April 22 - 26, 2024
Seattle, Washington
May 7 - 9, 2024 (Virtual)
Symposium Supporters
2024 MRS Spring Meeting
EN04.07.01

Charge Generation in Neat Non-Fullerene Acceptor Domains

When and Where

Apr 25, 2024
8:30am - 9:00am
Room 328, Level 3, Summit

Presenter(s)

Co-Author(s)

Natalie Banerji1,Kaila Yallum1

University of Bern1

Abstract

Natalie Banerji1,Kaila Yallum1

University of Bern1
Non-fullerene acceptors (NFAs) are exciting molecules allowing high efficiency in organic photovoltaic (OPV) blends with conjugated polymers. Interestingly, charges can also be generated by neat NFA films without additional donor. To understand the origins of exciton dissociation in neat NFAs, we have looked at the impact of aggregation, external electric field end non-linear effects. We used solvatochromism in order to gain insight on charge redistribution after excitation in isolated NFAs. We found that unaggregated NFAs feature a more dipolar excited state, revealing intramolecular charge transfer (ICT) character. This ICT character, however, is not enough to generate separated charges. Aggregation is the key to exciton dissociation in neat NFAs, which we observe with TA of solutions and films of several different NFAs. To explore the impact of an electric field on exciton dissociation in neat NFA devices, we used bias-dependent external quantum efficiency (EQE) and transient absorption (TA) spectroscopy. Electromodulated differential absorption (EDA) measurements then allowed us to observe charge transport under bias. Excitation correlation spectroscopy and fluence-dependent TA finally revealed how non-linear effects can increase the charge yield. Lastly, we comment on whether the neat domain charge generation significantly affects the photophysics of blends or not.

Symposium Organizers

Derya Baran, King Abdullah University of Science and Technology
Dieter Neher, University of Potsdam
Thuc-Quyen Nguyen, University of California, Santa Barbara
Oskar Sandberg, Åbo Akademi University

Symposium Support

Silver
Enli Technology Co., Ltd.

Bronze
1-Material, Inc.

Session Chairs

Tayebeh Ameri
Thomas Anthopoulos

In this Session