Development of a julolidine-based interfacial modifier for efficient inverted polymer solar cells. Issue 130 (18th December 2015)

• Record Type: Journal Article
• Authors: Choi, Eun Young; Nam, So Youn; Song, Chang Eun; Kong, Ki-jeong; Lee, Changjin; Jung, In Hwan; Yoon, Sung Cheol
• Is Part Of: RSC advances. Volume 5:Issue 130(2015)
• Page Start: 107540
• Page End: 107546
• Publication Date: 2015-12-18
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c5ra21087a
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : We demonstrate the julolidine moiety is an excellent electron donating building block for developing interfacial modifiers to improve the ZnO surface properties in inverted polymer solar cells. Abstract : To enhance the performance of inverted polymer solar cells (PSCs), we have designed and synthesized interfacial modifiers (IMs) which provide better surface properties for the ZnO layer. The synthesized IMs were composed of electron donating and accepting parts. Julolidine or diethyl aniline was used as a donor part, and cyano acrylic acid as an acceptor part. The julolidine-basedB1 material exhibited a much stronger dipole moment of 9.86 D than diethyl aniline-basedB2 (9.17 D), and the water contact angle of the ZnO surface treated withB1 (65.3°) was much larger than that withB2 (39.8°). These julolidine effects were much more powerful than diethyl aniline: the julolidine moiety significantly decreased the hydrophilicity of the ZnO surface and its work function (WF). The inverted devices with the configuration of ITO/ZnO/IMs (B1 orB2 )/PTB7-Th:PC71 BM/MoO3 /Ag were fabricated and the photovoltaic properties were investigated. BothB1 andB2 worked well as IMs, butB1 -treated devices exhibited a much higher power conversion efficiency of 8.35% thanB2 -treated devices (7.80%).B1 treatment on ZnO effectively reduced series resistance and leakage current in the devices due to the julolidine effects. We believe that julolidine is an excellent electron donating building block for IMs in inverted PSCs and our approach can be applied to other IM systems universally to improve photovoltaic performance.