Luo Zhenghui, Wei Weifei, Ma Ruijie, Ran Guangliu, Jee Min Hun, Chen Zhanxiang, Li Yuxiang, Zhang Wenkai, Woo Han Young, Yang Chuluo
Guangdong Provincial Key Laboratory of New Energy Materials Service Safety, Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518060, China.
Department of Electronic and Information Engineering, Research Institute for Smart Energy (RISE), Guangdong-Hong Kong-Macao (GHM) Joint Laboratory for Photonic-Thermal-Electrical Energy Materials and Devices, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, 999077, China.
Adv Mater. 2024 Oct;36(41):e2407517. doi: 10.1002/adma.202407517. Epub 2024 Aug 13.
High-performance organic solar cells often rely on halogen-containing solvents, which restrict the photovoltaic industry. Therefore, it is imperative to develop efficient organic photovoltaic materials compatible with halogen-free solvents. Herein, a series of benzo[a]phenazine (BP)-core-based small-molecule acceptors (SMAs) achieved through an isomerization chlorination strategy is presented, comprising unchlorinated NA1, 10-chlorine substituted NA2, 8-chlorine substituted NA3, and 7-chlorine substituted NA4. Theoretical simulations highlight NA3's superior orbit overlap length and tight molecular packing, attributed to interactions between the end group and BP unit. Furthermore, NA3 demonstrates dense 3D network structures and a record electronic coupling of 104.5 meV. These characteristics empower the ortho-xylene (o-XY) processed PM6:NA3 device with superior power conversion efficiency (PCE) of 18.94%, surpassing PM6:NA1 (15.34%), PM6:NA2 (7.18%), and PM6:NA4 (16.02%). Notably, the significantly lower PCE in the PM6:NA2 device is attributed to excessive self-aggregation characteristics of NA2 in o-XY. Importantly, the incorporation of D18-Cl into the PM6:NA3 binary blend enhances crystallographic ordering and increases the exciton diffusion length of the donor phase, resulting in a ternary device efficiency of 19.75% (certified as 19.39%). These findings underscore the significance of incorporating new electron-deficient units in the design of efficient SMAs tailored for environmentally benign solvent processing of OSCs.
高性能有机太阳能电池通常依赖含卤溶剂，这限制了光伏产业的发展。因此，开发与无卤溶剂兼容的高效有机光伏材料势在必行。在此，我们展示了一系列通过异构化氯化策略制备的基于苯并[a]吩嗪（BP）核的小分子受体（SMA），包括未氯化的NA1、10-氯取代的NA2、8-氯取代的NA3和7-氯取代的NA4。理论模拟表明，NA3具有优异的轨道重叠长度和紧密的分子堆积，这归因于端基与BP单元之间的相互作用。此外，NA3呈现出密集的三维网络结构和创纪录的104.5 meV电子耦合。这些特性使邻二甲苯（o-XY）处理的PM6:NA3器件具有18.94%的优异功率转换效率（PCE），超过了PM6:NA1（15.34%）、PM6:NA2（7.18%）和PM6:NA4（16.02%）。值得注意的是，PM6:NA2器件中显著较低的PCE归因于NA2在o-XY中的过度自聚集特性。重要的是，将D18-Cl掺入PM6:NA3二元共混物中可增强晶体有序性并增加供体相的激子扩散长度，从而使三元器件效率达到19.75%（认证为19.39%）。这些发现强调了在设计用于有机太阳能电池环境友好型溶剂处理的高效SMA时引入新的缺电子单元的重要性。
