Electron tunneling from colloidal CdSe quantum dots to ZnO nanowires studied by time-resolved luminescence and photoconductivity experiments

TL;DR

This study investigates electron tunneling from CdSe quantum dots to ZnO nanowires using time-resolved luminescence and photoconductivity, revealing how linker molecules influence tunneling efficiency and photocurrent enhancement.

Contribution

It demonstrates controlled electron tunneling from QDs to nanowires and correlates linker chemistry with tunneling rates and photocurrent improvements.

Findings

Electron tunneling reduces PL decay time.

Photocurrent is significantly enhanced by QD attachment.

Tunneling rate varies with different linker molecules.

Abstract

CdSe quantum dots (QDs) with different organic linker molecules are attached to ZnO nanowires (NWs) to study the luminescence dynamics and the electron tunneling from the QDs to the nanowires in time-resolved photoluminescence (PL) and photoconductivity measurements. The PL transients of the QD luminescence indicate two different recombination channels: the direct recombination inside the QD core and the recombination via QD surface defect states. After linking the QDs to the ZnO NW surface, photo-induced electron tunneling from an excited state of the QD into the conduction band of the nanowire becomes visible by a clear decrease of the PL decay time. Efficient electron tunneling is confirmed by a strong enhancement of the photocurrent through the functionalized nanowires in which the tunneling rate can be controlled by using different organic linker molecules.