Solvent-Free Optical Upconversion Organic Film Production
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Solution Overview
Problem
Existing methods for producing optical upconversion organic films using organic solvents have environmental concerns and result in low upconversion efficiency, and there is a need for films that can efficiently convert visible light into ultraviolet light at sunlight intensity or lower.
Innovation Solution
A production method involving temperature control and pressure application on a powder precursor containing a triplet sensitizer and organic luminescent material, with a temperature gradient and decompression to form a high-quality optical upconversion organic film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If organic solvents are used to dissolve and mix sensitizer and luminescent molecules, then the production process is simple, but environmental impact increases and upconversion efficiency decreases
Solution Approach 1:
The invention extracts and removes the organic solvent from the production process. Instead of dissolving sensitizer and luminescent molecules in organic solvent and then evaporating it, the patent directly processes the solid powder mixture through melting and cooling, eliminating the harmful solvent extraction and evaporation steps entirely.
Solution Approach 2:
The invention changes the physical state parameters of the materials. By heating the powder mixture to melt the luminescent molecules and then controlling the cooling rate, the patent transforms the production process from solution-based to melt-based, achieving both environmental friendliness and high upconversion efficiency.
2Productivity
If the mixture is heated and rapidly cooled to produce amorphous glass, then production is fast, but upconversion efficiency becomes low
Solution Approach 1:
The invention introduces dynamic control of the cooling process. Instead of uniform rapid cooling that produces amorphous glass, the patent applies different cooling rates to different regions of the sample, creating a temperature gradient that promotes crystal formation in regions where it enhances upconversion efficiency while maintaining overall production efficiency.
Solution Approach 2:
The invention creates local quality differences within the material. By establishing temperature gradients during cooling, different regions of the luminescent material develop different crystalline structures - some amorphous and some crystalline - with each region optimized for specific properties, thereby achieving high overall upconversion efficiency.
3Device complexity
If uniform temperature heating is applied, then the process is simple, but crystal orientation and upconversion efficiency are insufficient
Solution Approach 1:
The invention segments the temperature control into multiple zones. By dividing the heating/cooling system into regions with different temperature settings, the patent creates controlled temperature gradients that guide crystal growth in specific orientations, achieving high manufacturing precision without excessive overall system complexity.
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 method produces high-quality optical upconversion films with stable light conversion from visible to ultraviolet regions at excitation intensities lower than sunlight, achieving high upconversion quantum efficiency.
Implementation Method 1
a first temperature that is a temperature of a first end of the powder precursor and a second temperature that is a temperature of a second end of the powder precursor are raised by heating to or above a melting point of the organic luminescent material
Implementation Method 2
the crystal of the organic luminescent material has uniaxial orientation
Implementation Method 3
the lowest singlet state is generated by triplet-triplet annihilation (TTA) between the luminous molecules (DPA) that have been excited to the lowest triplet state by energy transfer from the sensitizer, and light emission occurs
Implementation Method 4
energy transfer from the sensitizer
Implementation Method 5
a heating member having a temperature gradient from a high temperature range to a low temperature range along the axial direction
Data Source
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AI summary
The following steps are performed: a precursor holding step (S1) of holding a powder precursor containing a triplet sensitizer and an organic luminescent material in a holding space having a predetermined height of a precursor holder; a pressing step (S2) of applying pressure to the powder precursor along a Z direction; and a temperature control step where a first temperature being a temperature of a first end of the powder precursor and a second temperature being a temperature of a second end thereof are raised by heating to or above a melting point of the organic luminescent material, and then are gradually lowered to below a coagulation point of the organic luminescent material while maintaining a temperature difference between the first and second temperatures, given that a -X-side end and a +X-side end of the powder precursor are defined as the first end and the second end, respectively.