Multiexciton dynamics in infrared-emitting colloidal nanostructures probed by a superconducting nanowire single-photon detector

Published

September 30, 2012

Author(s)

Richard L. Sandberg, Lazaro A. Padilha, Mumtaz Qazilbash, Wan Ki Bae, Richard D. Schaller, Jeffrey M. Pietryga, Martin Stevens, Burm Baek, Sae Woo Nam, Victor I. Klimov

Abstract

Carrier multiplication (CM) is the process in which absorption of a single photon produces multiple electron-hole pairs. Here, we evaluate the effect of particle shape on CM efficiency by conducting a comparative study of spherical nanocrystal quantum dots (NQDs) and elongated nanorods (NRs) of PbSe using a time-resolved technique that is based on photon counting in the infrared using a superconducting nanowire single-photon photodetector (SNSPD). Due to its high sensitivity and low noise levels, this technique allows for accurate determination of CM yields, even with the small excitation intensities required for quantitative measurements, and the fairly low emission quantum yields of elongated NR samples. Our measurements indicate an up to 60% increase in multiexciton yields in NRs versus NQDs, which is attributed primarily to a decrease in the electron-hole pair creation energy. These findings suggest that shape control is a promising approach for enhancing the CM process. Further, our work demonstrates the effectiveness of the SNSPD technique for the rapid screening of CM performance in infrared nanomaterials.

Citation

ACS Nano

Volume

6

Issue

11

Pub Type

Journals

Download Paper

https://doi.org/10.1021/nn3043226

Local Download

Keywords

Single-photon detectors, quantum dots, carrier multiplication

Citation

Sandberg, R. , Padilha, L. , Qazilbash, M. , Bae, W. , Schaller, R. , Pietryga, J. , Stevens, M. , Baek, B. , Nam, S. and Klimov, V. (2012), Multiexciton dynamics in infrared-emitting colloidal nanostructures probed by a superconducting nanowire single-photon detector, ACS Nano, [online], https://doi.org/10.1021/nn3043226, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=911574 (Accessed October 26, 2025)