Third-order photon correlations to extract single nanocrystal multiexciton properties in solution
Data files
Dec 04, 2024 version files 74.66 GB
Apr 08, 2025 version files 51.45 GB
Jul 08, 2025 version files 51.45 GB
Abstract
Colloidal semiconductor nanocrystals are considered promising materials for high-flux optical
applications including lasing, light-emitting diodes, biological imaging, and quantum optics. In
high-flux applications, multiexcitons can significantly contribute to emission, influencing its
brightness, spectral purity, and kinetics. As a result, understanding and controlling multiexciton
emission in colloidal nanocrystal materials is of the utmost importance. In the past, single
nanocrystal photon correlation methods have been applied to understand biexciton and
triexciton efficiencies, lifetimes, and spectra. While powerful, such methods suffer from user
selection bias and require stable emission from single nanocrystals. To compensate for this
shortcoming, second-order correlation methods were developed to extract sample-averaged
biexciton properties from a solution of nanocrystals. Until now, however, the analogous third
order solution photon correlation methods remained unexplored. In this work, we present a pair
of third-order photon correlation techniques to obtain the sample-averaged single nanocrystal
triexciton quantum yield and lifetime in a solution-phase experiment. These techniques derive
from the relationship between the Poisson probability of nanocrystal photon absorption and the
intrinsic probability of nanocrystal photon emission. We validate the theoretical background of
these techniques by creating a numerical model to simulate the diffusion and emission of many
nanocrystals in solution. Our simulations confirm that the average triexciton quantum yield and
triexciton lifetime can be extracted from a solution of nanocrystals. These techniques will
enable researchers to gain a better understanding of the fundamental multiexciton properties of
colloidal nanocrystals.
https://doi.org/10.5061/dryad.2547d7x1z
Description of the data and file structure
Files are stored in matlab (.mat) format
Folder/File Naming
There are two naming structures: One for the solution triexciton quantum yield data and the other for the solution triexciton lifetime data.
Solution Triexciton Quantum Yield Data
For the solution triexciton quantum yield data, the data is stored in folders with the naming convention 'Photons_jBX_iTX' where j and i correspond to the simulated biexciton and triexciton quantum yield, respectively.
Within each folder, the photon stream is split up into a series of photon stream batches which are named 'Photons_1', 'Photons_2','Photons_3',etc.
Solution Triexciton Lifetime Data
For the solution triexciton lifetime data, the data is stored in folders with the naming convention 'Photons_7p5BX_iTX' where i corresponds to the simulated triexciton lifetime.
Within each folder, the photon is split up by each individual nanocrystal photon stream which are named 'qd_1', 'qd_2',' qd_3', etc.
File Content
Solution Triexciton Quantum Yield Data
Each 'Photons_i' file contains three one-dimensional matlab arrays corresponding to the Channel A, Channel B, and Channel C photon streams to be correlated. The photon stream data is in units of picoseconds. We recommend that the third-order cross-correlations are performed on each photon stream batch individually, and then sum the third-order cross-correlations of each batch at the end.
Solution Triexciton Lifetime Data
Each 'qd_i' file contains one two-dimensional matlab array. The first column corresponds to the detection time of the event (in seconds) and the second column corresponds to the detector the event occurred at (0 = excitation time, 1 = Channel A, 2 = Channel B, 3 = Channel C, 4 = Channel D'). We recommend each 'qd_i' file is combined into one large photon stream to perform the Photon Number Resolved Analysis. Below is a sample code that concatenates all the NC photon streams:
function [chT] = ConcatenatePhotonStream(folderName)
% determine number of files in the folder
numNC = length(dir([[folderName], '/*.mat']));
% initialize the concatenated photon stream array
chT = [];
for ii = 1:numNC
% load in the single NC photon stream
photons = load([folderName '/qd_' num2str(ii) '.mat']).photons;
% add the NC photon stream to the end of the total photon stream array
chT = [chT;photons];
disp([num2str(ii) ' out of ' num2str(num_particles)])
end
% sort the photon stream in time order
chT = sortrows(chT);
% convert the photon stream time from seconds to picoseconds
chT(:,1) = chT(:,1)*1e12;
end
Update #1 (04/08/2025):
Third-order cross-correlation data was re-uploaded upon discovering a minor error in the third-order cross-correlation analysis algorithm that introduced a scaling factor to the data.
Update #2 (07/08/2025):
Updated the manuscript link now that the manuscript is accepted.