TY - JOUR
T1 - Charge Carrier Dynamics in Planar Heterojunction Organic Solar Cells
AU - Huang, Yexiao
AU - Chung, Sein
AU - Karuthedath, Safakath
AU - De Castro, Catherine S.P.
AU - Tang, Hua
AU - Jeong, Minyoung
AU - Lu, Shirong
AU - Cho, Kilwon
AU - Laquai, Frédéric
AU - Kan, Zhipeng
N1 - Funding Information:
Y.H. and S.C. contributed equally to this work. The authors acknowledge financial support from Guangxi Natural Science Foundation (2022GXNSFDA035066), National Natural Science Foundation of China (62275057), Guangxi University (A3120051029). The research reported in this publication was supported by funding from the King Abdullah University of Science and Technology (KAUST) Office of Sponsored Research (OSR) under Award No. OSR‐CRG2018‐3746, under Award No. ORA‐CRG8‐2019‐4025, and National Research Foundation of Korea (NRF) grant (NRF‐2020R1A2C3004477) funded by the Ministry of Science and ICT (MSIT) of the Korean government. Portions of this research were carried out at the 3C and 9A beam lines of the Pohang Accelerator Laboratory, Republic of Korea.
Publisher Copyright:
© 2023 Wiley-VCH GmbH.
PY - 2023/6
Y1 - 2023/6
N2 - The ionization energy (IE) offset of a donor–acceptor pair provides the driving force for hole transfer and subsequent free charge carrier generation in low-bandgap nonfullerene organic solar cells (OSCs). However, the interfacial energetic landscape in bulk heterojunction OSCs is determined by the materials’ electronic structure and intermolecular interactions at the donor/acceptor interface, causing local energy-level shifts and disorder. Herein, the impact of the IE offset on the charge transfer efficiency and charge carrier dynamics is systematically evaluated by characterizing PM6/ITIC, PM6/IT-2Cl, and PM6/IT-4Cl planar heterojunction (PHJ) solar cells. Ultrafast spectroscopy and time-resolved charge carrier density measurements reveal that an IE offset of about ≈0.5 eV leads to efficient hole transfer and subsequent free charge generation. Furthermore, bimolecular charge recombination and consequently triplet generation are significantly reduced in systems with high IE offset. This work underlines the importance of sizeable donor–acceptor IE offsets in PHJ nonfullerene OSCs as critical for high-efficiency donor/acceptor material and device design.
AB - The ionization energy (IE) offset of a donor–acceptor pair provides the driving force for hole transfer and subsequent free charge carrier generation in low-bandgap nonfullerene organic solar cells (OSCs). However, the interfacial energetic landscape in bulk heterojunction OSCs is determined by the materials’ electronic structure and intermolecular interactions at the donor/acceptor interface, causing local energy-level shifts and disorder. Herein, the impact of the IE offset on the charge transfer efficiency and charge carrier dynamics is systematically evaluated by characterizing PM6/ITIC, PM6/IT-2Cl, and PM6/IT-4Cl planar heterojunction (PHJ) solar cells. Ultrafast spectroscopy and time-resolved charge carrier density measurements reveal that an IE offset of about ≈0.5 eV leads to efficient hole transfer and subsequent free charge generation. Furthermore, bimolecular charge recombination and consequently triplet generation are significantly reduced in systems with high IE offset. This work underlines the importance of sizeable donor–acceptor IE offsets in PHJ nonfullerene OSCs as critical for high-efficiency donor/acceptor material and device design.
KW - bimolecular recombination
KW - energetic disorder
KW - hole transfer
KW - planar heterojunction organic solar cells
UR - http://www.scopus.com/inward/record.url?scp=85154065345&partnerID=8YFLogxK
U2 - 10.1002/solr.202300267
DO - 10.1002/solr.202300267
M3 - Article
AN - SCOPUS:85154065345
SN - 2367-198X
VL - 7
JO - Solar RRL
JF - Solar RRL
IS - 12
M1 - 2300267
ER -