Organic Light Emitting Element With Exciplex Host System
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Solution Overview
Problem
Current organic light emitting devices face inefficiencies in light emission due to high driving voltage, which limits their performance in display and lighting applications.
Innovation Solution
Incorporating a light emitting layer with a host comprising both P-type and N-type hosts that produce an exciplex, along with a phosphorescent dopant, to achieve enhanced light emission efficiency and reduced roll-off phenomena.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional organic light emitting device uses a single-type host material in the light emitting layer, then the device structure is simple, but the light emitting efficiency is low and roll-off phenomenon occurs
Solution Approach 1:
The patent applies composite materials by combining P-type host and N-type host materials in the light emitting layer to form an exciplex system. This composite approach enables efficient energy transfer from the host mixture to the phosphorescent dopant, achieving high light emitting efficiency while maintaining device performance stability across different driving conditions.
Solution Approach 2:
The patent changes the chemical and electronic parameters of the host system by selecting specific P-type and N-type hosts with complementary properties. The P-type host (e.g., TCTA, TAPC) and N-type host (e.g., Alq3, BCP) are chosen to create an exciplex with appropriate energy levels, HOMO-LUMO offsets, and photoluminescence characteristics that optimize energy transfer to the phosphorescent dopant.
2Illumination intensity
If the driving voltage is high in an organic light emitting device, then the device can achieve sufficient light emission, but the power consumption increases and efficiency decreases
Solution Approach 1:
The patent optimizes the energy level parameters of the host and dopant materials to achieve efficient energy transfer at lower driving voltages. By carefully selecting P-type and N-type hosts with appropriate HOMO and LUMO levels, and matching them with phosphorescent dopants having suitable energy gaps, the device achieves high light emission intensity with reduced power consumption.
Solution Approach 2:
The exciplex formed by the P-type and N-type host mixture acts as an intermediary energy transfer mediator. This exciplex state facilitates efficient energy transfer to the phosphorescent dopant, enabling the device to achieve high illumination intensity at lower driving voltages and thus reducing overall power consumption.
3Productivity
If a phosphorescent dopant is used with P-type and N-type hosts forming an exciplex, then the light emitting efficiency is improved, but the device complexity increases
Solution Approach 1:
The patent employs composite materials in the light emitting layer by mixing P-type host, N-type host, and phosphorescent dopant. This composite system creates an exciplex that enables efficient energy transfer, achieving high light emitting efficiency. The complexity is managed by optimizing the weight ratios and ensuring proper energy level alignment among the components.
Solution Approach 2:
The patent applies local quality by assigning specific functional roles to each component in the light emitting layer: the P-type host provides hole transport and contributes to exciplex formation, the N-type host provides electron transport and contributes to exciplex formation, and the phosphorescent dopant is responsible for light emission. This functional differentiation optimizes overall device performance.
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 use of P-type and N-type hosts in the light emitting layer results in improved light emitting efficiency and stability, with a lower photon energy exciplex facilitating efficient energy transfer and reduced power consumption, thereby enhancing the overall performance of the organic light emitting device.
Implementation Method 1
a host including a P-type host and an N-type host, which produce an exciplex
Implementation Method 2
the host including the P-type host and the N-type host, which produce an exciplex, emits a photoluminescence light with a longer wavelength than a wavelength of each of the P-type host and the N-type host
Implementation Method 3
a phosphorescent dopant
Implementation Method 4
The principle of the organic light emission phenomenon is as follows. When an organic material layer is disposed between a anode and a cathode, if voltage is applied between internal parts of a specific organic molecule through the two electrodes, electrons and holes are injected into the organic material layer from the cathode and the anode, respectively. The electrons and the holes which are injected into the organic material layer are recombined to form an exciton, and the exciton falls down again to the ground state to emit light.
Data Source
AI summary
The present specification relates to an organic light emitting element comprising: an anode; a cathode disposed opposite to the anode; and a light emitting layer disposed between the anode and the cathode, wherein the light emitting layer comprises: a host including a P-type host and an N-type host for generating an exciplex; and a phosphorescent dopant, and the host including the P-type host and the N-type host for generating an exciplex emits photoluminescence light having a longer wavelength than that emitted from each of the P-type host and the N-type host.