A novel intermediate connector with improved charge generation and separation for large-area tandem white organic lighting devices

摘要

An intermediate connector (IC) consisting of lithium (Li) doped 4,7-diphenyl-1,10-phenanthroline (BPhen)/Al/tetrafluoro-tetracyanoquinodimethane (F-4-TCNQ)/1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile (HAT-CN) is developed for fabricating tandem white organic light-emitting diodes (WOLEDs). An investigation of the charge generation and separation process in Bphen:Li/Al/F-4-TCNQ/HAT-CN, which is carried out by analysis of the current-voltage and capacitance-voltage characteristics, shows that the proposed IC structure is suitable as a connecting unit in tandem OLEDs. The tandem WOLED based on a silicon compound host material of 10-phenyl-2'-(triphenylsilyl)-10H-spiro [acridine-9,9'-fluorene] (SSTF) with the proposed IC structure exhibits a maximum current efficiency of 159.2 cd A(-1) and a maximum power efficiency of 69.4 lm W-1. For application in large-area OLEDs, a 150 x 150 mm(2) tandem lighting panel with maximum efficiencies of 231.8 cd A(-1) and 52.9 lm W-1, correlated color temperature of 3000 K and Commission International de I'Eclairage (CIE) coordinates of (0.34, 0.45) is also demonstrated.