Li Shaoxian, Nishikubo Ryosuke, Saeki Akinori
Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
Innovative Catalysis Science Division (ICS), Institute for Open and Transdisciplinary Research Initiatives (OTRI), Osaka University, 1-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
ACS Omega. 2024 Jun 13;9(25):26951-26962. doi: 10.1021/acsomega.3c09977. eCollection 2024 Jun 25.
This article reports a purely experiment-based method to evaluate the time-dependent charge carrier mobilities in thin-film organic solar cells (OSCs) using simultaneous charge extraction by linearly increasing the voltage (CELIV) and time-resolved microwave conductivity (TRMC) measurements. This method enables the separate measurement of electron mobility (μ) and hole mobility (μ) in a metal-insulator-semiconductor (MIS) device. A slope-injection-restoration voltage profile for MIS-CELIV is also proposed to accurately determine the charge densities. The dynamic behavior of μ and μ is examined in five bulk heterojunction (BHJ) OSCs of polymer:fullerene (P3HT:PCBM and PffBT4T:PCBM) and polymer:nonfullerene acceptor (PM6:ITIC, PM6:IT4F, and PM6:Y6). While the former exhibits fast decays of μ and μ, the latter, in particular, PM6:IT4F and PM6:Y6, exhibits slow decays. Notably, the high-performing PM6:Y6 demonstrates both a balanced mobility (μ/μ) of 1.0-1.1 within 30 μs and relatively large CELIV-TRMC mobility values among the five BHJs. The results exhibit reasonable consistency with a high fill factor. The proposed new CELIV-TRMC technique offers a path toward a comprehensive understanding of dynamic mobility and its correlation with the OSC performance.
本文报道了一种基于实验的纯方法，用于通过线性增加电压同时进行电荷提取（CELIV）和时间分辨微波电导率（TRMC）测量来评估薄膜有机太阳能电池（OSC）中随时间变化的电荷载流子迁移率。该方法能够在金属-绝缘体-半导体（MIS）器件中分别测量电子迁移率（μ）和空穴迁移率（μ）。还提出了一种用于MIS-CELIV的斜率注入-恢复电压曲线，以准确确定电荷密度。在聚合物：富勒烯（P3HT:PCBM和PffBT4T:PCBM）以及聚合物：非富勒烯受体（PM6:ITIC、PM6:IT4F和PM6:Y6）的五个体异质结（BHJ）OSC中研究了μ和μ的动态行为。虽然前者表现出μ和μ的快速衰减，但后者，特别是PM6:IT4F和PM6:Y6，表现出缓慢衰减。值得注意的是，高性能的PM6:Y6在30μs内表现出1.0-1.1的平衡迁移率（μ/μ），并且在五个BHJ中具有相对较大的CELIV-TRMC迁移率值。结果与高填充因子表现出合理的一致性。所提出的新的CELIV-TRMC技术为全面理解动态迁移率及其与OSC性能的相关性提供了一条途径。
