报告题目：Stability of Nonfullerene Organic Solar Cells

报告人姓名：朱福荣教授（香港浸会大学）

报告时间：2019年7月19日, 10:30-12：00

报告地点：延长校区 平板显示中心二楼大会议室

承办单位：新型显示技术及应用集成教育部重点实验室

报告摘要：Remarkable progress has been made in the development of high efficiency solution-processable nonfullerene organic solar cells (OSCs). However, the effect of the vertical stratification of bulk heterojunction (BHJ) on the efficiency and stability of nonfullerene OSCs is not fully understood yet. In this work, we found that a continuous vertical phase separation process occurred, forming a PBDB-T-rich top surface and an ITIC-rich bottom surface in PBDB-T:ITIC BHJ during the aging period. A gradual decrease in the built-in potential (V₀) in the regular configuration PBDB-T:ITIC OSCs, due to the interfacial reaction between PEDOT:PSS hole transporting layer and ITIC acceptor, is one of the reasons responsible for the performance deterioration. The reduction in V₀, caused by an inevitable reaction at the ITIC/PEDOT:PSS interface in the OSCs can be suppressed by introducing an MoO₃ interfacial passivation layer, as shown in Fig. 1. Retaining a stable and high V₀ across the BHJ through interfacial modification and device engineering, e.g., as seen in the inverted PBDB-T:ITIC OSCs, is a prerequisite for efficient and stable operation of nonfullerene OSCs [1,2].

Fig. 1 The normalized V_OC, measured for an inverted PBDB-T:ITIC OSC (control) and regular configuration cells with different hole transporting layers, as a function of the aging time.

[1] Y.W. Wang, W.X. Lan, N. Li, Z.J. Lan, Z. Li, J.N. Jia and F.R. Zhu, Adv. Energy Mater. (2019) 1900157.

[2] Y.W. Wang, B. Wu, Z.H. Wu, Z.J. Lan, Y.F. Li, M.J. Zhang, F.R. Zhu, J. Phys. Chem. Lett. 8 (2017) 5264-5271.