Compact Organic Complementary D-Type Flip-Flop Circuits Fabricated with Inkjet Printing

Organic thin‐film transistors (OTFTs) have received significant consideration in recent years for potential deployment in low‐cost and large‐area printed electronics. D‐type flip‐flop (D‐FF) circuits are one of the most important logic gates for data processing and storage in such applications. Previous work has reported on NAND‐based organic D‐FF circuits. Although the demonstrated printed circuits exhibit low voltage operation at 10 V, each D‐FF circuit requires 34 TFT devices and occupies an area of 192 mm 2 per D‐FF circuit. This paper demonstrates inkjet‐printed organic D‐FF circuits with a compact circuit design using clocked inverters and transmission gates and compares the occupied area and the circuit performance with those of NAND‐based organic D‐FF circuits. The compact organic D‐FF circuits require only 18 OTFT devices, and can use 60% less area than NAND‐based organic D‐FF circuits fabricated by the same process. In addition, the compact organic D‐FF circuits exhibit a shorter propagation delay time than the NAND‐based D‐FF circuits. The mechanism for the shortened delay time will be discussed in detail, based on SPICE simulations. These results demonstrate the high potential of these compact organic D‐FF circuits in printable electronics.