Terahertz-Field-Induced Dissociation of Frenkel Excitons in Organic Semiconductors

Excitons serve as the primary energy carriers for many organic semiconductor devices and chemical systems; however, understanding how these bound electron-hole pairs dissociate into free carriers on an ultrafast time scale remains challenging. Here, we demonstrate a contact-free approach using intense, single-cycle terahertz (THz) pulses to promote the dissociation of excitons via a field-induced charge hopping process. Applying this method to a prototypical organic semiconductor, we observe a photocurrent enhancement exceeding 100% under THz excitation. Time-resolved measurements reveal that hot excitons (formed immediately after above-bandgap photoexcitation) are particularly susceptible to dissociation. These findings establish a nonequilibrium, field-driven route for engineering exciton dissociation in a wide range of optoelectronic materials, providing a broadly applicable strategy to enhance photovoltaic performance as well as potential electrophotocatalytic applications through strong-field light-matter interactions.