Tin Dioxide Electrolyte-Gated Transistors Working in Depletion and Enhancement Modes

Metal oxide semiconductors are interesting for next-generation flexible and transparent electronics because of their performance and reliability. Tin dioxide (SnO₂) is a very promising material that has already found applications in sensing, photovoltaics, optoelectronics, and batteries. In this work, we report on electrolyte-gated, solution-processed polycrystalline SnO₂ transistors on both rigid and flexible substrates. For the transistor channel, we used both unpatterned and patterned SnO₂ films. Since decreasing the SnO₂ area in contact with the electrolyte increases the charge-carrier density, patterned transistors operate in the depletion mode, whereas unpatterned ones operate in the enhancement mode. We also fabricated flexible SnO₂ transistors that operate in the enhancement mode that can withstand moderate mechanical bending.