Lattice Properties

The metal halide lattice with its strong ionic character which couples to the charge carriers plays a large role in dictating the optoelectronic properties of MHPs. 2D and 3D MHPs share some similarities but also exhibit strong differences in their lattice properties. The phonon structure is similar and both are dynamically active at room temperature, but in 3D MHPs the carriers exist as large polarons whereas the increase in exciton binding energy in 2D MHPs creates small polarons which couple to the lattice through a different interaction. This chapter explores what the literature says about those similarities and differences.