low-energy inverse photoelectron spectrometer for precise analysis of the conduction bands of materials at near ambient pressure conditions

2022 Fiscal Year Final Research Report

• Project/Area Number: 19K22160
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 32:Physical chemistry, functional solid state chemistry, and related fields
• Research Institution: Chiba University
• Principal Investigator: Yoshida Hiroyuki 千葉大学, 大学院工学研究院, 教授 (00283664)
• Project Period (FY): 2019-06-28 – 2023-03-31
• Keywords: 準大気圧電子分光 / 低エネルギー逆光電子分光 / オペランド測定 / 伝導帯

Outline of Final Research Achievements

The energy level of a material governs its photoelectric properties and reactivity. In semiconductors, the unoccupied and valence levels through which electrons and holes transport occur, respectively, determine semiconductor properties. These electron energy levels have been measured by electron spectroscopy in an ultrahigh vacuum. This study realizes the near-ambient pressure measurement of the unoccupied levels, which is the most lagging research area. The method is based on low-energy inverse photoelectron spectroscopy, which was developed by the principal investigator, in which low-energy electrons are irradiated onto a sample, and the light emitted owing to the relaxation of these electrons to the unoccupied level is detected. Since low-energy electrons can only be produced in a high vacuum, differential pumping chambers have been inserted between the electron source and the sample to realize the measurements at near-ambient pressure.

Free Research Field

物性科学、逆光電子分光

Academic Significance and Societal Importance of the Research Achievements

代表者が2012年に開発した低エネルギー逆光電子分光法は、近年発達してきた有機半導体や有機・無機ペロブスカイト材料など機能性材料の空準位を電子線照射による試料損傷なく精密に測定することを可能にし、現在では世界で電子状態の基礎研究や、有機太陽電池や燃料電池などのエネルギー関連の応用研究に利用されている。本研究の成果は、超高真空でしか測定できなかったこの手法を発展させ、準大気圧で測定可能にするものである。実際のデバイスの使用状況に近い状態での試料の観測やそもそも真空では不安定な蒸気圧の高い試料などの測定が可能になるなど、測定可能な試料の種類や状態を飛躍的に拡大することができる。