Spin Selective Charge Transport in Quantum Dots

  • By Aude Marjolin
  • 21 July 2016

The latest study in David Waldeck's group, published in ACS Nano Letters, demonstrates that chiral imprinted CdSe quantum dots (QDs) can act as spin selective filters for charge transport.

Semiconductor quantum dots remain an attractive material for photovoltaics because of their solution processability and potential for multiple exciton generation; enabling a promising route for the realization of low cost, high efficiency solar cells. In addition, previous experiments have shown that spin selective charge transport can enhance the photoconversion efficiencies of organic bulk heterojunctions. The present work therefore explores whether chiral induced spin selectivity (CISS) can be used as an alternative approach to affect charge transport through quantum dot films and demonstrates that quantum dot thin films composed of chiral semiconductors preferentially transmit electrons with a particular spin orientation.

In the study, chiral cysteine passivated CdSe QDs are synthesized, and their spin dependent charge transport properties are measured using magnetic conductive probe atomic force microscopy (mCP-AFM) and magnetoresistance (MR) measurements. The findings show that the individual QDs and the QD films act as spin filters. Such QD assemblies may prove useful for creating spin selective conduction pathways and for spin driven quantum dot sensitized photovoltaic devices.

The spin filtering properties of chiral quantum dots may prove useful in future applications, for example, photovoltaics, spintronics, and other spin-driven devices.

Read the full article here.