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--- screen_manufacturing [2026/04/15 17:14] – [5. EML (emission layer) fabrication] sophie
+++ screen_manufacturing [2026/04/16 15:06] (current) – [5. EML (emission layer) fabrication] sophie
@@ Line 27: / Line 27: @@
 ##### deposition of organic emissive materials
-There are different deposition methods depending on the organic emissive materials selected for the OLED.
+There are different deposition methods depending on the size of the display.
-  * **vacuum thermal evaporation combined with an FMM** (Fine Metal Mask) - **for small sized displays**: This method is not selective, meaning the material is deposited everywhere in the equipment chamber : a FMM (Fine Metal Mask) is placed on top of the substrate to hide areas where no material should be deposited. The emissive layer of small display OLEDs consist of 3 emissive materials (respectively emitting red, blue and green light) that are placed side by side. Hence, there are actually 3 deposition steps using 3 different FMMs, one for each emissive material.
-  * **For larger sized display**, the use of an FMM is not appropriate due to a loss of resolution when the substrate size is increased.
+  * **vacuum thermal evaporation combined with an FMM** (Fine Metal Mask)(([[https://advanced.onlinelibrary.wiley.com/doi/epdf/10.1002/aelm.202500555|Vacuum Thermal Evaporation for OLEDs: Fundamentals, Optimization, and Implications for Perovskite LEDs]], C. Shen, Y. Hu, S. Zhou, et al., 2025)) - _for small sized displays_ : This method is not selective, meaning the material is deposited everywhere in the equipment chamber : an FMM (Fine Metal Mask) is placed on top of the substrate to hide areas where no material should be deposited. The space between the FMM and the substrate should not be to big to avoid a color mixed pattern. The emissive layer of small display OLEDs consists of 3 emissive materials (respectively emitting red, blue and green light) that are placed side by side. Hence, there are actually 3 successive deposition steps, one for each emissive material as illustrated in the image bellow. The emissive materials are usually organometallic (e.g.: Alq3 for green and blue phosphorescent light (([[https://www.sciencedirect.com/science/article/abs/pii/S0022309310002620|Photoluminescence characteristics of green and blue emitting Alq3 organic molecules in crystals and thin films]], Taiju Tsuboi, Yasuko Torii, 2010)), Ir(ppy)3 for phosphorescent green).
+{{ :capture_d_ecran_2026-04-15_175209.png?direct&400 |}}
+  * **vacuum thermal evaporation with open mask** - _for larger sized display_: the use of an FMM is not appropriate due to a loss of resolution when the substrate size is increased.
+{{ :capture_d_ecran_2026-04-15_175500.png?direct&400 |}}
 ### 6. ETL (electron transport fabrication)
 ### 7. cathode fabrication
 ### 8. encapsulation
+OLED devices are highly sensitive to moisture and oxygen. They require a water vapour transmission rate (WVTR) of less than 10<sup>–6</sup> g/m²/day. For this reason, the encapsulation process is crucial for maintaining a long lifetime. There are multiple encapsulation technologies:
+{{ ::classification_of_encapsulation_technologies.png?400 |}}
+The use of these technologies depends on multiple parameters of the screen.
+####Frit-seal
+{{ :frit-sealed_structure.png?400 |}}
+{{ ::frit-seal_process.png?400 |}}
+This method can't be used for large or flexible screens.
+####Face-seal
+{{ ::face-seal_structure.png?400 |}}
+{{ ::face-seal_process.png?400 |}}
+This method is used for large rigid screens.
+####Thin-Film Encapsulation
+{{ ::tfe_process.png?400 |}}
+{{ ::tfe_structure.png?400 |}}
+This method can be used for flexible screens.
+Sources : ([https://www.wiley.com/en-es/Flat+Panel+Display+Manufacturing-p-9781119161363|Flat Panel Display Manufacturing])
 ### 9. assembly
 ### 10. testings