SKM 2023 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 1: Focus: Organic Solar Cells Based on Non-fullerene Acceptors: Loss Mechanism and Options for Above 20 % Efficiencies I
CPP 1.4: Talk
Monday, March 27, 2023, 10:30–10:45, GÖR 226
Reconnoitering the impact of fluorination on both donor and non-fullerene acceptor in bulk heterojunction organic photovoltaics — •Shahidul Alam1, Jafar I. Khan1, Vojtech Nádaždy3, Tomáš Váry3, Aurelien D. Sokeng2, Md Moidul Islam2, Christian Friebe2, Wejdan Althobaiti2, Martin Hager2, Ulrich S. Schubert2, Carsten Deibel4, Denis Andrienko5, Frédéric Laquai1, and Harald Hoppe2 — 1KAUST Solar Center (KSC), Kingdom of Saudi Arabia — 2FSU Jena, Germany — 3Slovak Academy of Sciences, Bratislava — 4TU Chemnitz, Germany — 5MPIP, Mainz, Germany
Organic solar cells' performance can be often effectively improved through fluorination of the donor and/or non-fullerene acceptor (NFA). The end-group fluorination of the well-known NFA ITIC yields further extension of the absorption spectrum to the near infrared, which results in an increment of the device's photocurrent as compared to the non-fluorinated version. Herein, ITIC and two fluorinated variants of ITIC (ITIC-2F* and ITIC-4F) were synthesized and systematically investigated the influence of end-group fluorination physicochemical properties, optical properties, and photovoltaic performance. Photovoltaic parameters are discussed in terms of exciton quenching, charge generation, charge dissociation, and recombination losses. Specifically, it is found that fluorinated acceptors control the devices' open circuit voltage. All the results shed light on the importance of the energy landscape and the quadrupole moment of acceptor beyond the underlying donor-acceptor interface.