Cooperative Charging in a Nanocrystal Assembly Gated By Ionic Liquid

TL;DR

This paper investigates the capacitance behavior of a nanocrystal assembly gated by an ionic liquid, revealing that capacitance peaks occur at specific voltages where each nanocrystal gains an electron, indicating a quantized charging process.

Contribution

It demonstrates that the capacitance exhibits a series of delta-function peaks at critical voltages, a novel insight into the electrostatic behavior of nanocrystal assemblies under ionic liquid gating.

Findings

Capacitance peaks at specific gate voltages.

Each nanocrystal gains one electron at each critical voltage.

Capacitance is a sum of delta-functions at these voltages.

Abstract

In order to make a densely packed assembly of undoped semiconductor nanocrystals conductive, it is usually gated by a room temperature ionic liquid. The ionic liquid enters the pores of the super-crystal assembly under the influence of an applied voltage. We study the capacitance of such a device as a function of the gate voltage. We show that, counter-intuitively, the capacitance of the system is the sum of delta-functions located at a sequence of critical gate voltages. At each critical voltage every nanocrystal acquires one additional electron.