Highly Efficient Red and White Organic Light-Emitting Diodes with External Quantum Efficiency beyond 20% by Employing Pyridylimidazole-Based Metallophosphors

Abstract

Two highly efficient red neutral iridium(III) complexes, Ir1 and Ir2, were rationally designed and synthesized by selecting two pyridylimidazole derivatives as the ancillary ligands. Both Ir1 and Ir2 show nearly the same photoluminescence emission with the maximum peak at 595 nm (shoulder band at about 638 nm) and achieve high solution quantum yields of up to 0.47 for Ir1 and 0.57 for Ir2. Employing Ir1 and Ir2 as emitters, the fabricated red organic light-emitting diodes (OLEDs) show outstanding performance with the maximum external quantum efficiency (EQE), current efficiency (CE), and power efficiency (PE) of 20.98%, 33.04 cd/A, and 33.08 lm/W for the Ir1-based device and 22.15%, 36.89 cd/A, and 35.85 lm/W for the Ir2-based device, respectively. Furthermore, using Ir2 as red emitter, a trichromatic hybrid white OLED, showing good warm white emission with low correlated color temperature of <2200 K under the voltage of 4-6 V, was fabricated successfully. The white device also realizes excellent device efficiencies with the maximum EQE, CE, and PE reaching 22.74%, 44.77 cd/A, and 46.89 lm/W, respectively. Such high electroluminescence performance for red and white OLEDs indicates that Ir1 and Ir2 as efficient red phosphors have great potential for future OLED displays and lightings applications.

Recent Progress on Circularly Polarized Luminescent Materials for Organic Optoelectronic Devices

“…complexes which can modulate the chiroptical properties (CD or CPL signals) by regulating the ligands and coordination modes. Furthermore, these phosphorescent emitters can capture both singlet and triplet excitons simultaneously, which makes them possible to improve the performance of optoelectronic devices …”

Designing Highly Efficient Phosphorescent Neutral Tetrahedral Manganese(II) Complexes for Organic Light‐Emitting Diodes

“…Phosphorescent transition‐metal complexes have played the vital role in the rapid development of OLEDs, because they can harvest both singlet and triplet excitons to achieve an internal quantum efficiency of 100% owing to the highly efficient spin‐orbit coupling effect induced by heavy‐metal atoms . For example, noble metal‐based phosphors including iridium(III) complexes, platinum(II) complexes, and gold(III) complexes have been widely used in phosphorescent OLEDs (PhOLEDs). However, these noble metals suffer from the low abundance and high cost.…”

Synthesis and properties of hyperbranched polymers for white polymer light-emitting diodes

“…In these devise, ITO and Al are used as anode and cathode, respectively; PEDOT:PSS and TPBi are used as hole transport layer and electron transport layer, respectively; 50 nmthick polymers layer is used as EML, and 1 nm-thick LiF layer used as electron injection layer. 1,[31][32][33][34][35] Fig . 6a-d shows the EL spectra for all polymers-based PLEDs at voltages varying from 7 to 11 V. It can be seen that all resulting PLEDs with PFCzSDF10Ir6, PFCzSDF10Ir7, PFCzSDF10Ir8, PFCzSDF10Ir9 as realize good white emission with CIE coordinate of at (0.27,0.25), (0.27,0.24), (0.26,0.30), and (0.27,0.31) at 11 V, respectively, and the EL spectra for these PLEDs all contain two main emission peaks located at blue and orange-red wavebands, which are corresponding to the emissions of poly(uorene-altcarbazole) branches and red dimming phosphor group (Ir(piq) 2acac).…”