Improvement and Applications of Large-Area Flexible Electronics with Organic Transistors

Abstract

With the advantage of the circuit integration on a plastic thin film with a low-temperature, low-cost, printable or printing process, organic transistor is widely recognized as a promising candidate for realizing large-area flexible electronics such as displays [1–3], power/data transmission sheets [4,5], and sensor arrays [6–8]. The technology of organic transistors has been significantly improving. 96First of all, the improvement of process maturity and yield realizes highly integrated circuits such as an 8-bit microprocessor and analog-to-digital converters (ADCs) [9–11]. For the low-voltage operation, a self-assembled monolayer (SAM) technology lowered the operation voltage toward 1 V [12]. The fastest n-type metal–oxide–semiconductor (nMOS) transistors with C10-DNTT [13] achieved the signal propagation delay of 420 ns per stage in the ring oscillator at supply voltage of 3 V [14]. For high-frequency applications, some radio-frequency identifications (RFIDs) have been proposed [15,16]. Those are implemented with only high-voltage p-type metal–oxide–semiconductor (pMOS) transistors because the mobility of nMOS transistors is much slower than that of pMOS. To address this issue, a hybrid organic (pMOS)/solution-processed metal–oxide (nMOS) RFID tag was recently proposed [17]. However, the operating speed of organic transistors is still not sufficient for the operation at hundreds megahertz order even if high voltages of 20 V or higher are supplied to the circuit. Therefore, the system-level integration of organic transistors and silicon complementary metal–oxide–semiconductor (CMOS) circuits is one of the practical solutions [18].