# Computational Strategies for Predicting Excited‐State Energies in Eu3+ Down‐Shifting Spectral Converters for Photovoltaic Devices

## TL;DR

This paper introduces a computational method to predict the energy levels of europium-based compounds for use in solar cells.

## Contribution

The novel contribution is a low-cost computational protocol using DFT and TD-DFT to predict excited-state energies in Eu3+ complexes.

## Key findings

- The model accurately replicates experimental data for known compounds.
- It successfully predicts triplet-state energies for new compounds not in the training set.
- The approach aims to assess the potential of lanthanide complexes as down-shifting spectral converters in solar cells.

## Abstract

In this work, a computational protocol has been developed to predict the ligand‐based low‐lying excited‐state energies of Eu3+ coordination compounds with antenna ligands. A computational strategy, based on density functional theory (DFT) and time‐dependent density functional theory (TD‐DFT), has been developed using compounds with reliable structural and spectroscopic experimental data as a reference set. This approach aims to predict both the geometry and energy of the lowest‐excited triplet state, critical factors influencing the efficiency of the antenna effect and energy transfer to the Eu3+ ion. The model not only shows the ability to replicate available experimental data at a relatively low computational cost, but also accurately predicts triplet‐state energies for compounds that have not been included in the training set. This work is a first step toward the development of an affordable method for accurate predictions of the quantum yield of lanthanide‐based complexes to assess their potential application as down‐shifting spectral converters in solar cells.

A computational strategy to compute the energy of the triplet excited state in europium‐based coordination complexes is presented. This method allows for in silico screening of new systems with can be used as photosensitizers in solar cell‐based technologies.© 2026 WILEY‐VCH GmbH