Flexible integrated diode-transistor logic (DTL) driving circuits based on printed carbon nanotube thin film transistors with low operation voltage

Abstract

Fabrication and application of hybrid functional circuits have become a hot research topic in the field of printed electronics. In this study, a novel flexible diode-transistor logic (DTL) driving circuit is proposed, which was fabricated based on a light emitting diode (LED) integrated with printed high-performance single-walled carbon nanotube (SWCNT) thin-film transistors (TFTs). The LED, which is made of AlGaInP on GaAs, is commercial off-the-shelf, which could generate free electrical charges upon white light illumination. Printed top-gate TFTs were made on a PET substrate by inkjet printing high purity semiconducting SWCNTs (sc-SWCNTs) ink as the semiconductor channel materials, together with printed silver ink as the top-gate electrode and printed poly(pyromellitic dianhydride-co-4,4′-oxydianiline) (PMDA/ODA) as gate dielectric layer. The LED, which is connected to the gate electrode of the TFT, generated electrical charge when illuminated, resulting in biased gate voltage to control the TFT from “ON” status to “OFF” status. The TFTs with a PMDA/ODA gate dielectric exhibited low operating voltages of ±1 V, a small subthreshold swing of 62–105 mV dec⁻¹ and ON/OFF ratio of 10⁶, which enabled DTL driving circuits to have high ON currents, high dark-to-bright current ratios (up to 10⁵) and good stability under repeated white light illumination. As an application, the flexible DTL driving circuit was connected to external quantum dot LEDs (QLEDs), demonstrating its ability to drive and to control the QLED.