This is said to be the highest frequency reported to date for a unipolar ring oscillator fabricated using a solution-processed organic semiconductor and gate dielectric. It is also expected that with minor optimisation of the circuit design, oscillator frequencies above 1MHz could be attained.
Integrated circuits based on OTFTs have been in development for over 15 years with development scientists working on both the speed and complexity of integrated circuits for a range of electronics applications. However, one of the main barriers to the growth of printed electronic circuits was the ability to manufacture circuits using high-throughput, solution-coating techniques with the necessary semiconductor performance to allow fast logic circuits to be realised in standard digital circuits such as ring oscillators.
This result demonstrates that this historic barrier no longer exists, opening the door to a range of application possibilities. For instance, with the emergence of the Internet of Things, one market requirement that has not been met is for low-cost, thin, flexible and disposable RFID and NFC tags for the transmission of data from devices, sensors or objects. To achieve the necessary bit rate of 53kbits/s for a RFID or NFC device operating at the standardised frequency of 13.6MHz, a stage gate delay in the logic of less than 400ns is needed: Two times slower than SmartKem’s ring oscillator.
A more immediate application is as a TFT backplane platform for the manufacture of conformal LCD and flexible AMOLED displays. SmartKem says narrow bezels can now be achieved by the use of ‘integrated gate drivers’ fabricated on the display backplane. Whilst it was once thought that this could only be achieved using inorganic materials such as LTPS, this result shows that tru-FLEX would allow the manufacture of integrated gate drivers that would not only drive 4K2K displays, but would also offer true physical flexibility.
