How Biexciton Systems interact in a Quantized Radiation Field

Frenkel excitons are quasiparticles that possess momentum, energy, and a center of mass. Excitons are the produces of electrons jumping up from the valence band of molecules to the conducting band. The exciton is the relationship between the excited electron and the hole. The electron-hole it leaves behind in the valence band. Biexcitons are two bound exciton systems and can be found in a broad range of matter from DNA to organic semiconductors and used as sophisticated probes for spectroscopy. Biexcitons have not been fully understood within organic solids and lattices, yet theoretical physics work states that it should be possible. This study sought to numerically quantify the interactions between the excitons in the biexciton system as this will pave new paths toward understanding the many-body electric structures that are in many molecular excitonic systems. Some examples of these systems are organic semiconductor crystals, molecular aggregates, DNA, and photosynthetic light-harvesting complexes. Quantum trajectory simulations, as well as theoretical quantum physics and organic chemistry, were used to explore biexciton behavior. Applying Schrödinger's equation to the matrix produced by these simulations, the probability of the exciton systems' location within an artificial box could be calculated. Results suggest that molecular geometries and the interaction energies between the two bound excitons govern the behaviors of biexcitons systems resulting in their stability within the organic solids. Additionally, the measurements reveal a set of microscopic criteria for the attractive or repulsive nature of biexciton binding in macromolecular semiconductors.