Singlet exciton dynamics of perylene diimide and tetracene based hetero/homogeneous substrates via an \textit{ab initio} kinetic Monte Carlo model

TL;DR

This paper models singlet exciton dynamics in luminescent solar concentrators using an ab initio kinetic Monte Carlo approach, revealing how substrate composition and chromophore alignment influence exciton transport.

Contribution

It introduces an ab initio kinetic Monte Carlo model to predict exciton transport properties in LSC substrates, highlighting the effects of chromophore type and alignment.

Findings

PDI substrates show enhanced exciton transport compared to tetracene.

Dipole alignment causes anisotropic exciton diffusion with improved transport.

Multi-dopant substrates favor PDI-mediated exciton transport.

Abstract

Luminescent solar concentrators (LSCs) are devices that trap a portion of the solar spectrum and funnel it towards photon harvesting devices. The modelling of LSCs at a quantum chemical level however, remains a challenge due to the complexity of exciton and photon dynamic modelling. This study examines singlet exciton dynamics occurring within a typical LSC device. To do this, we use a rejection-free kinetic Monte Carlo method to predict diffusion lengths, diffusion coefficients, substrate anisotropy, and average exciton lifetimes of perylene diimide (PDI) and tetracene based substrates in the low concentration scheme. \textit{Ab initio} rate constants are computed using time-dependant density functional theory based methods. PDI type substrates are observed to display enhanced singlet exciton transport properties when compared to tetracene. Simulations show that substrates with dipole-aligned chromophores are characterised by anisotropic exciton diffusion, with slightly improved transport properties. Finally, a PDI-tetracene substrate is simulated for both disordered and dipole-aligned chromophore configurations. In this multi-dopant substrate transport is predominantly mediated by PDI due to the asymmetry in the transport rates between the two dyes considered. We conclude discussing the properties of multi-dopant substrates and how they can impact the design of next generation LSCs.