Organic transistors were first developed in 1986 and use organic molecules rather than silicon as the active material. They have advantages over traditional silicon transistors such as being lightweight, flexible, cheap to produce, and compatible with solution processing and plastic substrates. Key parameters for organic transistors include mobility, on-off ratio, and threshold voltage. Device design can be top contact or bottom contact, with top contact having superior performance. Pentacene-based organic transistors currently have the best field effect mobility. Improving the dielectric, electrodes, and reducing contact resistance and leakage current can further increase performance. Organic transistors have applications in flexible displays, memory, sensors, and more.

2. Outline
1. Motivation and introduction
2. Types and mechanism
3. Different advancement
4. Vacuum and solution based processes
5. Applications

3. What and why an organic transistor?
• First Organic Transistor - 1986
• Using organic molecules (Polymers) rather than silicon for their active
material.
• Semiconductor
• Advantages
1. Light weight,
2. flexible,
3. Cheap
4. Solution Processing  Photolithographic patterning
5. lower temperature manufacturing (60-120° C)
6. Print-able Organic Transistors
7. compatibility with plastic substances
8. foldable & light weight
(Tsumura et al. 1986.
B. kumar et al. 2014.

4. Device Structure
• Important parameters Key Parameters
– Mobility (µ ≈ 1-10 cm2/vs)
– On-Off Ratio
• Suitable (106)
– Threshold voltage
– Colin Rees et al. 2005

5. Device design
• Top contact
• Bottom contact
Top contact devices have superior
performance sue to low contact
resistance between the source and
active layer.
Roichman et al. 2004

6. Comparison of different OTFTs
Comparative plot of the OTFTs
which are based on different
materials is shown.
Different materials have been assed
to improve the device performance.
Among all the materials pentacene
based organic thin film transistors or
electronic devices have best field
effect mobility.
Feng et al. 2015,
B. kumar et al 2014

7. Interlayer between electrode and insulator
Capacitance and leakage current of the device is reduced.
J. Yoon et al. 2013
C. Chu et al.2005

8. High Performance OTFT with a metal/metal oxide
bilayer electrode
• TMO helps in controlling work
function and charge injection
properties
• Reduces contact barrier and
prevents the diffusion
*Chih-Wei Chu, Sheng-Han Li, Chieh-Wei Chen, Vishal Shrotriya, and Yang Yang, High-performance organic thin-film
transistors with metal oxide/metal bilayer electrode, Applied Physics Letters 87, 193508 (2005);

9. Other key factors to improve Field Effect Mobility
• Higher the dielectric constant of insulator higher will be the field effect mobility
• k↑ → Polarization↑ → Carrier Density↑ → Mobility↑
• Dielectric roughness also effect the field effect mobility
• Roughness↓ → Mobility↑
• Higher the contact resistance of the insulator with the electrodes will lower the
field effect mobility. Penetration of the electrode into the dielectric also effect the
mobility, higher the penetration lower will be the mobility
• Au coated (PEDOT/PSS) Charge Injection↑ → Contact Resistance↓ → mobility↑
• H. H. Lee et al. Appl. Phys. Lett. (2005)
• 18- R. Schroeder et al, Appl. Phys. Letts (2005)

10. Vacuum Processes Solution Processes
PECVD , PVD, LPCV, OVPD
Conventional Process
Provides advantage of Deposition Rate
Monitoring
Controlled
Costly
Colin et al. 2011.
Coating by Spray, spin
Electrodeposition
Electroless deposition
Also includes printing processes
Very lost Cost
Flexible
Can be used for large area applications
Efficiency few orders

11. Flexible
OLED
Flexible
LCD
Organic
Memory
Image
Sensor
Bio
Sensor
Organic
Laser
Smart Card
RFID Tag
E-paper
OTFT
IC
Technology
Optical
Technology
Bio
Technology
Apparel
Technology
Sensor
Technology
Memory
device
Technology
LCD
Technology
OLED
Technology
E-Paper
Technology
Smart
Textile
Application of Organic TFT

12. Any Question?