Engineering of the Exciton Binding Energies in 2D Metal Halide Perovskites*

2D metal halide perovskites (MHPs) are a class of materials that have recently gained traction in the material science community due to the tunability of their band gap (E_g) and exciton binding energies (E_b). However, these techniques have given varied and inconsistent results. Our research group used a technique called electroabsorption to accurately and precisely measure E_g and E_b in 31 different perovskites found in our published paper [Hansen et al., Matter 6, 3463-3482 (2023)]. By measuring these MHPs we have found that a superlattice of repeating wells and barriers describes the effect the inorganic dielectric constant (metal halide layer) has on E_b.