Method for selecting material for organic light-emitting device

Patent metadata

Field	Value
Publication number	US-12517088-B2
Application number	US-202017442259-A
Country	US
Kind code	B2
Filing date	May 15, 2020
Priority date	May 15, 2019
Publication date	Jan 6, 2026
Grant date	Jan 6, 2026

Abstract

Provided is a method for selecting a material for an organic light-emitting device, the method including comparing the reversibilities (electrical stability in the (+) radical and (−) radical states of a material) of the material using cyclic voltammetry (CV).

First claim

The invention claimed is:

1 . A method for selecting a material for an organic light emitting device, the method comprising:
(S1) obtaining cyclic voltammograms of two or more samples, respectively within an oxidation range or reduction range at one to three scan rates using cyclic voltammetry (CV), wherein the scan rate is 1 to 3 of 10 mV/s, 50 mV/s, 100 mV/s, 300 mV/s, and 500 mV/s, respectively; (S2) comparing reversibilities of the samples by using the cyclic voltammogram and classifying the samples into <Group 1> or <Group 2>; and (S3) selecting a material for a light emitting layer, a hole transport layer, an electron blocking layer, an electron transport layer, or a hole blocking layer of an organic light emitting device based on the comparison of the reversibilities, wherein in the classifying of the sample of (S2), <Group 1> or <Group 2> are defined as follows: <Group 1> Samples (1) having forward and inverse peaks at all scan rates and no impurity peaks at all scan rates or (2) having forward and inverse peaks at all scan rates and impurity peaks at one or more scan rates; and <Group 2> Samples having no inverse peaks at one or more scan rates; wherein in the comparing of the reversibilities of the samples of (S2): the samples in <Group 1> are classified as more stable than those in <Group 2>, among samples having no impurity peak in <Group 1>, samples having high reversibility at the same scan rate are classified as stable, among samples having no impurity peak and samples having impurity peaks in <Group 1>, samples having high reversibility at the same scan rate are classified as stable, among samples having impurity peaks in <Group 1>, samples having high reversibility at the same scan rate or a smaller height (I i ) of the impurity peak than a height (I f ) of the forward peak are classified as stable, provided that when there is a sample having neither inverse peak nor forward peaks present at one or more scan rates, samples are compared at rates other than the rate at which neither inverse peaks nor forward peaks are present, and among samples belonging to <Group 2>, samples having the smaller maximum rate at which inverse peaks are not present are classified as stable, the reversibility is calculated by the following Equation 1:
Reversibility= I r /I f   <Equation 1>

wherein in Equation 1, I r means the height of the inverse peak, and I f means the height of the forward peak, wherein: a material having a highest occupied molecular orbital (HOMO) absolute value of 4.30 eV to 4.60 eV, and a reversibility value (Ir/If) of 0.83 or higher within an oxidation range at a scan rate of 100 mV/s at the time of measuring cyclic voltage current is suitable as a material for a hole transport layer; a material having a reversibility value (Ir/If) of more than 0.5 within an oxidation range at a scan rate of 100 mV/s at the time of measuring cyclic voltage current is suitable as a material for an electron blocking layer; a material having a lowest unoccupied molecular orbital (LUMO) absolute value of 2.40 eV to 2.74 eV, and a reversibility value (Ir/If) larger than [−23.14+8.458×(the LUMO absolute value)] within a reduction range at a scan rate of 100 mV/s at the time of measuring cyclic voltage current is suitable as a dopant material for a blue light emitting layer; a material having a LUMO absolute value of 2.60 eV to 2.90 eV, and a reversibility value (Ir/If) larger than [4.96-1.535×(the LUMO absolute value)] within a reduction range at a scan rate of 100 mV/s at the time of measuring cyclic voltage current can be used is suitable as a material for an electron transport layer; a material having both a forward peak and an inverse peak at a scan rate of 100 mV/s at the time of measuring cyclic voltage current within an oxidation range is suitable as a material for a hole blocking layer; a material having a reversibility value (Ir/If) of [1.34×(the dipole moment)−0.293] or higher within an oxidation range at a scan rate of 500 mV/s and a reversibility value (Ir/If) of 0.95 or higher within a reduction range at a scan rate of 10 mV/s, at the time of measuring cyclic voltage current is suitable as a host material for a blue light emitting layer; and a material having a reversibility value (Ir/If) of [0.955−0.1786×(a stability value (Ir/If) within an oxidation range)] or higher within a reduction range at a scan rate of 10 mV/s, at the time of measuring cyclic voltage current is suitable as a host material for a light emitting layer.

2 . The method of claim 1 , wherein in Step (S1), a cyclic voltammogram is obtained by dissolving the sample within the oxidation range or the reduction range in an organic solvent.

3 . The method of claim 2 , wherein the organic solvent is dimethylformamide (DMF).

Assignees

• Lg Chemical Ltd

Inventors

• Kim Jihye
• Hong Sung Kil
• Kim Yeon Hwan
• Kwon Daegyeon
• Ahn Heesung

Classifications

• B07C5/344

  according to electric or electromagnetic properties {(sorting according to size measured electrically or electronically B07C5/08; material testing by magnetic means G01N24/00, G01N27/00, by electrical means G01N27/00; electrical measuring devices in general G01R; coin testing G07D5/00)} · CPC title

• C07D209/86

  with only hydrogen atoms, hydrocarbon or substituted hydrocarbon radicals, directly attached to carbon atoms of the ring system · CPC title

• H10K71/00

  Manufacture or treatment specially adapted for the organic devices covered by this subclass · CPC title

• C07D403/14

  containing three or more hetero rings · CPC title

• C07D405/04

  directly linked by a ring-member-to-ring-member bond · CPC title