Exciton Transfer at Heterointerfaces of MoS₂ Monolayers and Fluorescent Molecular Aggregates

Abstract

Integration of distinct materials to form heterostructures enables the proposal of new functional devices based on emergent physical phenomena beyond the properties of the constituent materials. The optical responses and electrical transport characteristics of heterostructures depend on the charge and exciton transfer (CT and ET) at the interfaces, determined by the interfacial energy level alignment. In this work, heterostructures consisting of aggregates of fluorescent molecules (DY1) and 2D semiconductor MoS 2 monolayers are fabricated. Photoluminescence spectra of DY1/MoS 2 show quenching of the DY1 emission and enhancement of the MoS 2 emission, indicating a strong electronic interaction between these two materials. Nanoscopic mappings of the light‐induced contact potential difference changes rule out the CT process at the interface. Using femtosecond transient absorption spectroscopy, the rapid interfacial ET process from DY1 aggregates to MoS 2 and a fourfold extension of the exciton lifetime in MoS 2 are elucidated. These results suggest that the integration of 2D inorganic semiconductors with fluorescent molecules can provide versatile approaches to engineer the physical characteristics of materials for both fundamental studies and novel optoelectronic device applications.

Study on interface engineering and chemical bonding of the ReS2@ZnO heterointerface for efficient charge transfer and nonlinear optical conversion efficiency

“…This is in line with the strong RSA caused by electron transfer from ZnO to V Re -ReS 2 of DL mentioned earlier. 14 In addition, the Re vacancy causes the formation of DL, which can lead to more efficient interfacial CT, so the formation of the Zn–S bond is once again proven. 50…”

“…This may be attributed to exciton transfer via band filling. 14 Carrier lifetimes of V Re -ReS 2 and V Re -ReS 2 @ZnO were fitted using double exponential functions, as shown in Table S1 (ESI †). Carrier lifetime of V Re -ReS 2 : t 1 = 1.89 ps, t 2 = 2.6 ps, t 3 = 2.2 Â 10 3 ps.…”

“…1(b). S. Kwon et al 14 successfully prepared a type I heterostructure of fluorescent molecules (DY1)/MoS 2 . It was demonstrated that the transfer of photogenerated excitons from a fluorescent DY1 to monolayer MoS 2 enhanced the PL luminescence of MoS 2 .…”

van der Waals 2D transition metal dichalcogenide/organic hybridized heterostructures: recent breakthroughs and emerging prospects of the device

“…Minimal changes in the light-induced contact potential difference (CPD) at the DY1/MoS 2 interface eliminated the possibility of an interlayer charge transfer process, confirming the formation of a type-I heterojunction. 30 Again, it is found that while the excited-state electron transfer rate from TMDs (MoS 2 and WSe 2 ) to fullerenes (C 60 ) is relatively insensitive due to the band offset (more details discussed earlier), the electron transfer (ET) rate from TMDs to PTCDA is reduced by an order of magnitude when the band offset is quite large. 140 For the perylene crystal, the sensitivity of the electron transfer rate on the band offset is elucidated by the 1D nature of the electronic wave function, which limits the availability of states with the appropriate energy to accept the electron.…”

“…This observation points to a robust electronic interaction between these two materials. 30 In type II, in particular p–n junction, TMDO heterostructures, generally the PL emission peak quenches for individual layers; however, recently an extra ILX emission peak from the NIR to IR range has been observed. Due to their spatially indirect nature, interlayer excitons possess long-lifetimes, attributed to the reduced overlap between electron and hole wavefunctions, 31,32 extended spatial coherence of the excitons, 33 quantum emitter, 34 and high-temperature exciton condensate.…”