Layer‐To‐Layer Direct Recombination in Organic Planar p/n Heterojunctions

Organic planar pn heterojunctions demonstrate distinct optoelectronic properties governed by organic-organic interface interactions, while the fundamental recombination mechanisms lack a comprehensive understanding. Herein, we derive a recombination model applicable to planar p-n heterojunction systems through implementation of the Miller-Abrahams (MA) hopping theory. Integrating the model into self-consistent 1D drift-diffusion simulations yields temperature-dependent current density-voltage characteristics that reproduce experimental trends, validating its predictive capability. This model demonstrates that enhancing hopping frequency and strengthening delocalization between molecules are critical for optimizing recombination efficiency, thus providing an effective approach for performance improvement. The developed model is broadly applicable to planar p-n heterojunction systems, enabling quantitative assessment of intermolecular interaction strength between two distinct molecules.