报告题目：Stability of Nonfullerene Organic Solar Cells
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 VOC, 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.
 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.
 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.