Organic Semiconductor (EE430.859) 2014. 4. 29
Name	Department

* Write the answer in either Korean or English.

1. (20 point) Calculate the electronic energy structure of an ethylene molecule (C2H4) using Hückel theory. And draw molecular orbitals of each levels. Assume that the molecular orbitals of the ethylene molecule consist of the linear combination of atomic orbitals and the interaction integrals are as below:

2. (10 point)

(1) Explain the polaron effect in the organic semiconductor and draw the polaron levels in the energy diagram.

(2) Explain the difference between the energy gap measured by electrochemical methods and optical methods.

3.  (15 point) Explain the Franck-Condon effect in the optical absorption or emission spectrum.

4. (15 point) Explain the delayed fluorescence from the triplet state and calculate the decay time of the delayed fluorescence in terms of the triplet exciton lifetime τT.

5. (20 point) Explain the following method to get information on the internal electric field of organic devices.

(1) Electroabsorption measurement

(2) Photovoltaic measurement

6. (20 point) Explain the following models for the carrier mobility of organic semiconductors

(1) Poole-Frenkel model

(2) Bassler’s Gaussian Disorder Model