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Main Authors: Thériault, Pierre-Luc, Azek, Emna, Juteau, Gabriel, Mukherjee, Anagh, Humeniuk, Heorhii V., He, Zhechang, Malinge, Alexandre, Perepichka, Dmytro F., Simine, Lena, Kéna-Cohen, Stéphane
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2604.16692
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author Thériault, Pierre-Luc
Azek, Emna
Juteau, Gabriel
Mukherjee, Anagh
Humeniuk, Heorhii V.
He, Zhechang
Malinge, Alexandre
Perepichka, Dmytro F.
Simine, Lena
Kéna-Cohen, Stéphane
author_facet Thériault, Pierre-Luc
Azek, Emna
Juteau, Gabriel
Mukherjee, Anagh
Humeniuk, Heorhii V.
He, Zhechang
Malinge, Alexandre
Perepichka, Dmytro F.
Simine, Lena
Kéna-Cohen, Stéphane
contents The performance of organic optoelectronic devices is critically dependent on how molecules orient within organic thin films. Yet, standard characterization techniques only reveal the first and second moments of the molecular orientation distribution. This limitation obscures the true molecular arrangement, as diverse distributions can yield identical low-order averages while exhibiting distinct functional properties. Here, we bridge this gap by combining multi-harmonic nonlinear polarimetry (second, third, and fourth harmonic) with the Maximum Entropy Method to reconstruct the probability distribution without any \textit{a priori} assumptions. This allows us to resolve features in the distribution such as asymmetry and bimodality, that remain invisible to conventional probes. Furthermore, we use this method to benchmark molecular dynamics simulations, revealing that these simulations often fail to capture the complex distribution despite correctly predicting the first and second moments. This work transforms molecular orientation from an inferred average into a precise observable, establishing essential validation standards for predictive material design.
format Preprint
id arxiv_https___arxiv_org_abs_2604_16692
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Revealing full molecular orientation distributions in organic thin films by nonlinear polarimetry
Thériault, Pierre-Luc
Azek, Emna
Juteau, Gabriel
Mukherjee, Anagh
Humeniuk, Heorhii V.
He, Zhechang
Malinge, Alexandre
Perepichka, Dmytro F.
Simine, Lena
Kéna-Cohen, Stéphane
Optics
Materials Science
The performance of organic optoelectronic devices is critically dependent on how molecules orient within organic thin films. Yet, standard characterization techniques only reveal the first and second moments of the molecular orientation distribution. This limitation obscures the true molecular arrangement, as diverse distributions can yield identical low-order averages while exhibiting distinct functional properties. Here, we bridge this gap by combining multi-harmonic nonlinear polarimetry (second, third, and fourth harmonic) with the Maximum Entropy Method to reconstruct the probability distribution without any \textit{a priori} assumptions. This allows us to resolve features in the distribution such as asymmetry and bimodality, that remain invisible to conventional probes. Furthermore, we use this method to benchmark molecular dynamics simulations, revealing that these simulations often fail to capture the complex distribution despite correctly predicting the first and second moments. This work transforms molecular orientation from an inferred average into a precise observable, establishing essential validation standards for predictive material design.
title Revealing full molecular orientation distributions in organic thin films by nonlinear polarimetry
topic Optics
Materials Science
url https://arxiv.org/abs/2604.16692