OFET: Advantages and Disadvantages of Organic Field Effect Transistors

This page explores the pros and cons of OFETs (Organic Field Effect Transistors), highlighting their benefits and drawbacks.

What is an OFET?

Introduction: OFETs utilize organic semiconductor materials within their channel. The first OFET, introduced in 1986, was based on a film made of electrochemically grown polythiophene. Subsequently, they were manufactured using aromatic and conjugated materials, including both small molecules and polymers.

Small molecule examples include pentacene, rubrene, tetracene, and tetracyanoquinodimethane. Common polymers include polyfluorene and polydiacetylene.

OFETs find applications in diverse areas such as smart textiles, portable compact screens, skin cancer treatments, bioelectronics, and biomedicines.

Figure: OFET Schematic

The figure illustrates a typical OFET schematic. As shown, it comprises three terminals: source, drain, and gate. It also incorporates a semiconductor layer and an insulating layer positioned between the gate and the semiconductor.

There are two primary OFET device configurations:

• Top Contact Based: Source and drain electrodes are evaporated onto the top of the organic material.
• Bottom Contact Based: Source and drain electrodes are evaporated onto the dielectric before the organic semiconductor deposition.

Applying voltage to the gate induces an electric field through the dielectric material. This leads to the formation of an accumulation layer of charges at the interface of the deposited semiconductor.

OFET characteristics can be demonstrated using either a transfer characteristic or an output characteristic. The transfer characteristic is obtained by varying Vgs while keeping Vds constant. The output characteristic is constructed by varying Vds while keeping Vgs constant.

Benefits or Advantages of OFET

The following are the benefits or advantages of OFET:

• Affordable Price: Low-cost manufacturing makes them readily accessible.
• Large Area Coverage: Enables fabrication over expansive surfaces.
• Greater Flexibility: Can be manufactured on flexible substrates.
• Tunable Electronic Materials: Readily available materials allow for customization of electronic properties.
• Lightweight: Contributes to the portability and reduced weight of devices.
• Material Selection: Can be manufactured from a large selection of materials.

Drawbacks or Disadvantages of OFET

The following are the disadvantages of OFET:

• Optimization Required: Devices need optimization to deliver reliable performance.
• Thermal Stability: Susceptible to degradation at high temperatures.
• Chemical Stability (Oxidation): Can be affected by oxidation in certain environments.