Semiconductors have traditionally been made from rigid, fragile materials.
In recent years, however, research into semiconductors that can bend and stretch has been advancing rapidly.

 

This is made possible by organic semiconductors and printed electronics technology.
Unlike conventional silicon semiconductors, these materials are soft, lightweight, and relatively simple to manufacture.

Organic semiconductors are materials in which molecules or polymers composed primarily of carbon conduct electricity. Rather than the free electrons found in metals, conductivity is carried by the π-electrons of the molecules.

 

Representative materials include:

・Polythiophene-based compounds (such as P3HT)

・Pentacene

・Conjugated polymers (such as PPV and PTAA)

・Fullerene derivatives (such as PCBM, used in solar cells)

Compared with inorganic semiconductors, these materials are more flexible and can be processed at low temperatures.

Organic and flexible semiconductors can be manufactured using low-temperature processes such as printing, coating, and vapor deposition.

 

Main substrate materials:

・Plastic films (PET, PEN, PI)

・Specialty substrates such as paper, rubber, and fabric

 

Main manufacturing methods:

・Inkjet printing

・Gravure printing

・Spin coating

・Roll-to-roll (R2R) processing

 

Because these methods don’t require the high temperatures and high vacuum conditions used in silicon manufacturing, semiconductors can effectively be produced much like items in a printing factory.

Advantages

・Lightweight, flexible, and inexpensive

・Easy to manufacture over large areas

・Low-temperature processing reduces environmental impact

・High design freedom, allowing devices to be bent or adhered to surfaces

 

Disadvantages

・Low electron mobility (roughly 1/100 to 1/1000 that of silicon)

・Vulnerable to humidity and oxygen, resulting in a shorter lifespan

・Difficult to operate at high temperatures

 

As a result, these materials are best suited to applications that prioritize usability and shape flexibility over raw performance.

1.Flexible displays Used in OLED smartphones and foldable displays, as well as curved monitors and smartwatches.

2.Electronic paper and electronic tags Ultra-low-power, lightweight, printable display elements.

3.Wearable devices Sensors worn on the skin to measure body temperature, heart rate, sweat composition, and more — used in medical monitoring and rehabilitation equipment.

4.Printed sensors Used to detect pressure, gas, light, humidity, and more, with growing demand in food, agriculture, and logistics.

5.Organic photovoltaics (OPV) Lightweight, bendable solar cells that can be applied to buildings, clothing, drones, and more.

The places where electricity can be used are expanding from rigid solids to virtually any surface.

・Manufacturing temperatures are relatively low, around 100–200°C, resulting in lower CO₂ emissions.

・The resulting structures are relatively easy to recycle at end of life.

・Manufacturing equipment costs can be less than one-tenth those of silicon semiconductor equipment.

These qualities have earned organic semiconductors attention as a form of green semiconductor technology.

・Low carrier mobility makes these materials unsuitable for high-speed computing devices.

・Vulnerability to moisture and oxygen makes sealing technology essential.

・Ensuring long-term reliability remains difficult, typically limited to a few thousand hours of operation.

・Controlling film thickness and resistance variation during mass production remains a challenge.

Current research is focused less on maximizing performance and more on achieving low cost and mass production.

・Hybridizing organic and inorganic semiconductors (such as organic-inorganic perovskites).

・Developing stretchable transistors (stretchable TFTs).

・Research into electronic skin (e-skin) that leverages biocompatibility.

・Self-powered sensors that pair with energy harvesting from light, vibration, or heat.

Organic semiconductors are developing into a technology that sits closer to people and the natural environment.

・An era is approaching in which these materials will be embedded not only in displays and medical devices, but also in clothing, skin, and walls.

・They are evolving into interface materials that bridge people and machines, and the digital and natural worlds.

・By the 2030s, a single film may effectively become an electronic device in its own right.

・Organic and flexible semiconductors enable flexible electronic devices at low temperature and low cost.

・While they lag behind silicon in performance, they offer high design freedom and strong environmental adaptability.

・They are opening up new application areas in wearables, IoT, medicine, and agriculture.

・Going forward, these materials are set to accelerate their integration into society as “semiconductors that stay close to people.”

1.What is the main component of organic semiconductors?

2.What are the main strengths of organic semiconductors?

3.What are the main challenges they face?

 

Column Supervisor: Koji Kakumoto (Otis Group Co., Ltd.)

After studying abroad and working in planning and development at a trading company, he joined Otis Group Co., Ltd. in 2011. While primarily working in the Corporate Planning Department, he has also served concurrently in manufacturing and technical divisions, and since 2018 has served as Representative Director, working to drive business growth and strengthen the organization.

 

This article is a general technical explanation intended for educational purposes and does not refer to any specific company, product, or technology.