Spin Selective Charge Transport through Cysteine Capped CdSe Quantum Dots

Abstract

This work demonstrates that chiral imprinted CdSe quantum dots (QDs) can act as spin selective filters for charge transport. The spin filtering properties of chiral nanoparticles were investigated by magnetic conductive-probe atomic force microscopy (mCP-AFM) measurements and magnetoresistance measurements. The mCP-AFM measurements show that the chirality of the quantum dots and the magnetic orientation of the tip affect the current-voltage curves. Similarly, magnetoresistance measurements demonstrate that the electrical transport through films of chiral quantum dots correlates with the chiroptical properties of the QD. The spin filtering properties of chiral quantum dots may prove useful in future applications, for example, photovoltaics, spintronics, and other spin-driven devices.

Imprinting Chirality onto the Electronic States of Colloidal Perovskite Nanoplatelets

“…The signal generated from 300–350 nm is attributed to the excitation of a charge transfer band between the chiral ligand and the NP surface. Comparable chiroptical features are present in ligand solutions of S‐ or R‐PEA with lead bromide in the absence of NPs (see Figure S3 in the Supporting Information), and a similar phenomenon was previously found for chiral ligands coordinated to CdSe and CdTe nanoparticles . The bisignate peak between 400 and 450 nm overlaps with the maximum of the perovskite NPs' exciton absorption (see Figure a,b) and indicates that the ligand imprints its chirality onto the NP's electronic structure.…”

“…Perovskite semiconductors offer extraordinary promise for next generation optoelectronic materials because of their desirable characteristics of color tunability (through halide composition and quantum confinement effects), long carrier lifetime and diffusion lengths, and high electron/hole mobility; recent applications include light emitting diodes, lasers, and photovoltaics . In addition to spin‐mediated transport processes and chiral memory applications, which arise from the chiral induced spin selectivity effect, chiro‐optical semiconductor nanomaterials are particularly interesting for stereoselective synthesis and as circularly polarized light sources . Recent work on CH 3 NH 3 PbBr 3 perovskite materials shows strong spin–orbit coupling of the electronic states, suggesting that chiral perovskites might display interesting spin polarization properties.…”

Molecular Semiconductors for Logic Operations: Dead‐End or Bright Future?

“…One plausible explanation comes from the chiral‐induced spin selectivity (CISS) effect, i.e., the filtering of electrons depending on their spin by chiral molecules . CISS has been observed for a variety of systems: poly(thiophene) with chiral side‐chains, cysteine, oligopeptides, protein, carbon nanotubes functionalized with single‐stranded DNA, chiral self‐assembled monolayer, and even helicenes . CISS can be intuitively understood.…”

Chiral 2D Colloidal Semiconductor Quantum Wells

“…Colloidal semiconductor nanoparticles with a chiral optical response are a new subclass of nanomaterials which have recently attracted significant attention due to a variety of potential applications . These nanostructures combine the tunability and control afforded by quantum confinement effects with unique properties which render them as potential candidates for use in chiral sensing, asymmetric catalysis, quantum optics, and spintronics . A limited range of semiconductor nanocrystals, such as cinnabar HgS, exhibit a chiral crystal structure and are therefore intrinsically chiral .…”