Rare Earth Complex as Electron Trapper and Energy Transfer Ladder for Efficient Red Iridium Complex Based Electroluminescent Devices

Abstract

In this work, we experimentally demonstrated the new functions of trivalent rare earth complex in improving the electroluminescent (EL) performances of iridium complex by codoping trace Eu(TTA)3phen (TTA = thenoyltrifluoroacetone, phen = 1,10-phenanthroline) into a light-emitting layer based on PQ2Ir(dpm) (iridium(III)bis(2-phenylquinoly-N,C(2'))dipivaloylmethane). Compared with a reference device, the codoped devices displayed higher efficiencies, slower efficiency roll-off, higher brightness, and even better color purity. Experimental results demonstrated that Eu(TTA)3phen molecules function as electron trappers due to its low-lying energy levels, which are helpful in balancing holes and electrons and in broadening recombination zone. In addition, the matched triplet energy of Eu(TTA)3phen is instrumental in facilitating energy transfer from host to emitter. Finally, highly efficient red EL devices with the highest current efficiency, power efficiency and brightness up to 58.98 cd A(-1) (external quantum efficiency (EQE) of 21%), 61.73 lm W(-1) and 100870 cd m(-2), respectively, were obtained by appropriately decreasing the doping concentration of iridium complex. At certain brightness of 1000 cd m(-2), EL current efficiency up to 51.94 cd A(-1) (EQE = 18.5%) was retained. Our investigation extends the application of rare earth complexes in EL devices and provides a chance to improve the device performances.

Very bright and efficient ITO-free narrow-spectrum micro-cavity top-emitting organic light-emitting diodes with low operation voltage

“…This can be attributed to the narrower energy gaps of host DIC-TRZ (3.0 eV) and the emitter, as well as the high hole mobility of TAPC (1 Â 10 À2 cm 2 V À1 s À1 ) and high electron mobility of Tm3PyP26PyB (1 Â 10 À2 cm 2 V À1 s À1 ). 5,38 As listed in Table 1, the current efficiency and EQE reached the maximum values at a brightness of 1000 cd m À2 . The current efficiency and EQE decreased slightly with increasing brightness from 1000 to 5000 cd m À2 , indicating the extremely slow efficiency roll-off of these devices.…”

“…Organic light-emitting diodes (OLEDs) have attracted increasing attention due to their applications in full-color displays and solid-state lighting. [1][2][3][4][5][6][7][8][9][10][11][12][13] However, their key performance parameters, including efficiency and lifetime, still require to be enhanced to unlock the full potential of OLEDs. 14 ITO has been extensively adopted as a transparent conductive electrode in OLED devices; however, its high refractive index (n E 2) resulting in waveguide modes in the active layers of OLED structures is responsible for the poorer extraction of internally generated emissions.…”

Efficient White Polymer Light‐Emitting Diode (WPLED) Based on Single‐Component Eu3+–Tb3+‐Containing Metallopolymer

“…The device WPLDE-II with a configuration (Figure 6(a) applied as both hole-blocking and electron-transporting layer. The peculiar stepwise alignments [50] of both HOMO and LUMO levels from CBP:Poly(NVK-co-2-co-7) to TPBI and to BCP, promote transports of the injected holes and electrons. As a result, charge carriers are confined within the broaden This article is protected by copyright.…”

The application of rare earth complexes in organic electroluminescent devices

“…1998年, 黄春晖研究组 [29] Rino等 [33] Yu等 [36] 将Tb(PMIP) 3 用作发光材料, DCPPO和 图 2 (a) 优化Alq 3 蒸镀速率的电流密度-电压曲线, 插图为器件的电流效率-电流密度曲线; (b) 不同发光层厚度的电流密度-电 压曲线, 插图为器件的电流效率-电流密度曲线 [25] (网络版彩图) [38] (网络版 彩图)…”