Solution‐processed Tetrafluoroborate‐capped In2O3 Nanocrystal Thin‐Film Transistors

Colloidal oleic acid (OA) capped indium oxide nanocrystal (In2O3 NC) was synthesized by the hot injection method. Afterwards, the ligand exchange reaction between OA and nitrosyl tetrafluoroborate (NOBF4) afforded tetrafluoroborate‐capped indium oxide nanocrystals (In2O3‐BF4− NCs). In2O3‐BF4− NCs thin‐film transistor (TFT) devices were fabricated by spin coating, exhibiting an electron mobility of 7.3 × 10−3, 5 × 10−2, and 0.19 cm2/V/s for low‐temperature annealed In2O3‐BF4− NCs films at 80, 150, and 250 °C, respectively. An even higher mobility of 13.0 cm2/V/s was obtained by annealing the films at 350 °C, because of decreasing distance between the adjacent In2O3 NCs, enhancing the electronic coupling between the neighboring NCs on the NC film by the decomposition of inorganic ligand NOBF4. The temperature‐dependent behavior of the electron transport of In2O3‐BF4− NCs films annealed at different temperatures of 150, 250, and 350 °C for application in TFT device is also reported. We conclude that thermally activating electron transport mechanism through nearest neighbor hopping works for the In2O3 NC solid in the range from 223 to 323 K, and the activation energy decreases with increasing annealing temperatures.