College of Chemistry and Chemical Engineering/Institute of Polymers and Energy Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang, 330031, P. R. China.
National Engineering Research Center for Carbohydrate Synthesis/Key Lab of Fluorine and Silicon for Energy Materials and Chemistry of Ministry of Education, Jiangxi Normal University, 99 Ziyang Avenue, Nanchang, 330022, P. R. China.
Small. 2023 May;19(18):e2206607. doi: 10.1002/smll.202206607. Epub 2023 Jan 30.
Halogenation of organic semiconductors is an efficient strategy for improving the performance of organic solar cells (OSCs), while the introduction of halogens usually involves complex synthetic process and serious environment pollution problems. Herein, three halogen-free ternary copolymer donors (PCNx, x = 3, 4, 5) based on electron-withdrawing dicyanobenzotriazole are reported. When blended with the Y6, PCN3 with strong interchain interactions results in appropriate crystallinity and thermodynamic miscibility of the blend film. Grazing-incidence wide-angle X-ray scattering measurements indicate that PCN3 has more ordered arrangement and stronger π-π stacking than previous PCN2. Fourier-transform photocurrent spectroscopy and external quantum efficiency of electroluminescence measurements show that PCN3-based OSCs have lower energy loss than PCN2, which leads to their higher open-circuit voltage (0.873 V). The device based on PCN3 reaches power conversion efficiency (PCE) of 15.33% in binary OSCs, one of the highest values for OSCs with halogen-free donor polymers. The PCE of 17.80% and 18.10% are obtained in PM6:PCN3:Y6 and PM6:PCN3:BTP-eC9 ternary devices, much higher than those of PM6:Y6 (16.31%) and PM6:BTP-eC9 (17.33%) devices. Additionally, this ternary OSCs exhibit superior stability compared to binary host system. This work gives a promising path for halogen-free donor polymers to achieve low energy loss and high PCE.
有机半导体的卤化是提高有机太阳能电池 (OSC) 性能的有效策略，然而卤素的引入通常涉及复杂的合成过程和严重的环境污染问题。在此，报道了三种基于吸电子二氰基苯并三唑的无卤三元共聚物给体 (PCNx，x = 3、4、5)。当与 Y6 共混时，具有强链间相互作用的 PCN3 导致共混膜具有适当的结晶度和热力学混溶性。掠入射广角 X 射线散射测量表明，PCN3 具有比之前的 PCN2 更有序的排列和更强的 π-π 堆积。傅里叶变换光电流光谱和电致发光外量子效率测量表明，基于 PCN3 的 OSC 比 PCN2 具有更低的能量损耗，从而导致其具有更高的开路电压 (0.873 V)。基于 PCN3 的器件在二元 OSC 中达到了 15.33%的功率转换效率 (PCE)，这是无卤给体聚合物的 OSC 中最高值之一。在 PM6:PCN3:Y6 和 PM6:PCN3:BTP-eC9 三元器件中，分别获得了 17.80%和 18.10%的 PCE，远高于 PM6:Y6 (16.31%)和 PM6:BTP-eC9 (17.33%)器件。此外，与二元主体系统相比，这种三元 OSC 表现出更好的稳定性。这项工作为无卤给体聚合物实现低能量损耗和高 PCE 提供了有前景的途径。
