Metal oxide doped organic thin film transistors: a comprehensive review

In recent years, organic thin film transistors (OTFTs) have been gaining widespread interest for electronic displays, circuits and sensors over traditional silicon-based transistors due to their unique properties such as low cost, mechanical and electrical stability, low-temperature processability and large-area processability. They are widely used in applications pertaining to flexible displays, wearable devices, radio frequency identification (RFID) tags, e-skin, biosensors, and flexible integrated circuits. However, organic thin film transistors are still inferior to silicon-based technologies, trailing behind in several critical performance metrics such as low mobilities and high operational voltages. These challenges can be mitigated using metal oxides, which, owing to their high work function and stability, can enhance the parameters of OTFT devices. This review aims to provide insights into the usage of metal oxides in organic thin film transistors and highlight their contribution as hole injection layers (HILs), charge transport complexes (CTCs), bilayer source–drain (S–D) electrodes and gate dielectrics.