Photoluminescence Enhancement in Thickness-Controlled PTCDA/MoS₂

Two-dimensional (2D) crystalline heterojunctions comprising organic and inorganic semiconductors represent an emerging platform for next-generation optoelectronics, yet their energy-level alignment and interfacial energy flow remain under active debate. At the PTCDA/MoS₂ interface, prior studies have reported both photoluminescence (PL) quenching and enhancement, likely arising from sample inhomogeneity. In this work, we grow 2D PTCDA crystals with controlled thickness on high-quality monolayer MoS₂ and investigate the interfacial energy flow. Upon PTCDA deposition, the MoS₂ PL increases markedly and reproducibly. This enhancement originates from two distinct mechanisms. First, static interfacial hole doping suppresses trion formation and restores radiative neutral-exciton emission. Second, a dynamic channel of exciton energy transfer delivers additional excitation from PTCDA to MoS₂. Together, these effects reconcile previously conflicting observations and establish a unified framework for engineering emission and light harvesting in organic-inorganic 2D heterostructures.