Low-temperature, high-performance solution-processed metal oxide thin-film transistors formed by a ‘sol–gel on chip’ process

Abstract

At present there is no ‘ideal’ thin-film transistor technology for demanding display applications, such as organic light-emitting diode displays, that allows combining the low-temperature, solution-processability offered by organic semiconductors with the high level of performance achievable with microcrystalline silicon¹. N-type amorphous mixed metal oxide semiconductors, such as ternary oxides M_x¹M_y²O_z, where M¹ and M² are metals such as In, Ga, Sn, or Zn, have recently gained momentum because of their high carrier mobility and stability^2,3 and good optical transparency, but they are mostly deposited by sputtering. So far no route is available for forming high-performance mixed oxide materials from solution at low process temperatures s-orbitals are relatively insensitive to the presence of structural disorder and high charge carrier mobilities are achievable in amorphous structures². Here we report the formation of amorphous metal oxide semiconducting thin-films using a ‘sol–gel on chip’ hydrolysis approach from soluble metal alkoxide precursors, which affords unprecedented high field-effect mobilities of 10 cm² V⁻¹ s⁻¹, reproducible and stable turn-on voltages V_on≈0 V and high operational stability at maximum process temperatures as low as 230 °C.