Xue Yung-Jing, Wang Yu-Chieh, Lu Han-Cheng, Tsai Chia-Lin, Lu Chia-Fang, Yeh Li-Lun, Cheng Yen-Ju
Department of Applied Chemistry, National Yang Ming Chiao Tung University, 1001 University Road, Hsinchu, Taiwan 30010.
Center for Emergent Functional Matter Science, National Yang Ming Chiao Tung University, 1001 University Road, Hsinchu, Taiwan 30010.
ACS Appl Mater Interfaces. 2024 Oct 23;16(42):57481-57490. doi: 10.1021/acsami.4c11466. Epub 2024 Oct 14.
In this work, we designed two nitrogen-bridged fluorene-based heptacyclic FNT and nonacyclic FNTT ladder-type structures, which were constructed by one-pot palladium-catalyzed Buchwald-Hartwig amination. FNT and FNTT were further end-capped by FIC acceptors to form two FNT-FIC and FNTT-FIC non-fullerene acceptors (NFAs), respectively. The two NFAs exhibit more red-shifted absorption and higher crystallinity compared to those of the corresponding carbon-bridged FCT-FIC and FCTT-FIC counterparts. Grazing incidence wide-angle X-ray scattering (GIWAXS) measurements reveal that the 2-butyloctyl groups on the nitrogen in the convex region of FNT-FIC interdigitate with the dioctyl groups on the fluorene in the concave region of another FNT-FIC, resulting in a lamellar packing structure with a spacing of 13.27 Å. As a consequence, the PM6:FNT-FIC (1:1 wt %) device achieved a power conversion efficiency (PCE) of only 6.60%, primarily due to the highly crystalline nature of FNT-FIC, which induced significant phase separation between PM6 and FNT-FIC in the blended film. However, FNTT-FIC, featuring 2-butyloctyl groups positioned on the nitrogen within the concave region of its curved skeleton, exhibits improved donor-acceptor miscibility, thereby promoting a more favorable morphology. As a result, the PM6:FNTT-FIC (1:1.2 wt %) device exhibited a higher PCE of 12.15% with an exceptional of 0.96 V. This research demonstrates that placing alkylamino moieties within the concave region of curved A-D-A NFAs leads to a better molecular design.
在本工作中，我们设计了两种氮桥连芴基七环FNT和九环FNTT阶梯型结构，它们通过一锅法钯催化的布赫瓦尔德-哈特维希胺化反应构建而成。FNT和FNTT进一步用FIC受体封端，分别形成两种FNT-FIC和FNTT-FIC非富勒烯受体（NFA）。与相应的碳桥连FCT-FIC和FCTT-FIC相比，这两种NFA表现出更红移的吸收和更高的结晶度。掠入射广角X射线散射（GIWAXS）测量表明，FNT-FIC凸区氮上的2-丁基辛基与另一个FNT-FIC凹区芴上的二辛基相互交错，形成了层间距为13.27 Å的层状堆积结构。因此，PM6:FNT-FIC（1:1重量%）器件的功率转换效率（PCE）仅为6.60%，主要是由于FNT-FIC的高结晶性质，导致共混膜中PM6和FNT-FIC之间出现明显的相分离。然而，FNTT-FIC在其弯曲骨架的凹区内氮上带有2-丁基辛基，表现出改善的供体-受体混溶性，从而促进了更有利的形态。结果，PM6:FNTT-FIC（1:1.2重量%）器件表现出更高的PCE，为12.15%，开路电压高达0.96 V。本研究表明，将烷基氨基部分置于弯曲的A-D-A NFA的凹区内可实现更好的分子设计。
