BAlq, photochemically stable blue-emitting layer material in OLEDs

Used to improve the efficiency and lifetime of PHOLEDs

Bis(8-hydroxy-2-methylquinoline)-(4-phenylphenoxy)aluminum, known as BAlq or BAlq₃, is widely used as blue-emitting layer materials in organic light-emitting diodes. It is also used as hole-blocking layer or as a “barrier-softening” interfacial layer in between the electron transporting and emissive layers [1, 2, 3, 4].

BAlq is also applied as the host material and electron-transport type hole-blocking layer in red PHOLEDs, and to improve the efficiency and lifetime of PHOLEDs. As a hole-blocking material, it is known to allow for high lifetimes, up to 160,000 hours at a luminance level of 100 cd/m²[3].

BAlq has a glass transition temperature of 99 °C and is photochemically stable [5].

General Information

CAS number	146162-54-1
Chemical formula	C₃₂H₂₅AlN₂O₃
Molecular weight	512.53 g/mol
Absorption	λ_max 259 nm (in THF)
Fluorescence	λ_em 334,477 nm (in THF)
HOMO/LUMO	HOMO = 5.9 eV, LUMO = 2.9 eV
Synonyms	BAlq₃ Bis(8-hydroxy-2-methylquinoline)-(4-phenylphenoxy)aluminum Aluminum 4-biphenylolate 2-methyl-8-quinolinolate
Classification / Family	Electron transporting materials, Hole blocking materials, Light emitter layer materials, Phosphorescent host materials, Organic light-emitting diodes, Organic electronics, Sublimed materials

Product Details

Purity	>99% (sublimed)
Melting point	Melting point/range: 207 - 214 °C (lit.)
Colour	Light-yellow powder/crystals

*Sublimation is a technique used to obtain ultra pure-grade chemicals. For more details about sublimation, please refer to the .

Chemical Structure

Chemical Structure of Bis(8-hydroxy-2-methylquinoline)-(4-phenylphenoxy)aluminum (BAlq)

Device Structure(s)

Device structure	ITO (110 nm)/NPB(80 nm)/BtpIr-doped BAlq* (47.5 nm)/Alq₃(30 nm)/Li₂O(0.5nm)/Al(100nm) [5]
Colour	Red
Max. EQE	8.6%
Max. Luminance	179 cd/m²

Device structure	ITO/CuPc (15 nm)/NPB (80 nm)/NPB: 0.5 wt% DCJTB (20 nm) /Alq₃:0.5 wt% C545T (3 nm)/MADN:0.8 wt% DSA-ph(40 nm)/BAlq₃ (10 nm)*/LiF/Al [6]
Colour	White
Max. Luminance	45,000 cd/m²
Max. Current Efficiency	20.8 cd/A
Max. Power Efficiency	15.9 lm W⁻¹

Device structure	ITO/MoO_x (5 nm)/NPB (40 nm)/4% Y-Pt:TCTA (20 nm)/8% FIrpic:mCP(10 nm)/8% FIrpic:UGH2 (10 nm)/BAlq* (40 nm)/LiF (0.5 nm)/Al (100 nm) [7]
Colour	White
Max. EQE	16.0%
Max. Current Efficiency	45.6 cd/A
Max. Power Efficiency	35.8 lm W⁻¹

*For chemical structure informations please refer to the cited references

Characterisation (TGA and DSC)

TGA and DSC trace of Bis(8-hydroxy-2-methylquinoline)-(4-phenylphenoxy)aluminum (BAlq).

MSDS Documentation

Literature and Reviews

Electroluminescent properties of organic light-emitting diodes using BAlq and Alq3 co-evaporation layer, Y. Iwama et al., Thin Solid Films 499, 364-368 (2006).
Electroluminescent mechanism of organic light-emitting diodes with blue-emitting Alq, T. Itoh et al., Colloids and Surfaces A: Physicochem. Eng. Aspects 284–285, 594–598 (2006).
A host material containing tetraphenylsilane for phosphorescent OLEDs with high efficiency and operational stability, J-W. Kang et al., Org. Electronic, 9, 452–460 (2008).

Electron transport in the organic small-molecule material BAlq — the role of correlated disorder and traps, S.L.M. van Mensfoort et al., Org. Electronic, 11, 1408–1413 (2010).
Distinguished Paper: Red-Phosphorescent OLEDs Employing Bis(8-Quinolinolato)-Phenolato-Aluminum(III) Complexes as Emission-Layer Hosts, T. Tsuji et al., SID Symposium Digest of Technical Papers, 35 (1), 900-903 (2012).
High efficiency fluorescent white organic light-emitting diodes with red, green and blue separately monochromatic emission layers, Z. Zhang et al., Org. Electronics, 10, 491-495 (2009); doi:10.1016/j.orgel.2009.02.006.
High Efficiency White Organic Light-Emitting Devices Incorporating Yellow Phosphorescent Platinum(II) Complex and Composite Blue Host, S-L. Lai et al., Adv. Funct. Mater., 23, 5168–5176 (2013); DOI: 10.1002/adfm.201300281.