Mixed Powder for OLED Deposition with Controlled Vaporization
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Solution Overview
Problem
The premix technique for forming organic electroluminescence devices faces challenges in maintaining consistent mixing proportions of host and dopant compounds over long deposition periods, leading to variability in film quality and reduced yield due to differences in evaporation rates.
Innovation Solution
A mixed powder comprising specific organic compounds with controlled molar concentrations and vapor pressures is used, where the temperature difference between the compounds is maintained within a specific range to ensure stable vaporization ratios, thereby stabilizing the component proportions in the deposited film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a premix technique is used to simplify the deposition process, then device complexity is reduced, but manufacturing precision deteriorates due to variable mixing proportions in deposited films
Solution Approach 1:
The patent applies parameter changes by controlling the vapor pressure ratio of compounds in the mixed powder within a specific range (0.1 to 10) to maintain stable mixing proportions during continuous deposition. This parameter control ensures that even when one compound is present in small amounts, the vaporization rates remain balanced throughout the deposition process, resolving the precision issue while keeping the process simple
2Ease of manufacture
If compounds with different vaporization rates are used in premix, then ease of manufacture is improved, but reliability deteriorates due to variable component proportions over time
Solution Approach 1:
The patent transforms the approach by not using compounds with vastly different vaporization rates, but instead selecting compounds whose vapor pressure ratio falls within the controlled range of 0.1 to 10. This parameter optimization allows the deposition process to maintain reliable and consistent component proportions throughout continuous operation, even when depositing multiple substrates over extended periods
3Productivity
If a single deposition source is used for premix, then productivity is improved, but manufacturing precision worsens due to difficulty in controlling mixing proportions
Solution Approach 1:
The patent resolves this contradiction by optimizing the vapor pressure ratio parameter of the mixed powder compounds. By ensuring the vapor pressure ratio is between 0.1 and 10, the single deposition source can efficiently deposit multiple substrates while maintaining precise and consistent film composition throughout the process, eliminating the need for multiple deposition sources
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 ensures consistent component proportions in the film over extended deposition times, minimizing defective products and raw material loss, and improving the yield and productivity of organic electroluminescence devices.
Implementation Method 1
a first organic compound and a second organic compound... being solid at ordinary temperatures and pressures... the temperature T1 and the temperature T2 satisfy the following formula (2)
Implementation Method 2
the mixing proportion of the raw material mixture is reflected in the deposited film
Implementation Method 3
a vacuum deposition method is generally used
Data Source
AI summary
A mixed powder for an organic electroluminescence device, including a first organic compound and a second organic compound, and being solid at ordinary temperatures and pressures, wherein the organic electroluminescence device includes a cathode, an anode, and an emitting layer arranged between the cathode and the anode, and the emitting layer includes a compound C2 having delayed fluorescence, and each of the first organic compound and the second organic compound is a compound selected from the group consisting of a fluorescent emitting compound C1, the compound C2, and a compound C3 different from both the compound C1 and the compound C2, and they have the specific combination, wherein when MOL1 [mol %] is used as the molar concentration of the first organic compound in the mixed powder and MOL2 [mol %] is used as the molar concentration of the second organic compound in the mixed powder, MOL1 [mol %] and MOL2 [mol %] satisfy the following formula (1), wherein when M1 [kg/mol] is used as the molecular weight of the first organic compound, when P1 [Pa] is used as the vapor pressure obtained by ThermoGravimetry-Differential Thermal Analysis of the first organic compound at arbitrary temperature, when M2 [kg/mol] is used as the molecular weight of the second organic compound, and when P2 [Pa] is used as the vapor pressure obtained by ThermoGravimetry-Differential Thermal Analysis of the second organic compound at arbitrary temperature, the temperature T1 [° C.] of the first organic compound in the case of P1/M11/2=0.04×{MOL1/(MOL1+MOL2)} and the temperature T2 [° C.] of the second organic compound in the case of P2/M21/2=0.04×{MOL2/(MOL1+MOL2)} satisfy the following formula (2):0<MOL2/(MOL1+MOL2)≦0.45(1)-20° C.≦T1-T2≦40° C..(2)