Journal Article

PUBDB-2025-00176

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Nanometer-Thick ITIC Bulk Heterojunction Films as Non-Fullerene Acceptors in Organic Solar Cells

Huang, T.-Y. ; Le Brun, A. P. ; Sochor, B.Extern*DESY* ; Wu, C.-M.Extern* ; Bulut, Y.Extern*DESY* ; Müller-Buschbaum, P.Extern* ; Roth, S. V.XFEL.EU*DESY* ; Yang, Y. (Corresponding author)Extern*

2024
ACS Publications Washington, DC

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Please use a persistent id in citations: doi:10.1021/acsanm.4c02865

Abstract: The nanomorphology of bulk heterojunctions (BHJs) plays a critical role in determining the performance of non-fullerene organic solar cells (OSCs). Thermal annealing is commonly used to reorganize the donor and acceptor phases within the BHJs. In this study, we investigate the vertical morphology of BHJ blend films incorporating the poly[(5,6-difluoro-2,1,3-benzothiadiazol-4,7-diyl)-alt-(3,3‴-di(2-octyldodecyl)-2,2′;5′,2″;5″,2‴-quaterthiophen-5,5‴-diyl)] (PffBT4T-2OD) polymer as the donor and 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2′,3′-d′]-s-indaceno[1,2-b:5,6-b′]dithiophene (ITIC) as the acceptor. Neutron reflectivity patterns and scattering length density profiles reveal that the surface of the BHJ films became diffuse when the annealing temperature was above 150 °C. We further find that mitigated agglomeration of PffBT4T-2OD side chains exhibits minimal impact on morphology post-annealing. Instead, ITIC molecules trigger aggregations, accompanied by interface diffusion and increased film roughness. X-ray scattering confirms a 5-fold increase in aggregated ITIC nanodomains after annealing. Our findings highlight that unstable ITIC phases dominate the BHJ morphology of thin films, leading to the thermal instability of OSCs. This study enhances our understanding of the BHJ morphology and offers insights into improving the performance of energy conversion devices.

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Contributing Institute(s):

1. DOOR-User (DOOR ; HAS-User)
2. Spectroscopy of molecular processes (FS-SMP)
3. Experimentebetreuung PETRA III (FS-PET-D)

Research Program(s):

1. 632 - Materials – Quantum, Complex and Functional Materials (POF4-632) (POF4-632)
2. 6G3 - PETRA III (DESY) (POF4-6G3) (POF4-6G3)
3. DFG project G:(GEPRIS)390776260 - EXC 2089: e-conversion (390776260) (390776260)
4. SINE2020 - World class Science and Innovation with Neutrons in Europe 2020 – SINE2020 (654000) (654000)

Experiment(s):

1. PETRA Beamline P03 (PETRA III)

Appears in the scientific report 2024

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Database coverage:
; Clarivate Analytics Master Journal List ; Current Contents - Engineering, Computing and Technology ; Current Contents - Physical, Chemical and Earth Sciences ; Essential Science Indicators ; IF >= 5 ; JCR ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

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