Solution-Processed Ambipolar Organic Thin-Film Transistors by Blending p- and n-Type Semiconductors: Solid Solution...

Area of Science:

• Materials Science
• Organic Electronics
• Semiconductor Physics

Background:

• Organic thin film transistors (OTFTs) are crucial for flexible electronics.
• Achieving balanced hole and electron transport (ambipolarity) in OTFTs is challenging.
• Current p-n blends often suffer from phase separation, limiting performance.

Purpose of the Study:

• To introduce solid solutions of p- and n-type organic semiconductors as a novel p-n blend for solution-processed ambipolar OTFTs.
• To compare the performance of solid-solution films with microphase-separated films.
• To investigate the tunability of charge carrier mobilities in the solid solutions.

Main Methods:

• Fabrication of OTFTs using solid solutions of silylethynylated tetraazapentacene (acceptor) and silylethynylated pentacene (donor).
• Comparison with microphase-separated blends of the same materials.
• Characterization of electrical properties, including hole and electron mobilities.
• Analysis of optical properties and photoeffects.

Main Results:

• Solid solutions of the organic semiconductors function as ambipolar semiconductors.
• Hole and electron mobilities are tunable by adjusting the ratio of donor and acceptor in the solid solution.
• OTFTs with a 1:1 ratio (0.5:0.5) exhibit balanced mobilities comparable to state-of-the-art devices.
• Solid solutions show different optical absorption and photoeffects compared to microphase-separated blends due to molecular-level mixing.

Conclusions:

• Solid solutions of organic semiconductors offer a promising new strategy for creating high-performance ambipolar OTFTs.
• Molecular-level mixing in solid solutions enables tunable charge transport properties.
• This approach provides an alternative to microphase-separated blends, with distinct optical characteristics.