Singlet Exciton Dynamics of Perylene Diimide- and Tetracene-Based Hetero/Homogeneous Substrates via an Ab Initio Kinetic Monte Carlo Model

Luminescent solar concentrators (LSCs) are devices that trap a portion of the solar spectrum and funnel it toward photon-harvesting devices. The modeling of LSCs at a quantum chemical level, however, remains a challenge due to the complexity of exciton and photon dynamic modeling. 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. Ab initio rate constants are computed using time-dependent density functional theory-based methods. PDI-type substrates are observed to display enhanced singlet exciton transport properties compared to tetracene. Simulations show that substrates with dipole-aligned chromophores are characterized 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 multidopant substrate, transport is predominantly mediated by PDI due to the asymmetry in the transport rates between the two dyes considered. We conclude by discussing the properties of multidopant substrates and how they can impact the design of next-generation LSCs.