Revival of Insulating Polyethylenimine by Creatively Carbonizing with Perylene into Highly Crystallized Carbon Dots as the Cathode Interlayer for High-Performance Organic Solar Cells

• Published in: ACS applied materials & interfaces Vol. 14; no. 1; pp. 1280 - 1289
• Main Authors: Dong, Yiman, Yu, Runnan, Zhao, Biao, Gong, Yongshuai, Jia, Haoran, Ma, Zongwen, Gao, Huaizhi, Tan, Zhan’ao
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 12-01-2022
• Subjects: Energy, Environmental, and Catalysis Applications; electron transporting layer; cathode interlayer; carbon dot; inverted organic solar cell; interface engineering
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/acsami.1c23494

The development of new electron transporting layer (ETL) materials to improve the charge carrier extraction and collection ability between cathode and the active layer has been demonstrated to be an effective approach to enhance the photovoltaic performance of organic solar cells (OSCs). Herein, water-soluble carbon dots (CDs) as ETL material have been creatively synthesized by a vigorous chemical reaction between polyethylenimine (PEI) and 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) via a simple one-step hydrothermal method. Taking full advantage of the high electron transfer property of PTCDA and the work function (W F) reduction ability of PEI, CD gained high electron mobility due to its large π-conjugated area and reduced the W F of indium tin oxide (ITO) by 0.75 eV. As for the photovoltaic performance of devices, inverted OSCs based on CDs have achieved a high power conversion efficiency (PCE) of 17.35%, exhibiting no burn-in effect with no reduction in PCE after more than 4000 h of storage. The successful application of CDs in OPV has developed a new avenue for designing efficient ETL materials that benefits the photovoltaic performance of OSCs.