Electric field induced color switching in colloidal quantum dot molecules at room temperature

TL;DR

This paper demonstrates a novel electric-field induced color switching in colloidal quantum dot molecules at room temperature, enabling reversible and intensity-preserving color changes at the single-particle level, with potential applications in displays and sensing.

Contribution

It introduces a new method for instantaneous, reversible color switching in quantum dot molecules using electric fields, overcoming previous spectral range and intensity limitations.

Findings

Reversible color switching without intensity loss

Electron wavefunction toggling between two emission centers

Potential for field sensing and color-tunable devices

Abstract

Colloidal semiconductor quantum dots are robust emitters implemented in numerous prototype and commercial optoelectronic devices. However, active fluorescence color tuning, achieved so far by electric-field induced Stark effect, has been limited to a small spectral range, and accompanied by intensity reduction due to the electron-hole charge separation effect. Utilizing quantum dot molecules that manifest two coupled emission centers, we present a novel electric-field induced instantaneous color switching effect. Reversible emission color switching without intensity loss is achieved on a single particle level, as corroborated by correlated electron microscopy imaging. Simulations establish that this is due to the electron wavefunction toggling between the two centers dictated by the electric-field and affected by the coupling strength. The quantum dot molecules manifesting two coupled emission centers may be tailored to emit distinct colors, opening the path for sensitive field sensing and color switchable devices such as a novel pixel design for displays or an electric field color tunable single photon source.