Modulating Donor-Acceptor Transition Energies in Phosphorus-Boron Co-Doped Silicon Nanocrystals via X- and L-Type Ligands

Nathan Neale, Gregory Pach, Gerard Carroll, Hanyu Zhang

Research output: Contribution to journalArticlepeer-review

10 Scopus Citations


In this work, we explore the effect of ligand binding groups on the visible and NIR photoluminescent properties within phosphorus-boron co-doped silicon nanocrystals (PB:Si NCs) by exploiting both the X-type (covalent) and L-type (Lewis donor molecule) bonding interactions. We find that the cooperative nature of both X- and L-type bonding from alkoxide/alcohol, alkylamide/alkylamine, and alkylthiolate/alkylthiol on PB:Si NCs results in photoluminescence (PL) energy blue shifts from the as-synthesized, hydride-terminated NCs (PB:Si-H) in excess of 0.4 eV, depending on the surface termination. These PL blue shifts appear greatest in the most strongly confined samples with diameters <4 nm where the surface-to-volume ratio is high and, therefore, the ligand effects are most pronounced. A correlation between the donor group strength (either X-type or L-type) and the degree of D-A state modulation is found, and the proportion of the PL blue shift from the X- and L-type interactions is quantified. Raman spectroscopy is used to provide additional evidence of the strength of the L-type donor groups. Additionally, we probe how the nature of the ligand chemistry affects the radiative lifetime and PL efficiency and find that the ligands do not significantly change the D-A emission dynamics, and all samples retain the long 50-130 μs lifetimes characteristic of these transitions. Finally, we describe three mechanisms that operate to affect the D-A recombination energies: (1) X-type ligands that modulate the PB:Si-X NC wavefunction; (2) L-type ligands that perturb the donor and acceptor states via a molecular orbital theory picture; and (3) X- and L-type ligands that cause a dielectric increase around the PB:Si NC core, which provides Coulomb screening and modulates the donor and acceptor states even further.

Original languageAmerican English
Pages (from-to)201-216
Number of pages16
JournalFaraday Discussions
StatePublished - 1 Jun 2020

Bibliographical note

Publisher Copyright:
© The Royal Society of Chemistry.

NREL Publication Number

  • NREL/JA-5900-75122


  • L-type ligands
  • nanocrystal
  • solar-photochemistry
  • transition energies
  • X-type ligands


Dive into the research topics of 'Modulating Donor-Acceptor Transition Energies in Phosphorus-Boron Co-Doped Silicon Nanocrystals via X- and L-Type Ligands'. Together they form a unique fingerprint.

Cite this