A strategy of synergistic optimization: gold and lithium co-doped vanadium oxide as a hole-injection layer for high-performance OLEDs. Issue 40 (21st September 2022)

• Record Type: Journal Article
• Authors: Zhang, Han; Zhu, Wenqing; Huang, Lu; Yi, Chen; Chen, Ruilin; Chen, Yipeng; Li, Jun
• Is Part Of: Journal of materials chemistry. Volume 10:Issue 40(2022)
• Page Start: 15000
• Page End: 15007
• Publication Date: 2022-09-21
• Subjects: Materials -- Periodicals; Chemistry, Analytic -- Periodicals; Optical materials -- Research -- Periodicals; Electronics -- Materials -- Research -- Periodicals; 543.0284
• DOI: 10.1039/d2tc03121c
• Languages: English
• ISSNs: 2050-7526

Abstract

Abstract : A gold and lithium co-doping strategy has been employed to fabricate a VO x hole-injection layer for a matched energy level alignment between the ITO anode and TAPC (hole-transport layer) and improved performance of OLEDs. Abstract : The hole-injection layer (HIL) plays a critical role in the efficiency and stability of organic light-emitting diodes (OLEDs). However, inorganic HIL materials, such as transition metal oxides (TMOs), usually suffer the problems of low conductivity and mismatched work function at ITO/hole-transport layer (HTL) interfaces, which limits the hole-injection in OLEDs. In this paper, a gold (Au) and lithium (Li) co-doping strategy has been employed to fabricate a vanadium oxide (VO x ) HIL through solution processing at low temperature for improving device performance. Compared to non-doped VO x and Au-doped VO x films, co-doping with an optimal molar ratio of Au and Li endows the VO x films with both higher electrical conductivity and proper work function matching with the ITO anode and HTL, which leads to efficient hole-injection and improved carrier balance in the device with the Au and Li co-doped VO x (Au, Li:VO x ) HIL. As a result, the device with the Au, Li:VO x HIL shows a peak power efficiency of 50.2 lm W −1 and a maximum external quantum efficiency (EQE) of 19.9%, which are superior to those of the counterpart with the VO x HIL (34.4 lm W −1 and 18.1%). Meanwhile, the device shows distinguished stability. This work indicates that Au and Li co-doping is an effective method to obtain an efficient VO x HIL with excellent hole-injection ability, which provides a promising avenue to enhance OLED performance.