Light-emitting Element Phthalocyanine Relay Layer Driving Voltage
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Solution Overview
Problem
Light-emitting elements face challenges in reducing driving voltage while maintaining efficient electron injection and preventing the formation of pn junctions and depletion layers, which can lead to increased power consumption.
Innovation Solution
Incorporating a phthalocyanine-based material as an electron relay layer between an acceptor and donor substance layer, with specific metal or compound additives to facilitate electron transport and prevent interaction, thereby reducing the driving voltage and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a layer in which an organic compound having a hole-transport property is doped with a metal oxide (acceptor substance) is in contact with a layer in which an organic compound having an electron-transport property is doped with a metal having a low work function (donor substance), then optical adjustment of emission spectrum can be performed and electron injection is facilitated, but a pn junction is formed and a depletion layer is created, causing an increase in driving voltage
Solution Approach 1:
An undoped organic compound layer is introduced as an intermediary between the acceptor-doped layer and the donor-doped layer. This intermediary layer prevents direct contact between the acceptor and donor substances, thereby avoiding the formation of a pn junction and depletion layer, while still allowing the system to achieve optical adjustment and electron injection functions through the adjacent doped layers.
2Illumination intensity
If the thickness of the metal oxide-doped layer is adjusted to perform optical adjustment, then emission spectrum can be optimized, but the driving voltage increases due to the formation of pn junction and depletion layer
Solution Approach 1:
The undoped organic compound layer serves as a mediator that separates the acceptor-doped and donor-doped layers. This allows the thickness of the metal oxide-doped layer to be adjusted for optimal emission spectrum without the harmful effect of pn junction formation, as the intermediary layer prevents direct interaction between oppositely doped substances.
3Productivity
If a layer doped with acceptor substance is in contact with a layer doped with donor substance, then charge transport is enhanced, but the acceptor and donor substances interact and block each other's function, causing increased driving voltage
Solution Approach 1:
The undoped organic compound layer acts as a physical barrier that prevents direct interaction between acceptor and donor substances. This intermediary layer allows charge transport to occur through the adjacent doped layers without the substances blocking each other's functions through direct contact, thereby maintaining high charge transport efficiency without increasing driving voltage.
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 effectively suppresses the increase in driving voltage and power consumption by preventing the formation of pn junctions and depletion layers, enhancing electron injection efficiency and maintaining conductivity stability.
Implementation Method 1
the second layer is provided between the first layer and the third layer and in contact with the first layer and with the third layer, and includes a phthalocyanine-based material
Implementation Method 2
The organic compound having a hole-transport property is a donor substance and the metal oxide is an acceptor substance. The metal having a low work function is a donor substance and the organic compound having an electron-transport property is an acceptor substance. Therefore, the layer doped with the acceptor substance is in contact with the layer doped with the donor substance. When the layer doped with the acceptor substance is in contact with the layer doped with the donor substance, a pn junction is formed to form a depletion layer.
Implementation Method 3
Light emission mechanism of the EL element will be described. Upon applying voltage to the pair of electrodes, electrons injected from the cathode and holes injected from the anode are recombined in a light-emission center of the EL layer. As a result of the recombination, energy is released so that light is emitted.
Data Source
AI summary
A light-emitting element includes an EL layer between an anode and a cathode, and a first layer, a second layer, and a third layer between the cathode and the EL layer. The first layer provided between the cathode and the second layer is in contact with the cathode and the second layer, and includes a substance having a hole-transport property and an acceptor substance. The second layer provided between the first layer and the third layer is in contact with the first layer and the third layer, and includes a phthalocyanine-based material. The third layer provided between the second layer and the EL layer is in contact with the second layer and the EL layer, and includes an alkali metal, an alkaline-earth metal, a rare-earth metal, an alkali metal compound, an alkaline-earth metal compound, or a rare-earth metal compound.