TY - JOUR
T1 - Selenium-Functionalized Main-Chain Twisted Molecules with High Melting Points Enable Efficient and Stable Ternary Organic Solar Cells
AU - Wang, Weiping
AU - Liu, Shujuan
AU - Zhou, Yuchen
AU - Cong, Zhiyuan
AU - Wu, Haimei
AU - Gao, Chao
AU - Yang, Zhi
AU - Meng, Zihui
N1 - Publisher Copyright:
© 2026 American Chemical Society
PY - 2026/9/23
Y1 - 2026/9/23
N2 - Although organic solar cells (OSCs) based on Y6 and its derivatives have achieved rapid development, their intrinsically low open-circuit voltage (VOC), which limits the power conversion efficiency (PCE), and the poor long-term stability remain two major obstacles to their application. To address these challenges, two selenium-functionalized main-chain twisted small molecules, i-DA and i-EA, were designed and synthesized. These molecules exhibit strong absorption in the 500−700 nm region and exhibit up-shifted LUMO energy levels, which facilitate cascading energy alignment and enhanced VOC in ternary devices. Notably, they exhibit intrinsically high melting points (Tm) of 312.1 °C (i-DA) and 344.9 °C (i-EA) with large melting enthalpies (ΔHm of 50.02 and 95.61 J g−1), reflecting strong intermolecular cohesion. When incorporated into the PM6:Y6 as the third component, both i-DA and i-EA function as crystallization modulators that optimize the molecular packing and film morphology, leading to improved and more simultaneously balanced hole/electron mobilities. Consequently, the PM6:Y6:i-DA and PM6:Y6:i-EA ternary devices achieve promising PCEs of 19.09% and 19.35%, respectively, with simultaneously enhanced VOC, short-circuit current density (JSC), and fill factor (FF), surpassing the binary device (18.44%). Moreover, the PM6:Y6:i-DA and PM6:Y6:i-EA ternary devices exhibit significantly improved thermal stability (T80 of 840 h and 910 h) compared with the PM6:Y6 control device (T80 of 300 h). The effectiveness of these two molecules is further validated in the D18:L8-BO system, realizing excellent PCEs of 20.33% and 20.50% with i-DA- and i-EA-based ternary devices, respectively. This work demonstrates that high Tm, backbone-twisted small molecular acceptors represent a potential strategy for simultaneously optimizing morphology and charge transport toward high-performance and stable ternary OSCs.
AB - Although organic solar cells (OSCs) based on Y6 and its derivatives have achieved rapid development, their intrinsically low open-circuit voltage (VOC), which limits the power conversion efficiency (PCE), and the poor long-term stability remain two major obstacles to their application. To address these challenges, two selenium-functionalized main-chain twisted small molecules, i-DA and i-EA, were designed and synthesized. These molecules exhibit strong absorption in the 500−700 nm region and exhibit up-shifted LUMO energy levels, which facilitate cascading energy alignment and enhanced VOC in ternary devices. Notably, they exhibit intrinsically high melting points (Tm) of 312.1 °C (i-DA) and 344.9 °C (i-EA) with large melting enthalpies (ΔHm of 50.02 and 95.61 J g−1), reflecting strong intermolecular cohesion. When incorporated into the PM6:Y6 as the third component, both i-DA and i-EA function as crystallization modulators that optimize the molecular packing and film morphology, leading to improved and more simultaneously balanced hole/electron mobilities. Consequently, the PM6:Y6:i-DA and PM6:Y6:i-EA ternary devices achieve promising PCEs of 19.09% and 19.35%, respectively, with simultaneously enhanced VOC, short-circuit current density (JSC), and fill factor (FF), surpassing the binary device (18.44%). Moreover, the PM6:Y6:i-DA and PM6:Y6:i-EA ternary devices exhibit significantly improved thermal stability (T80 of 840 h and 910 h) compared with the PM6:Y6 control device (T80 of 300 h). The effectiveness of these two molecules is further validated in the D18:L8-BO system, realizing excellent PCEs of 20.33% and 20.50% with i-DA- and i-EA-based ternary devices, respectively. This work demonstrates that high Tm, backbone-twisted small molecular acceptors represent a potential strategy for simultaneously optimizing morphology and charge transport toward high-performance and stable ternary OSCs.
KW - backbone-twisted small molecules
KW - long-term stability
KW - organic solar cells
KW - power conversion efficiency
KW - ternary solar cells
UR - https://www.scopus.com/pages/publications/105051298048
U2 - 10.1021/acsami.6c14736
DO - 10.1021/acsami.6c14736
M3 - Article
C2 - 42723414
AN - SCOPUS:105051298048
SN - 1944-8244
VL - 18
SP - 51071
EP - 51082
JO - ACS Applied Materials and Interfaces
JF - ACS Applied Materials and Interfaces
IS - 37
ER -