Fully inkjet printed flexible SWCNT based TFT: Impact of traps on characteristics

Fully inkjet printed thin film transistors (TFTs) are a key demand for large area flexible circuits. We demonstrate flexible TFTs and logic gates, in which all layers are inkjet printed using polymer wrapped semiconducting single walled carbon nanotubes (SWCNTs) ink as a channel layer and PVP ink as a dielectric layer on a flexible PEN substrate. The bottom gate, source, and drain electrodes were inkjet-printed with silver (Ag) ink. These inkjet printed semiconducting SWCNT-TFTs show an excellent mobility of 30 cm2/(Vs), small SS of 125 mV/dec, and good on/off ratio >104. We study the impact of hysteresis in the IDS–VGS curve of the TFT, which is evidence for a large number of traps controlling the device characteristics. We quantify the impact of trapped charge on device characteristics by studying the sweep rate dependence of hysteresis. Furthermore, several preliminary applications are explored by designing flexible inverters, NAND gates, and NOR gates using these TFTs. The value of gain in the inverter was achieved to be 3.0.