物理化学学报 >> 2026, Vol. 42 >> Issue (2): 100182.doi: 10.1016/j.actphy.2025.100182

所属专题： 太阳能转化与储存

论文 上一篇    

苯并[a]苯嗪受体的核心氰基化实现高效(19.04%)绿色溶剂加工的二元有机太阳能电池

王震寰1, 韦炜斐1, 马睿杰2, 罗豆3, 陈展翔1, 张君1, 于立扬4, 李刚2, 罗正辉1,*()   

  1. 1 深圳大学材料科学与工程学院, 广东省新能源材料服役安全重点实验室, 深圳市新型信息显示与存储材料重点实验室, 广东 深圳 518060
    2 香港理工大学电子及资讯工程学系, 智慧能源研究院, 粤港澳光热电能材料与器件联合实验室, 香港 999077
    3 香港理工大学应用生物及化学技术学系及智慧能源研究院, 香港 999077
    4 西南交通大学前沿科学研究院, 四川 成都 610031
  • 收稿日期:2025-07-09 修回日期:2025-08-24 录用日期:2025-09-04 发布日期:2025-12-03
  • 通讯作者: Email: zhhuiluo@szu.edu.cn (罗正辉)

Core cyanation of benzo[a]phenazine acceptor enables 19.04% binary organic solar cells with green solvent compatibility

Zhenhuan Wang1, Weifei Wei1, Ruijie Ma2, Dou Luo3, Zhanxiang Chen1, Jun Zhang1, Liyang Yu4, Gang Li2, Zhenghui Luo1,*()   

  1. 1 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, Guangdong Province, China
    2 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, Hong Kong 999077, China
    3 Department of Applied Biology and Chemical Technology and Research Institute for Smart Energy, The Hong Kong Polytechnic University, Hong Kong 999077, China
    4 Research Institute of Frontier Science, Southwest Jiaotong University, Chengdu 610031, Sichuan Province, China
  • Received:2025-07-09 Revised:2025-08-24 Accepted:2025-09-04 Published:2025-12-03
  • Contact: Email: zhhuiluo@szu.edu.cn (Zhenghui Luo)

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摘要：

氰基化作为一种有效的分子工程策略，能够通过协同的电子效应和空间效应精确调控有机半导体的前线轨道能级与超分子组装行为。本研究设计并合成了一种新型氰基取代的小分子受体NA8，其基于苯并[a]苯嗪核心结构，利用氰基的高极性和线性构型来增强分子间作用并促进电荷分离。理论与实验结果表明，氰基取代在削弱分子内电荷转移作用(引起吸收蓝移)的同时，显著提升了分子间作用和堆积行为，使NA8表现出相对于中心核无氰基取代的对比分子NA1更高的结晶相干长度。受益于这一分子层面的优化，采用绿色溶剂邻二甲苯制备的PM6:NA8器件实现了19.04%的优异光电转换效率(对比PM6 : NA1的15.14%)，其性能提升主要归因于更高的短路电流密度(27.35 mA cm−2)和填充因子(78.3%)。进一步的原子力显微镜(AFM)、掠入射广角X射线衍射(GIWAXS)和瞬态吸收光谱(TAS)表征证实，NA8基器件的优异性能源于更理想的相分离形貌、更高的载流子迁移率以及更快的激子解离过程。尽管开路电压略有降低(0.889 V vs. 0.914 V)，这与氰基引入后C–C键振动增强所致的重组能升高相符。综上，核心氰基化为开发兼具高效率与非卤代溶剂加工兼容性的受体材料提供了一条有效途径，并为新一代有机光伏的分子设计提供了参考。

关键词: 小分子受体, 有机太阳能电池, 光电转换效率, 氰基取代, 分子间作用

Abstract:

The design of high-performance small-molecule acceptors (SMAs) for organic solar cells (OSCs) remains a central challenge, particularly under the growing demand for environmentally friendly processing conditions. While halogenation has been widely employed to optimize electronic structures and molecular packing, its reliance on toxic halogenated solvents and the limited tunability of intermolecular interactions highlight the need for alternative strategies. In this context, core functionalization with cyano (CN) groups provides a unique opportunity, as the CN unit combines strong electron-withdrawing ability, high polarity, and linear geometry, potentially offering synergistic regulation of both optoelectronic properties and supramolecular assembly. However, systematic studies on core cyanation remain scarce, and its precise role in balancing charge transfer, molecular ordering, and energy loss in OSCs has not been thoroughly clarified.Here, we report a cyano-functionalized benzo[a]phenazine (BP)-core SMA, denoted as NA8, to explore how core cyanation influences device performance. The introduction of the CN group reduces the intramolecular charge transfer, resulting in a blue-shifted absorption and a slightly enlarged optical bandgap compared with the non-cyanated analogue NA1. Despite this apparent drawback, NA8 demonstrates superior molecular packing, as evidenced by grazing-incidence wide-angle X-ray scattering (GIWAXS) measurements showing a crystalline coherence length more than twice that of NA1 (101.3 Å vs. 44.6 Å). This improvement originates from the significantly enhanced dipole moment of NA8 (4.26 D vs. 2.21 D for NA1), which facilitates stronger electrostatic and noncovalent interactions (e.g., S···N and H···N contacts), thereby stabilizing more ordered packing motifs.At the blend-film level, atomic force microscopy (AFM) reveals that PM6:NA8 exhibits a rougher yet more clearly phase-separated morphology compared with PM6:NA1, providing continuous transport pathways. Photo-CELIV measurements confirm higher carrier mobility (2.36 × 10−4 cm2 V−1 s−1 vs. 1.29 × 10−4 cm2 V−1 s−1), while transient absorption spectroscopy shows faster exciton dissociation and reduced bimolecular recombination. Together, these synergistic effects explain why the PM6:NA8 device achieves an outstanding power conversion efficiency of 19.04% using non-halogenated o-xylene, compared with 15.14% for PM6:NA1. The improvement primarily arises from the significantly enhanced short-circuit current density (27.35 mA cm−2) and fill factor (78.3%), while the open-circuit voltage is only moderately reduced (0.889 V vs. 0.914 V) due to increased reorganization energy associated with C–C bond vibrations in the CN-substituted BP core. Our study identifies core cyanation as a powerful molecular engineering strategy to concurrently tune energy levels, strengthen molecular packing, and optimize nanoscale morphology, providing valuable design guidance for next-generation organic photovoltaics.

Key words: Small molecular acceptor, Organic solar cells, Power conversion efficiency, Cyano substitution, Molecular interaction