From Island to Island: How Energy Travels in a Fragmented Crystal

From Island to Island: How Energy Travels in a Fragmented Crystal - Featured

This study reports a new class of two-dimensional lead-bromide perovskite based on monovalent 4-aminomethylbenzoic acid (AMBA) cations featuring a discontinuous inorganic layer. Strong hydrogen-bonding interactions at the interlayer between AMBA molecules impose structural rigidity that prevents the formation of continuous metal-halide layers, instead generating isolated linear islands of three edge-sharing [PbBr_6]^4− octahedra (Pb_3Br_14). The anisotropic in-plane arrangement of the structure is confirmed by angle-resolved polarized Raman spectroscopy, which reveals directional vibrational modes aligned with the octahedral island orientation. Despite the discontinuous lattice, transient photoluminescence microscopy demonstrates efficient in-plane exciton transport. Transport is strongly anisotropic, with the diffusion coefficient along the c-axis (0.149 cm^2/s) exceeding that along the a-axis (0.042 cm^2/s) by over threefold. This anisotropy is attributed to preferential near-field resonant energy transfer between the anisotropically oriented islands, as confirmed by numerical simulations, offering an efficient alternative transport mechanism in discontinuous layered perovskites. [Full Article]