M.Sc. (Semester III) (CBCS) Examination Nov/Dec-2018
Nano-Technology
ORGANIC SEMICONDUCTORS, POLYMERS MOLECUAR ELECTRONICS
Time: 2½ Hours Max. Marks: 70
Instructions: All questions are compulsory.
Figures to the right indicate full marks.
Draw neat diagram wherever necessary.
Q.1 Multiple choice questions: 14
Organic semiconductors are solids whose building blocks are
molecules.
pi-bonded covalent bonded
ionic bonded metallic bonded
OLED is made in a type semiconductor.
Separate Undistinguished
Distant Sandwich
The optical absorption edge of organic semiconductors is
5-4 eV 1.7-3 eV
1-1.5 eV 1-2 eV
Molecular weight is the of a molecule.
mass particle
ray drop
A 1s electron occupies the energy level the nucleus.
nearest far
constant none of these
Depletion layer is a region in a diode where no mobile charge carriers are
present
p-type n-type
P-N junction None of these
The energy difference between the HOMO and LUMO is termed the
energy gap low gap
HOMO-LUMO gap high gap
We can never reduce the nonradiative recombination but we can it.
stable keep constant
minimize maximize
OLED stand for
organic light emitting device organic laser emulation device
organ lagging evaluation device all of the above
10) Which of the following heterojunction type shows enhanced charge transfer

Type I Type II
Type III None of these
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11) A polymer is a large molecule, or macromolecule, composed of many
Repeated subunits Non-repeated subunits
Constant subunits Increased subunits
12) A transistor is a semiconductor device used to electronic signals
and electrical power.
Rectify Amplify
Magnify All of these
13) Data storage is the of information.
Recording Rejecting
Neglecting String
14) Polymer is a molecule composed of many repeated
Sub shell Atom
Particle Subunits
Q.2 Answer the following. (Any four)
Define orbitals.
What do you mean by excitons?
Define triplets.
What is meant by OLED?
Define diode.
08
Write notes on. (Any Two)
Thermochromism
Applications of OLED.
Advantages of WOLED.
06
Q.3 Answer the following. (Any Two)
Give a brief explanation on organic semiconductor.
Explain HOMO-LUMO levels is OLED.
Describe non-radiative recombination decay of excitons.
08
Answer the following. (Any one)
With a neat diagram explain singlets and triplets.
Give an brief explanation on fabrication technology of White Light Emitting
Device (WOLED)
06
Q.4 Answer the following. (Any Two)
Describe with a neat diagram, the fundamental process of PVDs.
Explain polymer heterojunctions.
Explain fundamental processes of field effect transistor.
10
Answer the following. (Any one)
Describe heterojunctions with nanocrystals.
Explain applications polymers based field-effect transistor.
04
Q.5 Answer the following. (Any two) 14
Describe with the help of neat diagram, principle of organic light emitting
devices (OLED).
With a neat diagram, explain electronic and optical processes of organic
semiconductor.
Describe with the help of a neat diagram fabrication process of organic thin
film transistor (OTFT).