A single component white electroluminescent device fabricated from a metallo-organic terbium complex

Abstract

Two new mixed ligand complexes [Eu(tfac)₃(DPEPO)] (Eu-1) and [Tb(tfac)₃(DPEPO)] (Tb-2) incorporating trifluoroacetylacetone (Htfac) and bis(2-(diphenylphosphino)phenyl)ether oxide (DPEPO) were synthesized in gram-scale quantities and used as emitters to fabricate single- and double-EML (light-emitting layer) electroluminescence (EL) devices. The single-EML device with the structure: ITO/HAT-CN (6 nm)/HAT-CN (0.2 wt%):TAPC (50 nm)/Eu-1 (1–6 wt%): 26DCzPPy (10 nm)/Tm3PyP26PyB (50 nm)/LiF (1 nm)/Al (100 nm) showed light red (CIE, x: 0.574; y: 0.275) emission for the Eu-1 based EL devices due to the presence of a host emission with a brightness of 1274 cd m⁻², current efficiency (η_c), power efficiency (η_p) and external quantum efficiency (EQE) of 0.58 cd A⁻¹, 0.68 lm W⁻¹, and 0.70%, respectively. The single-EML device for the Tb-2 complex with the same device structure displayed white-light emission. The optimized single-EML device of Tb-2 with 14.0 wt% doping concentration showed an impressive EL performance with brightness of 1637 cd m⁻², η_c ≈ 3.05 cd A⁻¹, η_p ≈ 2.80 lm W⁻¹, EQE ≈ 1.4%, V_turn-on ≈ 3.1 V, respectively. This is the first report of single component white organic light emitting diode (W-OLED) fabricated from an organo-Tb(III) complex. The W-OLEDs show low turn-on voltages (V_turn-on) ≈ 3.1 V and are thus advantageous in lowering the power consumption of the OLED display.