INTERFACE INVESTIGATIONS OF CHEMICAL AND ELECTRONIC INTERACTIONS BETWEEN ALKALI METALS AND ORGANIC SEMICONDUCTOR MATERIALS

Abstract

To realize the rational design of the potential anode materials, it is significant to systematically understand the interfacial reactions during the storage process of alkali metals. Here, we have investigated the alkali interactions on organic functional groups in the model systems of perylene-3,4,9, 10-tetracarboxylicdianhydride (PTCDA), perylene-3,4,9,10-tetracarboxylic diimide (PTCDI), pristine and fluorinated copper(II) phthalocyanine (CuPc). The chemical and electronic structure evolutions have been probed with in-situ X-ray photoemission spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), near-edge X-ray absorption fine structure (NEXAFS) spectroscopy and density functional theory (DFT) calculations. For PTCDA, the carbonyl groups and the related charge redistribution on the PTCDA perylene are essential for Li/Na storage. For PTCDI, alkali metal atoms can replace the hydrogen atoms in the imide groups. By comparison of lithium interactions on F16CuPc and CuPc, anchoring of Li atoms at the outer aza bridge N sites is promoted by Li−F interaction on F16CuPc.