Exciplex Light-Emitting Element Triplet Energy Harvesting

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Solution Overview

Problem

Conventional light-emitting elements face limitations in achieving high emission efficiency due to the statistical generation ratio of excited states, with only 25% of singlet excited states being utilized, leading to suboptimal performance.

Innovation Solution

A light-emitting element structure is developed where a first organic compound with electron-transport properties and a second organic compound form an exciplex, enhancing the generation probability of singlet excited states beyond theoretical values, allowing for increased luminescence from singlet excited states and efficient energy transfer from triplet excited states.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If conventional light-emitting elements use standard organic compounds without exciplex formation, then the structure is simple and ease of manufacture is maintained, but emission efficiency is limited to theoretical maximum of 25% from singlet excited states

Engineering Contradiction:

Improvestructural simplicityVSAvoidemission efficiency

Core Design Contradiction:

Ease of manufactureVSProductivity

Solution Approach 1:

The patent uses composite materials by forming an exciplex (excited complex) between a host compound and a guest compound in the light-emitting layer. This composite system enables energy transfer from triplet to singlet states, achieving emission efficiency exceeding the theoretical 25% limit while maintaining a relatively simple two-compound structure that is easier to manufacture than complex multi-layer systems.

Inventive Principle:

Principle #40Composite materials

2Device complexity

If conventional light-emitting elements rely on statistical generation of excited states, then device complexity is low, but emission efficiency cannot exceed theoretical limits

Engineering Contradiction:

Improveoperational simplicityVSAvoidemission efficiency

Core Design Contradiction:

Device complexityVSProductivity

Solution Approach 1:

The patent changes the energy state parameters by introducing a guest compound with appropriate energy levels into the light-emitting layer. This parameter modification enables triplet-to-singlet energy transfer, fundamentally altering the emission mechanism to exceed theoretical efficiency limits while maintaining operational simplicity through a single light-emitting layer design.

Inventive Principle:

Principle #35Parameter changes

3Ease of operation

If light-emitting elements utilize only singlet excited states for luminescence, then the mechanism is simple and ease of operation is maintained, but energy utilization is inefficient with 75% loss from triplet states

Engineering Contradiction:

Improvemechanism simplicityVSAvoidtriplet state energy loss

Core Design Contradiction:

Ease of operationVSLoss of energy

Solution Approach 1:

The patent converts the previously harmful or wasted triplet excited states into beneficial energy sources for light emission. By introducing the guest compound that accepts triplet energy and transfers it to singlet states, the system transforms the 75% energy loss from triplet states into useful luminescence, reducing energy waste while maintaining mechanism simplicity through a unified light-emitting layer.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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

This approach results in a light-emitting element with improved emission efficiency, exceeding theoretical limits by contributing triplet excited energy to light emission, thereby enhancing external quantum efficiency and reducing operational voltage.

Implementation Method 1

a first organic compound and a second organic compound form an exciplex (excited complex) in a light-emitting layer

Methodology Applied

Scientific EffectExciplex formation:

Implementation Method 2

part of energy in T1 of the exciplex easily transfers to S1 without thermal deactivation

Methodology Applied

Scientific EffectEnergy transfer:

Implementation Method 3

electrons injected from the cathode and holes injected from the anode are recombined in a light emission center of the EL layer to form molecular excitons, and energy is released and light is emitted

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Implementation Method 4

electrons injected from the cathode and holes injected from the anode are recombined in a light emission center of the EL layer to form molecular excitons

Methodology Applied

Scientific EffectElectron-hole recombination:

Implementation Method 5

Luminescence from the singlet excited state (S1) is referred to as fluorescence

Methodology Applied

Scientific EffectFluorescence: Fluorescence

Implementation Method 6

luminescence from the triplet excited state (T1) is referred to as phosphorescence

Methodology Applied

Scientific EffectPhosphorescence: Phosphorescence

Data Source

PatentUS20180309080A1Light-Emitting Element, Light-Emitting Device, Electronic Device, and Lighting Device

Publication Date: 2018.10.25 SEMICON ENERGY LAB CO LTD

AI summary

The light-emitting element has a structure in which a first organic compound and a second organic compound form an exciplex (excited complex) in a light-emitting layer. The S1 level and the T1 level of the formed exciplex are positioned extremely close to each other compared to the S1 level and the T1 level of the respective substances (the first organic compound and the second organic compound) before the formation of the exciplex.