structurally more disordered low-temperature phase can surpass that of the more ordered polymorphs while displaying comparable-or even higher-charge transport properties, it is argued that such a packing structure is an important feature for reaching highest device efficiencies, thus, providing guidelines for future materials design and crystal engineering activities.

non&#8208

organic solar cells

organic semiconductors

polimorphism

organic electronics

fullerene acceptors

Author

Sara Marina

University of the Basque Country (UPV/EHU)

Alberto D. Scaccabarozzi

King Abdullah University of Science and Technology (KAUST)

Istituto Italiano di Tecnologia

Edgar Gutierrez-Fernandez

University of the Basque Country (UPV/EHU)

Eduardo Solano

ALBA Synchrotron Light Facility

Aditi Khirbat

Georgia Institute of Technology

Laura Ciammaruchi

Institute of Material Science of Barcelona (ICMAB)

Amaia Iturrospe

Centro de Física de Materiales (CFM CSIC/EHU)

Alex Balzer

Georgia Institute of Technology

Liyang Yu

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry, Christian Müller Group

Elena Gabirondo

University of the Basque Country (UPV/EHU)

Xavier Monnier

Centro de Física de Materiales (CFM CSIC/EHU)

Donostia International Physics Center

Haritz Sardon

University of the Basque Country (UPV/EHU)

Thomas D. Anthopoulos

King Abdullah University of Science and Technology (KAUST)

Mario Caironi

Istituto Italiano di Tecnologia

Mariano Campoy-Quiles

Institute of Material Science of Barcelona (ICMAB)

Christian Müller

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry, Christian Müller Group

Daniele Cangialosi

Centro de Física de Materiales (CFM CSIC/EHU)

Natalie Stingelin

Georgia Institute of Technology

University of Bordeaux

Jaime Martin

University of A Coruña

University of the Basque Country (UPV/EHU)

Basque Foundation for Science (Ikerbasque)

Advanced Functional Materials

1616-301X (ISSN)

2103784

Subject Categories

Materials Chemistry

Other Physics Topics

Condensed Matter Physics

DOI

10.1002/adfm.202103784

More information

Latest update

6/2/2021 8