Time-Resolved Stark Spectroscopy in CdSe Nanoplatelets

Exciton Binding Energy, Polarizability, and Field-Dependent Radiative Rates

Journal article (2016)

Authors

Riccardo Scott Technical University of Berlin
A.W. Achtstein ChemE/Opto-electronic Materials - AS , Technical University of Berlin
Anatol V. Prudnikau Belarusian State University
Artsiom Antanovich Belarusian State University
L.D.A. Siebbeles ChemE/Opto-electronic Materials - AS
Mikhail Artemyev Belarusian State University
Ulrike Woggon Technical University of Berlin
Research Group
ChemE/Opto-electronic Materials (AS) (TU Delft)
Nanoplatelets Exciton binding energy Field-dependent PL Franz-Keldysh effect Quantum confined Stark effect
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Published Date

2016

Language

English

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Faculty

Applied Sciences

Department

ChemE/Chemical Engineering

Research Group

ChemE/Opto-electronic Materials

Abstract

We present a study of the application potential of CdSe nanoplatelets (NPLs), a model system for colloidal 2D materials, as field-controlled emitters. We demonstrate that their emission can be changed by 28% upon application of electrical fields up to 175 kV/cm, a very high modulation depth for field-controlled nanoemitters. From our experimental results we estimate the exciton binding energy in 5.5 monolayer CdSe nanoplatelets to be EB = 170 meV; hence CdSe NPLs exhibit highly robust excitons which are stable even at room temperature. This opens up the possibility to tune the emission and recombination dynamics efficiently by external fields. Our analysis further allows a quantitative discrimination of spectral changes of the emission energy and changes in PL intensity related to broadening of the emission line width as well as changes in the intrinsic radiative rates which are directly connected to the measured changes in the PL decay dynamics. With the developed field-dependent population model treating all occurring field-dependent effects in a global analysis, we are able to quantify, e.g., the ground state exciton transition dipole moment (3.0 × 10-29 Cm) and its polarizability, which determine the radiative rate, as well as the (static) exciton polarizability (8.6 × 10-8 eV cm2/kV2), all in good agreement with theory. Our results show that an efficient field control over the exciton recombination dynamics, emission line width, and emission energy in these nanoparticles is feasible and opens up application potential as field-controlled emitters.