MIXED POWDER FOR AN ORGANIC ELECTROLUMINESCENCE DEVICE AND METHOD FOR PRODUCING THE SAME, METHOD FOR FABRICATING ORGANIC ELECTROLUMINESCENCE DEVICE BY USING THE MIXED POWDER, METHOD FOR SELECTING COMPOUNDS IN THE MIXED POWDER, AND COMPOSITION FOR VACUUM DEPOSITION

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