Li Guanghao, Xu Chunyu, Luo Zhenghui, Ning Weimin, Liu Xiaohui, Gong Shaolong, Zou Yang, Zhang Fujun, Yang Chuluo
Hubei Key Laboratory on Organic and Polymeric Optoelectronic Materials, Department of Chemistry, Wuhan University, Wuhan 430072, China.
Shenzhen Key Laboratory of Polymer Science and Technology, College of Materials Science and Engineering, Shenzhen University, Shenzhen 518060, China.
ACS Appl Mater Interfaces. 2020 Mar 18;12(11):13068-13076. doi: 10.1021/acsami.9b22093. Epub 2020 Mar 9.
Novel cores for high performance nonfullerene acceptors (NFAs) remain to be developed. In this work, two new n-type nitrogen-containing organic heterocyclic NFAs, namely, BDTN-BF and BDTN-Th, were designed and synthesized based on a new seven fused-ring core (BDTN) with two different end-capping groups. As a result, BDTN-BF possessed similar absorption spectra in solution and solid state to BDTN-Th, but a slightly higher maximum molar extinction coefficient. Manufacturing the polymer solar cells with PM6 as the donor, the photovoltaic performance of BDTN-BF and BDTN-Th was investigated. The PM6:BDTN-BF-based device achieved the highest power conversion efficiency (PCE) of 11.54% with a high of 20.20 mA cm, a fill factor (FF) of 61.46%, and a large of 0.93 V, and the energy loss () was calculated to be 0.48 eV. Comparatively, the PM6:BDTN-Th-based device achieved the maximum PCE value of only 3.53% because of inadequate and FF. The higher and FF for the PM6:BDTN-BF-based device was mainly due to the effective electron transfer from PM6 to BDTN-BF, more balanced μ/μ, higher electron mobility of the neat film, better charge collection and dissociation efficiency, and more favorable morphology. These results demonstrate that the acceptors with nearly identical absorption spectra could result in a significant difference in photovoltaic performance, which stress the importance of end-capping units. Furthermore, few NFA-based devices achieve large and high simultaneously as one based on PM6:BDTN-BF, indicating that nitrogen hybridization of NFAs may be an efficient strategy to realize high and balanced and .
高性能非富勒烯受体（NFA）的新型核心仍有待开发。在这项工作中，基于具有两个不同封端基团的新型七稠环核心（BDTN），设计并合成了两种新型n型含氮有机杂环NFA，即BDTN-BF和BDTN-Th。结果表明，BDTN-BF在溶液和固态中的吸收光谱与BDTN-Th相似，但最大摩尔消光系数略高。以PM6作为给体制备聚合物太阳能电池，研究了BDTN-BF和BDTN-Th的光伏性能。基于PM6:BDTN-BF的器件实现了11.54%的最高功率转换效率（PCE），具有20.20 mA cm的高电流密度、61.46%的填充因子（FF）和0.93 V的大开路电压（Voc），计算得出的能量损失（Eloss）为0.48 eV。相比之下，基于PM6:BDTN-Th的器件由于电流密度和填充因子不足，仅实现了3.53%的最大PCE值。基于PM6:BDTN-BF的器件具有更高的电流密度和填充因子，主要是由于从PM6到BDTN-BF的有效电子转移、更平衡的空穴迁移率/电子迁移率（μh/μe）、纯膜更高的电子迁移率、更好的电荷收集和解离效率以及更有利的形貌。这些结果表明，具有几乎相同吸收光谱的受体可能导致光伏性能的显著差异，这突出了封端单元的重要性。此外，很少有基于NFA的器件能像基于PM6:BDTN-BF的器件那样同时实现大的开路电压和高的电流密度，这表明NFA的氮杂化可能是实现高且平衡的开路电压和电流密度的有效策略。
