Solid Light Up-conversion Material Crystallization Control
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Solution Overview
Problem
Conventional organic light up-conversion materials face challenges in achieving high efficiency due to separate crystallization of sensitizer and luminescent substances during solidification, which inhibits energy transfer, and are also affected by oxygen, making it difficult to produce solid materials with high light up-conversion efficiency.
Innovation Solution
The approach involves rapidly crystallizing the luminescent substance before the sensitizer, adjusting their concentrations, and optimizing solvent evaporation conditions to create a solid light up-conversion material using a compound represented by a specific general formula, ensuring the sensitizer remains uncrystallized and is incorporated into the luminescent substance, thereby enhancing energy transfer and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional organic light up-conversion materials are solidified, then they become solid materials suitable for practical use, but separate crystallization of sensitizer and luminescent substances occurs which inhibits energy transfer and reduces light up-conversion efficiency
Solution Approach 1:
The patent segments the crystallization process by controlling the crystallization of the luminescent substance separately from the sensitizer. The luminescent substance crystallizes first to form a crystal lattice, while the sensitizer remains in the amorphous phase within the crystal, preventing separate crystallization and ensuring efficient energy transfer.
Solution Approach 2:
The patent applies preliminary action by pre-cooling the solution to a temperature below the crystallization point of the luminescent substance before adding the sensitizer. This ensures that when the solution is later warmed, the luminescent substance crystallizes first and incorporates the sensitizer, preventing subsequent separate crystallization.
2Reliability
If high concentration of luminescent substance is used to improve light up-conversion efficiency, then more luminescent molecules are available for energy transfer, but the material becomes difficult to handle and process
Solution Approach 1:
The patent changes the physical state parameter from liquid to solid by controlling crystallization. The solid crystalline form maintains high luminescent substance concentration for efficient energy transfer while providing mechanical stability and ease of handling that liquids lack.
3Stability of the object's composition
If conventional solid organic light up-conversion materials are produced, then they are suitable for practical applications, but they remain significantly affected by oxygen which reduces efficiency
Solution Approach 1:
The patent merges the sensitizer and luminescent substance into a single crystalline phase rather than having separate phases. The sensitizer molecules are incorporated within the luminescent substance crystal lattice, creating a unified structure that protects against oxygen interference and maintains 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
This method results in a solid organic light up-conversion material with significantly improved light up-conversion efficiency, exceeding 10% luminescence quantum yield, and is less affected by oxygen, overcoming previous limitations in solid material production.
Implementation Method 1
a photosensitizer molecule (1A) in its ground state absorbs light energy to transit to an excited singlet state (1A*) (1A+hv→1A*)
Implementation Method 2
intersystem crossing to an excited triplet state (3A*) rapidly occurs (1A*→3A*)
Implementation Method 3
energy is transferred from the photosensitizer molecule in the excited triplet state to a luminescent molecule. As a result, the photosensitizer molecule loses the energy to return into its ground state. On the other hand, a luminescent molecule (1E) in its ground state changes into an excited triplet (3E*) (triplet-triplet energy transfer: 3A*+1E→1A+3E*)
Implementation Method 4
When the concentration of luminescent molecules having changed into the excited triplet state increases, interaction between the luminescent molecules having changed into the excited triplet state occurs more efficiently, and energy transfers from the one luminescent molecule having changed into the excited triplet state to the other luminescent molecule. At this time, the one luminescent molecule having changed into the excited triplet state returns to the ground state, and the other changes into an excited singlet state (triplet-triplet annihilation process: 3E*+3E*→1E+1E*)
Implementation Method 5
Then, up-converted light (1E*→1E+hvf) is emitted as fluorescence from the luminescent molecule having changed into the excited singlet state
Implementation Method 6
a method of producing a light up-conversion material including the step of drying a solution containing a compound represented by general formula (1) and a photosensitizer
Data Source
AI summary
The present invention relates to an organic light up-conversion material in a solid state that realizes high light up-conversion efficiency.