Organic materials for an evaporation source
View Patent ↗A method of using a compacted pellet having uniform blended mixture with at least first and second different organic components that sublime at temperatures T 1 and T 2 respectively, wherein T 1 represents the temperature of the first organic material with the lowest sublimation temperature and T 2 represents the temperature of the second organic material with the highest sublimation temperature, to form an organic layer having a uniform blended mixture of the organic components, includes providing a compacted pellet, having a top and bottom surface, into a boat having an open top surface wherein the compacted pellet conforms to the interior of the boat; and applying heat to the top of the compacted pellet to cause the deposition of a uniform blended mixture of the organic components to form an organic layer.
1. A method of using a compacted pellet having uniform blended mixture with at least first and second different organic components that sublime at temperatures T 1 and T 2 respectively, wherein T 1 represents the temperature of the first organic material with the lowest sublimation temperature and T 2 represents the temperature of the second organic material with the highest sublimation temperature, to form an organic layer having a uniform blended mixture of the organic components, comprising:
(a) providing a compacted pellet, having a top and bottom surface, into a boat having an open top surface wherein the compacted pellet conforms to the interior of the boat; and
(b) applying heat to the top of the compacted pellet to cause the deposition of a uniform blended mixture of the organic components to form an organic layer, wherein the top surface of the compacted pellet reaches T 2 before the bottom surface reaches T 1 .
2. The method of claim 1 wherein during deposition, the value of M in the following relationship is less than 2:
M
=
(
(
T
2
-
T
0
)
2
-
(
T
1
-
T
0
)
2
)
K
ρ
C
p
D
F
2
B
2
wherein
ρ is the density of the compacted pellet (g/cc)
C p is the heat capacity of the compacted pellet (J/(g K))
T 0 is the initial temperature of the compacted pellet (C)
T 1 is the sublimation temperature of first organic material (C)
T 2 is the sublimation temperature of second organic material (C)
K is the thermal conductivity of the compacted pellet (W/(cm K))
D is the diffusion coefficient of vaporized first organic material (cm 2 /s)
F is the applied heat flux (W/cm 2 )
B is the vertical height of the compacted pellet (cm).
3. The method of claim 1 wherein the organic layer is part of an OLED structure.
4. A method of using a compacted pellet having uniform blended mixture with at least first and second different organic components that sublime at temperatures T 1 and T 2 respectively, wherein T 1 represents the temperature of the first organic material with the lowest sublimation temperature and T 2 represents the temperature of the second organic material with the highest sublimation temperature, to form an organic layer having a uniform blended mixture of the organic components, comprising:
(a) providing a compacted pellet, having a top and bottom surface, into a boat having an open top surface wherein the compacted pellet conforms to the interior of the boat; and
(b) applying heat to the top of the compacted pellet to cause the deposition of a uniform blended mixture of the organic components to form an organic layer, wherein the bottom surface reaches T 1 before the top surface reaches T 2 .
5. The method of claim 4 wherein when the bottom surface of the compacted pellet reaches T 1 before the top surface reaches T 2 , and the following relationship defines the window of time in which all the components in the boat sublime together: (t 2 −t 3 )<B 2 /D, wherein
t 2 is the time that the surface temperature reaches temperature T 2 ,
t 3 is the time that the bottom surface reaches temperature T 1 ,
B is the vertical height of the compacted pellet, and
D is the material diffusivity of the vaporized organic material with the lowest sublimation temperature.