Article1: Light-emitting diodes- Bright and stable
Article2: Atomic Layer Deposition Chemistry: Recent Developments and Future Challenges**
1. External quantum efficiency.
The external quantum efficiency (EQE) for a light emitting diode (LED) is given by
ηext = αγELΦ, where:
γEL is the injection efficiency (number of excitons generated / number of electrons passing
through the device).
α is the extraction efficiency (number of photons emitted / number of photons generated in the device).
Φ is the quantum yield.
Read the article: U. Banin, Nat. Photonics, 2008, 2, 209.
(a) Which of the three variables above currently limits the EQE of quantum dot-based LEDs to about 1%?
(b) Why are all-inorganic devices desirable rather than hybrid organic-inorganic devices?
(c) List two challenges for charge injection in quantum dot LEDs.
2. Atomic layer deposition (ALD).
Read the article: M. Leskelä, M. Ritala, Angew. Chem. Int. Ed., 2003, 42, 5548.
(a) What is the advantage of the self-limiting mechanism of thin film growth by ALD?
(b) List five thin film compositions that can be deposited by ALD.
(c) Briefly describe an application of ALD.
3. Article summary.
The details for the term paper will be announced soon. There will be considerable latitude in your choice of the topic. Choose an article related to a topic of interest to you potentially for your term paper. You can perform a literature search, or you may choose articles from the lecture notes or text books. (The only articles off limits are those that have already been assigned or used in previous homework assignments.)
Hint: It is OK to use a communication/letter or short article. If you find a good, clearly written article, reading and critiquing it is straightforward.
(a) Attach a printed copy of the article.
(b) Describe the motivation for the research. (~100 words or less)
(c) Describe the major findings. (~150 words or less)
(d) What is a criticism that you have of this article? If you have no criticism, then suggest a future study that builds on this paper.