TY - JOUR
T1 - Impact of meta- and para-Direction External Side Chains in Y-Series Acceptors on the Molecular Packing and Charge Carrier Dynamics of Organic Photovoltaics
AU - Park, Changwoo
AU - Xuyao, Song
AU - Ham, Gayoung
AU - Bae, Kihyun
AU - Lim, Chulhee
AU - Park, Sanghun
AU - Kim, Young Yong
AU - Lee, Junyeong
AU - Jo, Sungjin
AU - Kwon, Soon Ki
AU - Kim, Bumjoon J.
AU - Kim, Yun Hi
AU - Cha, Hyojung
N1 - Publisher Copyright:
© 2024 American Chemical Society.
PY - 2025/1/29
Y1 - 2025/1/29
N2 - The side-chain directions in nonfullerene acceptors (NFAs) strongly influence the intermolecular interactions in NFAs; however, the influence of these side chains on the morphologies and charge carrier dynamics of Y6-based acceptors remains underexplored. In this study, we synthesize four distinct Y6-based acceptors, i.e., meta-HOP-Y6-F (mF), meta-HOP-Y6-Cl (mCl), para-HOP-Y6-F (pF), and para-HOP-Y6-Cl (pCl), with outer side chains of alkoxy-2-ethylhexyl attached at the meta or para positions. Devices containing the meta-position acceptors blended with the polymer donor PM6 achieve power conversion efficiencies (PCEs) at least 1.27-fold higher than those of devices containing para-position acceptors. The enhanced performance can be attributed to the formation of donor-acceptor domains that are advantageous for charge carrier generation, transport, and collection. This is due to variations in phase aggregation that result from steric hindrance effects at the meta- and para-position acceptors. As a result, meta-position acceptors with lower steric hindrance improved π-π and lamellar stacking, whereas the para-position acceptors encountered excessive steric hindrance, reducing their photovoltaic efficiencies. Additionally, the meta-position acceptors demonstrate long charge carrier lifetimes, which suppress recombination in the charge transfer state and promote efficient charge separation. These results underline the critical role of side-chain direction in optimizing Y6-based acceptors for improving photovoltaic performance.
AB - The side-chain directions in nonfullerene acceptors (NFAs) strongly influence the intermolecular interactions in NFAs; however, the influence of these side chains on the morphologies and charge carrier dynamics of Y6-based acceptors remains underexplored. In this study, we synthesize four distinct Y6-based acceptors, i.e., meta-HOP-Y6-F (mF), meta-HOP-Y6-Cl (mCl), para-HOP-Y6-F (pF), and para-HOP-Y6-Cl (pCl), with outer side chains of alkoxy-2-ethylhexyl attached at the meta or para positions. Devices containing the meta-position acceptors blended with the polymer donor PM6 achieve power conversion efficiencies (PCEs) at least 1.27-fold higher than those of devices containing para-position acceptors. The enhanced performance can be attributed to the formation of donor-acceptor domains that are advantageous for charge carrier generation, transport, and collection. This is due to variations in phase aggregation that result from steric hindrance effects at the meta- and para-position acceptors. As a result, meta-position acceptors with lower steric hindrance improved π-π and lamellar stacking, whereas the para-position acceptors encountered excessive steric hindrance, reducing their photovoltaic efficiencies. Additionally, the meta-position acceptors demonstrate long charge carrier lifetimes, which suppress recombination in the charge transfer state and promote efficient charge separation. These results underline the critical role of side-chain direction in optimizing Y6-based acceptors for improving photovoltaic performance.
KW - carrier lifetimes
KW - charge carrier dynamics
KW - molecular packing
KW - nonfullerene acceptors
KW - side-chain directions
UR - http://www.scopus.com/inward/record.url?scp=85213571522&partnerID=8YFLogxK
U2 - 10.1021/acsami.4c17649
DO - 10.1021/acsami.4c17649
M3 - Article
AN - SCOPUS:85213571522
SN - 1944-8244
VL - 17
SP - 6648
EP - 6658
JO - ACS Applied Materials and Interfaces
JF - ACS Applied Materials and Interfaces
IS - 4
ER -