Title: Negligible Electronic Interaction between Photoexcited Electron–Hole Pairs and Free Electrons in Phosphorus–Boron Co-Doped Silicon Nanocrystals

Abstract

Phosphorus (P) and boron (B) co-doped Si nanocrystals (NCs) have raised interest in the optoelectronic industry due to their electronic tunability, optimal carrier multiplication properties, and straightforward dispersibility in polar solvents. Yet a basic understanding of the interaction of photoexcited electron-hole (e-h) pairs with new physical features that are introduced by the co-doping process (free carriers, defect states, and surface chemistry) is missing. Here, we present the first study of the ultrafast carrier dynamics in SiO2-embedded P-B co-doped Si NC ensembles using induced absorption spectroscopy through a two-step approach. First, the induced absorption data show that the large fraction of the dopants residing on the NC surface slows down carrier relaxation dynamics within the first 20 ps relative to intrinsic (undoped) Si NCs, which we interpret as enhanced surface passivation. On longer time-scales (picosecond to nanosecond regime), we observe a speeding up of the carrier relaxation dynamics and ascribe it to doping-induced trap states. This argument is deduced from the second part of the study, where we investigate multiexciton interactions. From a stochastic modeling approach we show that localized carriers, which are introduced by the P or B dopants, have minor electronic interactions with the photoexcited e-h pairs. This ismore » understood in light of the strong localization of the introduced carriers on their original P- or B-dopant atoms, due to the strong quantum confinement regime in these relatively small NCs (<6 nm).« less

Authors:

Limpens, Rens  ^[1];

• Search DOE PAGES for author "Limpens, Rens"
• Search DOE PAGES for ORCID "0000-0002-2417-9389"

Fujii, Minoru  ^[2];

• Search DOE PAGES for author "Fujii, Minoru"
• Search DOE PAGES for ORCID "0000-0003-4869-7399"

Neale, Nathan R.  ^[1];

• Search DOE PAGES for author "Neale, Nathan R."
• Search DOE PAGES for ORCID "0000-0001-5654-1664"

Gregorkiewicz, Tom  ^[3]

• Search DOE PAGES for author "Gregorkiewicz, Tom"
• Search DOE PAGES for ORCID "0000-0003-2092-8378"

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+ Show Author Affiliations

1. National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, United States
2. Department of Electrical and Electronic Engineering, Kobe University, Rokkodai, Nada, Kobe 657-8501, Japan
3. Van der Waals-Zeeman, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands

Publication Date:

Mon Mar 05 00:00:00 EST 2018

Research Org.:

National Renewable Energy Laboratory (NREL), Golden, CO (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences, and Biosciences Division

OSTI Identifier:

1427876

Alternate Identifier(s):

OSTI ID: 1435709; OSTI ID: 1508756

Report Number(s):

NREL/JA-5900-70658
Journal ID: ISSN 1932-7447

Grant/Contract Number:  

AC36- 08GO28308; AC36-08GO28308

Resource Type:

Published Article

Journal Name:

Journal of Physical Chemistry. C

Additional Journal Information:

Journal Name: Journal of Physical Chemistry. C Journal Volume: 122 Journal Issue: 11; Journal ID: ISSN 1932-7447

Publisher:

American Chemical Society

Country of Publication:

United States

Language:

English

Subject:

14 SOLAR ENERGY; 36 MATERIALS SCIENCE; ultrafast; phosphorous-boron; nanocrystals