Stability of Nonfullerene Organic Solar Cells: from Built-in Potential and Interfacial Passivation Perspectives

Yiwen Wang, Weixia Lan, Ning Li, Zhaojue Lan, Zhen Li, Jingnan Jia, Fu Rong ZHU*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

45 Citations (Scopus)

Abstract

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 report our effort to understand the stability of nonfullerene OSCs, made with the binary blend poly[(2,6-(4, 8-bis(5-(2-ethylhexyl)thiophen-2-yl)-benzo[1,2-b:4,5-b′]dithiophene))-alt-(5,5-(1′,3′-di-2-thienyl-5′,7′-bis(2-ethylhexyl)benzo[1′,2′-c:4′,5′-c′] dithiophene-4,8-dione)] (PBDB-T):3,9- bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)- dithieno[2,3-d:2′,3′-d′]-s-indaceno[1,2-b:5,6-b′] dithiophene (ITIC) system. It shows that a continuous vertical phase separation process occurs, 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 (V 0 ) in the regular configuration PBDB-T:ITIC OSCs, due to the interfacial reaction between the poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) hole transporting layer and ITIC acceptor, is one of the reasons responsible for the performance deterioration. The reduction in V 0 , caused by an inevitable reaction at the ITIC/PEDOT:PSS interface in the OSCs, can be suppressed by introducing a MoO 3 interfacial passivation layer. Retaining a stable and high V 0 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.

Original languageEnglish
Article number1900157
JournalAdvanced Energy Materials
Volume9
Issue number19
DOIs
Publication statusPublished - 16 May 2019

Scopus Subject Areas

  • Renewable Energy, Sustainability and the Environment
  • Materials Science(all)

User-Defined Keywords

  • built-in potential
  • charge extraction
  • interfacial passivation
  • stability of nonfullerene organic solar cells
  • vertical phase separation

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