Time-Resolved Chemical Mapping in Light-Emitting Electrochemical Cells

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• 作者：Mohammad Javad Jafari ; Jiang LiuIsak Engquist ; Thomas Ederth
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2017
• 出版时间：January 25, 2017
• 年：2017
• 卷：9
• 期：3
• 页码：2747-2757
• 全文大小：719K
• ISSN：1944-8252

文摘

An understanding of the doping and ion distributions in light-emitting electrochemical cells (LECs) is required to approach a realistic conduction model which can precisely explain the electrochemical reactions, p–n junction formation, and ion dynamics in the active layer and to provide relevant information about LECs for systematic improvement of function and manufacture. Here, Fourier-transform infrared (FTIR) microscopy is used to monitor anion density profile and polymer structure in situ and for time-resolved mapping of electrochemical doping in an LEC under bias. The results are in very good agreement with the electrochemical doping model with respect to ion redistribution and formation of a dynamic p–n junction in the active layer. We also physically slow ions by decreasing the working temperature and study frozen-junction formation and immobilization of ions in a fixed-junction LEC device by FTIR imaging. The obtained results show irreversibility of the ion redistribution and polymer doping in a fixed-junction device. In addition, we demonstrate that infrared microscopy is a useful tool for in situ characterization of electroactive organic materials.