Light-Emitting Device HOMO Alignment for Lower Driving Voltage
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Solution Overview
Problem
Existing light-emitting devices face challenges with high driving voltage, high power consumption, low emission efficiency, and reliability issues, along with imbalanced carrier transport.
Innovation Solution
Incorporating a first organic compound with a specific HOMO level of -5.40 eV or lower, and a host material with a HOMO level difference of 0.60 eV or less, in the light-emitting layer structure, along with hole-transport materials in the hole-injection and hole-transport layers, to facilitate smooth carrier transport and reduce driving voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional organic EL devices are used, then light emission can be obtained, but high driving voltage and high power consumption occur
Solution Approach 1:
The patent applies parameter changes by optimizing the HOMO levels of organic compounds in different layers. Specifically, the hole-transport layer uses a compound with HOMO level of -5.40 eV or lower, and the light-emitting layer uses a compound with HOMO level within -5.00 eV to -6.00 eV, creating optimal energy level alignment that reduces driving voltage and power consumption.
Solution Approach 2:
The patent employs composite materials by combining specific organic compounds with defined HOMO levels in a multi-layer structure. The hole-injection layer, hole-transport layer, and light-emitting layer each use compounds with specifically controlled HOMO levels to achieve synergistic effects that lower overall device power consumption and driving voltage.
2Productivity
If conventional light-emitting devices are used, then light emission is achieved, but emission efficiency is low
Solution Approach 1:
The patent improves emission efficiency by changing the energy level parameters of the organic compounds. The light-emitting layer uses a compound with HOMO level specifically controlled within -5.00 eV to -6.00 eV, which optimizes hole injection and carrier recombination processes, thereby increasing light emission efficiency and reducing energy loss.
3Reliability
If conventional organic EL devices are used, then device operation is achieved, but reliability is poor
Solution Approach 1:
The patent enhances device reliability by changing the HOMO level parameter of the organic compounds to be within specific ranges. The hole-transport layer uses a compound with HOMO level of -5.40 eV or lower, which improves material stability and device longevity while maintaining operational performance.
4Ease of operation
If conventional light-emitting devices are used, then basic light emission function is achieved, but carrier balance is unfavorable
Solution Approach 1:
The patent applies local quality by assigning different HOMO level characteristics to different layers: the hole-injection layer uses a compound with HOMO level of -5.60 eV or lower, the hole-transport layer uses a compound with HOMO level of -5.40 eV or lower, and the light-emitting layer uses a compound with HOMO level within -5.00 eV to -6.00 eV. This localized optimization of energy levels achieves favorable carrier balance and improved energy efficiency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution results in a light-emitting device with low driving voltage, low power consumption, high emission efficiency, and improved reliability, along with favorable carrier balance.
Implementation Method 1
research and development have been extensively conducted on light-emitting devices (also referred to as light-emitting elements) utilizing electroluminescence (EL)
Implementation Method 2
light emission from the singlet excited state (S*) is referred to as fluorescence
Implementation Method 3
light emission from the triplet excited state (T*) is referred to as phosphorescence
Data Source
AI summary
The driving voltage of a light-emitting device is lowered to improve the emission efficiency. The light-emitting device includes a first electrode, a second electrode, a light-emitting layer, and a first layer. The light-emitting layer is positioned between the first electrode and the second electrode. The first layer is positioned between the first electrode and the light-emitting layer. The light-emitting layer contains a light-emitting substance. The first layer contains a first organic compound. The HOMO level of the first organic compound is lower than or equal to −5.40 eV. The first organic compound provides a light-emitting device represented by General Formula (G1) below (Note that Q is O or S in General Formula (G1). One of A and B represents a group represented by General Formula (g1) above, and the other of A and B and R1 to R31 each independently represent any of H, D, an alkyl group, a cyclic saturated hydrocarbon group, an alkoxy group, a cyano group, halogen, a haloalkyl group, and an aromatic hydrocarbon group. Note that R9 and R10 may be bonded to each other to form a spirocyclic structure).