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chemgirl83
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I would really appreciate if anyone can help me with these 2 questions! I really need help with my homework assignment and I don't have a good materials background...
1. Au has been found to be a very good anode electrode for OLEDs (see, for example, M.G.
Helander, et al. Adv. Mater. 22, 2037 (2010)). The problem of using a single layer Au
anode is its poor adhesion to glass substrates. Propose a method to improve the adhesion
at the Au/glass interface.
The proposed solution has the following constraints:
A) Optical transmission through the system (air/Au (x nm)/ material-X (y
nm)/glass substrate (1mm)/air) at 500 nm has to be > 40%. (You may use
bulk material optical constants in your calculation).
B) Electrical sheet resistance of your proposed thin-film structures has to be as
low as possible (no worse than that of ITO’s, 10 Ω/□).
and
2. PVD is now widely used to fabricate small molecular optoelectronic devices such as
OLED and solar cells. For OLED fabrication, deposition process of Al cathode has been
found critical in producing good working device. For example, the device efficiency of
OLED at 2.0 A/s Al deposition rate was found twice higher than that of OLED at 0.2 A/s
deposition rate (see the following figure). The working pressure during Al deposition was
8x10-6 torr. As the device fabrication conditions for other organic layers were kept the
same, the device performance disparity is related to the difference in the Al thin-film
properties including: (1) electrical, (2) optical, (3) chemical composition, and (4)
microstructural properties.
(a) Provide a theoretical hypothesis on the difference in these film properties
deposited by different deposition rates.
(b) Propose appropriate experimental techniques to verify your hypothesis.
1. Au has been found to be a very good anode electrode for OLEDs (see, for example, M.G.
Helander, et al. Adv. Mater. 22, 2037 (2010)). The problem of using a single layer Au
anode is its poor adhesion to glass substrates. Propose a method to improve the adhesion
at the Au/glass interface.
The proposed solution has the following constraints:
A) Optical transmission through the system (air/Au (x nm)/ material-X (y
nm)/glass substrate (1mm)/air) at 500 nm has to be > 40%. (You may use
bulk material optical constants in your calculation).
B) Electrical sheet resistance of your proposed thin-film structures has to be as
low as possible (no worse than that of ITO’s, 10 Ω/□).
and
2. PVD is now widely used to fabricate small molecular optoelectronic devices such as
OLED and solar cells. For OLED fabrication, deposition process of Al cathode has been
found critical in producing good working device. For example, the device efficiency of
OLED at 2.0 A/s Al deposition rate was found twice higher than that of OLED at 0.2 A/s
deposition rate (see the following figure). The working pressure during Al deposition was
8x10-6 torr. As the device fabrication conditions for other organic layers were kept the
same, the device performance disparity is related to the difference in the Al thin-film
properties including: (1) electrical, (2) optical, (3) chemical composition, and (4)
microstructural properties.
(a) Provide a theoretical hypothesis on the difference in these film properties
deposited by different deposition rates.
(b) Propose appropriate experimental techniques to verify your hypothesis.