8-Hydroxyquinolinolato-lithium (Liq), coupled with aluminum (Al), is commonly used as an electron injection layer (EIL) material in organic electronic devices, particularly OLEDs. Normally, only a very thin layer (1-2 nm) Liq is needed for efficient electron injection from the electrode to the electron transport layer (ETL).

Liq/Al has also been widely known to be an effective cathode system towards general electron transport layer materials. It has also been reported that ultrathin Liq interlayers can greatly enhance the operational stability of light-emitting diodes [2].

General Information

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CAS number	25387-93-3
Chemical formula	C9H6LiNO
Molecular weight	151.09 g/mol
Absorption	λmax 261 nm (in THF)
Fluorescence	λem 331 nm (in THF)
HOMO/LUMO	HOMO = 5.58 eV, LUMO = 3.15 eV [1]
Synonyms	Liq, Lithium-8-hydroxyquinolinolate, Lithium 8-quinolinolate, 8-Hydroxyquinolinolato lithium
Classification / Family	Electron transport layer (ETL) materials, Organic Light-Emitting Diodes, Organic electronics, Sublimed materials

Product Details

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Purity	>99% (sublimed), >98% (unsublimed)
Melting point	366-368 ºC (lit.)
TGA	Td ≥ 430 oC (5%)
DSC	Tm =365 oC (+/- 1oC)
Colour	Light yellow powder

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

Chemical Structure

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Chemical Structure of 8-Hydroxyquinolinolato-lithium (Liq)

Device Structure(s)

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Device structure	ITO (150 nm)/NPB (70 nm)/mCP:Firpic-8.0%:Ir(ppy)3-0.5%:Ir(piq)3-0.5% (30 nm)/TPBi (30 nm)/Liq (2 nm)/Al (120 nm) [3]
Colour	White
Max. Luminance	37,810 cd/m2
Max. Current Efficiency	48.1 cd/A

Device structure	ITO (180 nm)/TAPC (60 nm)/mCP:Firpic–8 wt% (10 nm)/Ir(ppz)3 (1.5 nm)/mCP:Firpic–8 wt% (10 nm)/Ir(ppz)3 (1.5 nm)/mCP:Firpic–8 wt% (10 nm)/TPBi (30 nm)/Liq (2 nm)/Al (120 nm) [4]
Colour	Blue
Luminance@200 cd/m2	32,570 cd/m2
Max. Current Efficiency	43.76 cd/A
Max. EQE	23.4%
Max. Power Efficiency	21.4 lm W−1

Device structure	Al/MoO3 (3 nm)/mCP (50 nm)/Ir(tfmppy)2(tpip)* (0.5 nm)/TPBi (2.5 nm)/mCP (2.5 nm)/Ir(tfmppy)2(tpip) (0.5 nm)/TPBi (10 nm)/Bphen (45 nm)/Liq (1 nm)/Al (1 nm)/Ag (22 nm)/mCP (80 nm) [5]
Colour	Green
Max. Current Efficiency	126.3 cd/A

Device structure	ITO/ NPB (70 nm)/DPVBi:BCzVBi (15 wt%, 15 nm)/ADN:BCzVBi (15% wt%, 15 nm)/BPhen (30 nm)/ Liq (2 nm)/Al (100 nm) [6]
Colour	Deep Blue
Max. Luminance	8,668 cd/m2
Max. Current Efficiency	5.16 cd/A

Device structure	ITO/NPB/DPVBi:BCzVBi-6%/MADN:DCM2-0.5%/Bphen/Liq/Al [7]
Colour	White
Max. Luminance	15,400 cd/m2
Max. Current Efficiency	6.19 cd/A

Device structure	ITO/PEDOT:PSS (40 nm)/ CzDMAC-DPS* (40 nm)/TPBI (40 nm)/Liq (1.6 nm)/Al (100 nm) [8]
Colour	Greenish-Blue
Max. Current Efficiency	30.6 cd/A
Max. Power Efficiency	12.2 lm W−1

Device structure	ITO/HTL (100 nm)/CBP:9 wt%DACT-II*(40 nm)/BAlq (30 nm)/Liq/Al [9]
Colour	Green
Max. EQE	41.3%

*For chemical structure information, please refer to the cited references.

Characterisation

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TGA and DSC trace of 8-Hydroxyquinolinolato-lithium (Liq).