Inverse Photoemission Spectroscopy for Direct Measurement of Energy Gaps in OLED Materials
일 시 : 2021년 12월 01일 수요일 16:30
연 사 : 박 용 섭 교수 (경희대학교 물리학과)
장 소 : 자연과학관 747호 & 온라인 (https://us02web.zoom.us/j/81628441938, 회의 ID: 816 2844 1938)
HOST : 정 문 석 교수님
초 록
We measured the transport energy gaps of several organic electronic materials including pentacene and C60 by the combination of ultraviolet photoemission spectroscopy for the highest occupied molecular orbital measurements and inverse photoemission spectroscopy for lowest unoccupied molecular orbitals. In particular, we optimized the performance of low-energy inverse photoemission (LEIPS) using an in-vacuo parabolic mirror. With the improved LEIPS sensitivity, we were able to follow the evolution of the transport gap values as a function of organic film thickness on substrates with different surface work functions. We will describe the details of the LEIPS optimization and discuss the implication of the transport gap evolution on the carrier injection efficiency of the organic/substrate interface.