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Highlights in Chemical Technology

Chemical technology news from across RSC Publishing.

New spin on electronics production

24 October 2008

Chemists have taken a significant step closer to the goal of cheap, flexible and printable organic electronic displays, an idea they claim could revolutionise the electronics industry.

A Japanese team, led by Tetsuo Okujima and Noboru Ono at Ehime University, Matsuyama, synthesised thin films of phthalocyanine (Pc) and the related compound, naphthalocyanine (Nc), without using costly ultra-high vacuum techniques.

Thin film preparation

Semiconducting insoluble thin films are prepared by spin-coating soluble molecules then heating the thin film to release the volatile solubility-imparting groups

Pc and Nc are insoluble so Ono and Okujima added functional groups to the molecules to improve solubility. They then dissolved the molecules in an organic solvent and spun the solution rapidly on a glass plate, evaporating the solvent and forming a thin film of the molecules on the glass. When they heated the films, a retro Diels-Alder reaction released the volatile solubility-imparting groups. The final films were totally insoluble and acted as semiconductors.

"This work represents a step forward to realising organic semiconductor-based, low-cost, printable and flexible electronics"
- Jerzy Kanicki, University of Michigan, US
The group then made an organic field-effect transistor (OFET) using the films. OFETs are essential components of flexible organic electronic displays, which are starting to appear on the market but are hampered by high-cost production.

Okujima says that his work could result in organic electronic devices becoming cheaper and easier to make. 'This is the first example of solution-processed parent Pc- or Nc-based OFETs which are fabricated easily, at low-cost and over a large area,' he explains.

Jerzy Kanicki, an expert in organic electronics at the University of Michigan, Ann Arbor, US, is impressed by the synthesis. 'This work represents a step forward to realising organic semiconductor-based, low-cost, printable and flexible electronics,' he says. 'From this we can further confirm that the versatility of organic synthetic methods and new soluble precursors allows seemingly infinite flexibility in tuning the electrical properties of OFETs.'

James Hodge

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Link to journal article

Soluble precursors of 2,3-naphthalocyanine and phthalocyanine for use in thin film transistors
Atsuko Hirao, Taiji Akiyama, Tetsuo Okujima, Hiroko Yamada, Hidemitsu Uno, Yoshimasa Sakai, Shinji Aramaki and Noboru Ono, Chem. Commun., 2008, 4714
DOI: 10.1039/b811674a

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