Defect healing and Förster resonant energy transfer in H2Pc-TMD organic-inorganic heterostructures

Mandić, Šimun; Senkić, Ana; Vujičić, Nataša

Abstract

Organic - inorganic heterostructures (HS) combine the strong light absorption and exciton generation capabilities of organic molecules with the unique excitonic properties of layered transition metal dichalcogenides (TMDs), where the interfacial band alignment dictates the optical response. In this work, we investigate the influence of H2Pc molecules on CVD-grown MoS2 and WS2 monolayers using correlative microscopy techniques - Kelvin probe force microscopy (KPFM), photoluminescence (PL), and Raman spectroscopy. Comprehensive analysis of both electronic and optical properties provides detailed insights into the energy band alignment in these two HS. Despite their similar band alignments, the heterostructures exhibit strikingly different optical signatures. In the case of H2Pc/MoS2 HS, the effect of defect healing is more pronounced, while for the H2Pc/WS2 HS, strong indications of Förster energy transfer are observed. These findings highlight the critical role of transition dipole moment in addition to spectral overlap between donor emission and acceptor absorption in the design of optoelectronic devices.