Deterioration of Li-doped phenanthroline-based charge generation layer for tandem organic light-emitting diodes

Autor: Ki Ju Kim, Sunwoo Kang, Taekyung Kim
Jazyk: angličtina
Rok vydání: 2024
Předmět:
Zdroj: Journal of Information Display, Pp 1-10 (2024)
Druh dokumentu: article
ISSN: 15980316
2158-1606
1598-0316
DOI: 10.1080/15980316.2024.2356848
Popis: Understanding the deterioration of the charge generation layer (CGL) is an uprising issue for efficient and stable tandem organic light-emitting diodes. Here, we comprehensively investigated the change in the electrical characteristics of Li-doped CGLs according to different stress conditions and compared the stability of Li diffusion in two phenanthroline-based electron transport materials. Through current density–voltage and capacitance-frequency measurements, it was revealed that electrical stress and thermal stress affect CGL’s electrical properties differently. Moreover, the exponential trap distribution model analysis informed that the Li diffusion is expedited toward narrowing depletion width in the CGL. Diffusion of Li and thermal effect to the diffusion was experimentally observed by X-ray photoelectron spectroscopy (XPS) depth profiling. We also evaluated variations in the operating voltage of tandem devices that differed only in nCGL. Overall, Li diffusion occurs more favorably in sparse Bphen film with weak binding energy rather than closely packed BPPB film with strong binding energy, which highlights that atomic geometry and morphological characteristics are crucial for the stability of tandem devices.
Databáze: Directory of Open Access Journals