Yu Jianwei, Chen Peng, Koh Chang Woo, Wang Hang, Yang Kun, Zhou Xin, Liu Bin, Liao Qiaogan, Chen Jianhua, Sun Huiliang, Woo Han Young, Zhang Shiming, Guo Xugang
Department of Materials Science and Engineering and The Shenzhen Key Laboratory for Printed Organic Electronics Southern University of Science and Technology No. 1088, Xueyuan Road Shenzhen Guangdong 518055 China.
Key Laboratory of Flexible Electronics (KLOFE) and Institute of Advanced Materials (IAM) Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM) Nanjing Tech University (NanjingTech) 30 South Puzhu Road Nanjing 211816 China.
Adv Sci (Weinh). 2018 Dec 12;6(2):1801743. doi: 10.1002/advs.201801743. eCollection 2019 Jan 23.
Highly efficient nonfullerene polymer solar cells (PSCs) are developed based on two new phthalimide-based polymers phthalimide-difluorobenzothiadiazole (PhI-ffBT) and fluorinated phthalimide-ffBT (ffPhI-ffBT). Compared to all high-performance polymers reported, which are exclusively based on benzo[1,2-:4,5-']dithiophene (BDT), both PhI-ffBT and ffPhI-ffBT are BDT-free and feature a D-A-D-A type backbone. Incorporating a second acceptor unit difluorobenzothiadiazole leads to polymers with low-lying highest occupied molecular orbital levels (≈-5.6 eV) and a complementary absorption with the narrow bandgap nonfullerene acceptor IT-4F. Moreover, these BDT-free polymers show substantially higher hole mobilities than BDT-based polymers, which are beneficial to charge transport and extraction in solar cells. The PSCs containing difluorinated phthalimide-based polymer ffPhI-ffBT achieve a substantial PCE of 12.74% and a large of 0.94 V, and the PSCs containing phthalimide-based polymer PhI-ffBT show a further increased PCE of 13.31% with a higher of 19.41 mA cm and a larger fill factor of 0.76. The 13.31% PCE is the highest value except the widely studied BDT-based polymers and is also the highest among all benzothiadiazole-based polymers. The results demonstrate that phthalimides are excellent building blocks for enabling donor polymers with the state-of-the-art performance in nonfullerene PSCs and the BDT is not necessary for constructing such donor polymers.
基于两种新型的基于邻苯二甲酰亚胺的聚合物——邻苯二甲酰亚胺-二氟苯并噻二唑（PhI-ffBT）和氟化邻苯二甲酰亚胺-ffBT（ffPhI-ffBT），开发出了高效非富勒烯聚合物太阳能电池（PSC）。与所有已报道的仅基于苯并[1,2-b:4,5-b']二噻吩（BDT）的高性能聚合物相比，PhI-ffBT和ffPhI-ffBT均不含BDT，且具有D-A-D-A型主链。引入第二个受体单元二氟苯并噻二唑可使聚合物具有较低的最高占据分子轨道能级（≈-5.6 eV），并与窄带隙非富勒烯受体IT-4F形成互补吸收。此外，这些不含BDT的聚合物表现出比基于BDT的聚合物高得多的空穴迁移率，这有利于太阳能电池中的电荷传输和提取。含有二氟化邻苯二甲酰亚胺基聚合物ffPhI-ffBT的PSC实现了12.74%的可观光电转换效率（PCE）和0.94 V的大开路电压，而含有邻苯二甲酰亚胺基聚合物PhI-ffBT的PSC表现出进一步提高的13.31%的PCE，具有更高的19.41 mA cm的电流密度和0.76的更大填充因子。13.31%的PCE是除广泛研究的基于BDT的聚合物外的最高值，也是所有基于苯并噻二唑的聚合物中的最高值。结果表明，邻苯二甲酰亚胺是用于制备在非富勒烯PSC中具有先进性能的供体聚合物的优异结构单元，并且构建此类供体聚合物并不需要BDT。
