Berlin 2024 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 36: Organic Electronics and Photovoltaics III

CPP 36.5: Talk

Thursday, March 21, 2024, 10:30–10:45, H 0110

Photophysics of Poly(3-hexylthiophene): Non-Fullerene Acceptor Based Organic Solar Cells — •Wejdan Althobaiti, Julien Gorenflot, Catherine De Castro, Jafar Khan, Shahidul Alam, Christopher Petoukhoff, George Harrison, Stefaan De Wolf, and Frédéric Laquai — King Abdullah University of Science and Technology (KAUST), KAUST Solar Center (KSC), Physical Sciences and Engineering Division, Saudi Arabia

The efficiency of P3HT:Non-fullerene acceptor (NFA) based solar cells lacks considerably behind many other polymer donor:NFA systems. For reasons which are yet incomprehensible. Here, we report on a series of P3HT:NFA solar cells, and elucidate the origin of performance losses in terms of the photophysical processes. It is a matter of fact that the interfacial ionization energy (IE) offset is a critical parameter in NFA-based blends in determining the efficiency of the exciton-to-charge transfer (CT) state conversion. We show that while large IE offsets in excess of >0.9 eV still facilitate complete exciton quenching, the device internal quantum efficiency (IQE) is limited by geminate and / or non-geminate recombination processes in P3HT-based photoactive blends. Our finding shows a drop in IQE when the diagonal bandgap of the photoactive blend i.e the difference between the IE of the donor and the electron affinity (EA) of the acceptor is small irrespective of the IE offset. Understanding the relation between the IE offsets, EA offsets at the interface of donor and acceptor materials, and the performance of organic solar cells could improve the charge generation efficiency.

Keywords: P3HT; Internal Quantum Efficiency, IQE; Ionization Energy Offset, IE Offset; Diagonal Bandgap; Non-fullerene, NFA