A digital library for a flexible low-voltage organic thin-film transistor technology

This paper presents the design, fabrication and characterization of digital logic gates, flip-flops and shift registers based on low-voltage organic thin-film transistors (TFTs) on flexible plastic substrates. The organic transistors are based on the p-channel organic semiconductor dinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]thiophene (DNTT) and have channel lengths as short as 5 μ m and gate-to-contact overlaps of 20 μ m. The organic TFT is modeled which allows us to simulate different logic gate architectures prior to the fabrication process. In this study, the zero-VGS, biased-load and pseudo-CMOS logic families are investigated, where their static and dynamic operations are modeled and measured. The inverter and NAND gates use channel length of 5 μ m and operate with a supply voltage of 3 V. Static and dynamic master-slave flip-flops based on biased-load and pseudo-CMOS logic are designed, fabricated and characterized. A new design for biased-load dynamic flip-flops is proposed, where transmission gate switches are implemented using only p-channel transistors. 1-stage shift registers based on the new design and fabricated using TFTs with a channel length of 20 μ m operate with a maximum frequency of about 3 kHz.