title: High Spatial Resolution Laser Desorption/Ionization Mass Spectrometry Imaging of Organic Layers in an Organic Light-Emitting Diode.
abstract: To improve the durability of organic materials in electronic devices, an analytical method that can obtain information about the molecular structure directly from specific areas on a device is desired. For this purpose, laser desorption/ionization mass spectrometry imaging (LDI-MSI) is one of the most promising methods. The high spatial resolution stigmatic LDI-MSI with MULTUM-IMG2 in the direct analysis of organic light-emitting diodes was shown to obtain a detailed mass image of organic material in the degraded area after air exposure. The mass image was observed to have a noticeably improved spatial resolution over typical X-ray photoelectron spectroscopy, generally used technique in analysis of electronic devices. A prospectivem/zwas successfully deduced from the high spatial resolution MSI data. Additionally, mass resolution and accuracy using a spiral-orbit TOF mass spectrometer, SpiralTOF, were also investigated. The monoisotopic mass for the main component,N,N'-di-1-naphthalenyl-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine (m/z588), was measured with a mass resolution of approximately 80,000 and a mass error of about 5 mDa using an external calibrant. This high mass resolution and accuracy data successfully deduced a possible elemental composition of partially remained material in the degraded area, C36H24, which was determined as anthracene, 9-[1,1'-biphenyl]-4-yl-10-(2-naphthalenyl) by combining structural information with high-energy CID data. The high spatial resolution of 1 μm in LDI-MSI along with high mass resolution and accuracy could be useful in obtaining molecular structure information directly from specific areas on a device, and is expected to contribute to the evolution of electrical device durability.
authors.affiliation: Asahi Glass Co., Ltd.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Tachibana
authors.affiliation: Asahi Glass Co., Ltd.
authors.forename: Yoji
authors.initials: Y
authors.lastname: Nakajima
authors.affiliation: Asahi Glass Co., Ltd.
authors.forename: Tsuguhide
authors.initials: T
authors.lastname: Isemura
authors.affiliation: Asahi Glass Co., Ltd.
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Yamamoto
authors.affiliation: JEOL Ltd.
authors.forename: Takaya
authors.initials: T
authors.lastname: Satoh
authors.affiliation: Project Research Center for Fundamental Sciences, Graduate School of Science, Osaka University.
authors.forename: Jun
authors.initials: J
authors.lastname: Aoki
authors.affiliation: Project Research Center for Fundamental Sciences, Graduate School of Science, Osaka University.
authors.forename: Michisato
authors.initials: M
authors.lastname: Toyoda
keywords: MULTUM; OLED; SpiralTOF; laser desorption/ionization mass spectrometry imaging; mass accuracy