OLED Exciplex Emitters for Stable Green and Red Displays
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Solution Overview
Problem
There is a need for highly stable and efficient green and red emitters in organic light emitting diodes (OLEDs) to improve the performance and longevity of OLED displays.
Innovation Solution
The development of an OLED comprising a first and second complex that form exciplexes when a voltage is applied, emitting luminescent radiation, with the exciplexes formed within, between, or both within and between the complexes, enhancing the stability and efficiency of the device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If highly stable phosphorescent blue emitter is used, then device stability is improved, but material availability and efficiency are worsened due to difficulty in achieving stable phosphorescent blue emitters
Solution Approach 1:
The patent changes the emission mechanism from phosphorescent to exciplex-based fluorescent emission, altering the fundamental parameters of the emitter system. This enables the use of stable organic compounds that form exciplexes at the interface between electron-transporting and hole-transporting layers, achieving both stability and manufacturability
Solution Approach 2:
The invention employs composite material systems consisting of electron-transporting materials (ETM) and hole-transporting materials (HTM) that work together to form exciplexes. The emission properties arise from the interface between these two material classes, combining their respective advantages to achieve stable and efficient blue emission
2Device complexity
If conventional emitters are used in R/G layer, then device structure is simplified, but emission efficiency and stability are worsened
Solution Approach 1:
The patent changes the emission mechanism in the R/G layer from conventional fluorescent or phosphorescent emission to exciplex-based emission. This parameter change enables simultaneous achievement of high efficiency and stability while maintaining relatively simple device structure through the use of standard OLED layer architecture
3Ease of operation
If OLEDs operate at room temperature, then device operation is simplified, but luminescent efficiency is worsened due to thermal energy loss
Solution Approach 1:
The patent changes the energy transfer mechanism to exciplex formation, which has favorable energy level alignment that minimizes thermal energy loss. The exciplex emission occurs at energies below the triplet states of both ETM and HTM, enabling efficient energy utilization at room temperature without requiring cryogenic operation
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 highly efficient and stable OLED that achieves improved performance and longevity, particularly in large size displays, with the exciplex formation contributing to enhanced luminescent radiation and extended device lifespan.
Implementation Method 1
when a voltage is applied across the anode and cathode at room temperature, the OLED emits a luminescent radiation that comprises one or more luminescent radiation components resulting from the formation of at least one exciplex
Implementation Method 2
the exciplex is formed by at least one of the following aggregate types: 1) at least one aggregate within the first complex, and at least one aggregate within the second complex; 2) at least one aggregate between the first and the second complex
Data Source
AI summary
Organic light emitting devices (OLEDs) are described, the OLEDs comprising an anode; a cathode; and an organic region, disposed between the anode and the cathode, comprising a first complex and a second complex; wherein when a voltage is applied across the anode and cathode at room temperature, the OLED emits a luminescent radiation that comprises one or more luminescent radiation components resulting from the formation of at least one exciplex; wherein the exciplex is formed by at least one of the following aggregate types: 1) at least one aggregate within the first complex, and at least one aggregate within the second complex; 2) at least one aggregate between the first and the second complex; and 3) both 1 and 2.