Polymorphism in Non-Fullerene Acceptors Based on Indacenodithienothiophene

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 conside...

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Detalhes bibliográficos
Autores: Marina Barbier, Sara Luisa, Scaccabarozzi, Alberto D., Gutiérrez Fernández, Edgar, Solano, Eduardo, Khirbat, Aditi, Ciammaruchi, Laura, Iturrospe Ibarra, Amaia, Balzer, Alex, Yu, Liyang, Gabirondo Amenabar, Elena, Monnier, Xavier, Sardon Muguruza, Haritz, Anthopoulos, Thomas D., Caironi, Mario, Campoy Quiles, Mariano, Müller, Christian, Cangialosi, Daniele, Stingelin, Natalie, Martín Pérez, Jaime
Tipo de documento: artigo
Data de publicação:2021
País:España
Recursos:Universidad del País Vasco
Repositório:Addi. Archivo Digital para la Docencia y la Investigación
OAI Identifier:oai:addi.ehu.eus:10810/55029
Acesso em linha:http://hdl.handle.net/10810/55029
Access Level:Acceso aberto
Palavra-chave:organic semiconductors
organic solar cells
polimorphism
polymer solar-cells
electron-acceptor
charge-transport
side-chains
efficiency
confinement
selection
organic electronics
non-fullerene acceptor
Descrição
Resumo: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.

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