Universal Inverse Scaling of Exciton–Exciton Annihilation Coefficient with Exciton Lifetime

Be it for essential everyday applications such as bright light-emitting devices or to achieve Bose–Einstein condensation, materials in which high densities of excitons recombine radiatively are crucially important. However, in all excitonic materials, exciton–exciton annihilation (EEA) becomes the dominant loss mechanism at high densities. Typically, a macroscopic parameter named EEA coefficient (CEEA) is used to compare EEA rates between materials at the same density; higher CEEA implies higher EEA rate. Here, we find that the reported values of CEEA for 140 different materials is inversely related to the single-exciton lifetime. Since during EEA one exciton must relax to ground state, CEEA is proportional to the single-exciton recombination rate. This leads to the counterintuitive observation that the exciton density at which EEA starts to dominate is higher in a material with larger CEEA. These results broaden our understanding of EEA across different material systems and provide a vantage point for future excitonic materials and devices.