Figure 1.

Electrochemical setup used to apply voltage and monitor PL from QDs. (a) Confocal microscope and electrochemical cell used to evaluate a potential voltage sensor. QDs are deposited at the working electrode/electrolyte interface of an electrochemical cell with voltage applied between the ITO and Pt electrodes, using a potentiostat. Simultaneously, samples are excited with a 532 nm laser (∼1 μm beam size) with emission collected through the ITO back surface. (b) Cartoon schematic of device cross-section shown alongside COMSOL simulation depicting the variation in potential across the device for a positive voltage applied to the ITO. Shown in the case of 1 mM KNO₃, the potential is shown to drop predominately across the QD and extended double layer with the Ta₂O₅ layer (dielectric) experiencing little to no potential drop. (c) Cross-sectional TEM image of chip used for applying a voltage to QDs. The electrochemical device consists of an ITO bottom electrode atop which is evaporated ∼300 nm of high-κ dielectric (Ta₂O₅); QDs sit smoothly at the electrolyte (KNO₃) dielectric interface as shown above.