Bandgap Renormalization in Monolayer MoS₂ on CsPbBr₃ Quantum Dots via Charge Transfer at Room Temperature

Abstract

Many‐body effect and strong Coulomb interaction in monolayer transition metal dichalcogenides lead to intrinsic bandgap shrinking, originating from the renormalization of electrical/optical bandgap, exciton binding energy, and spin‐orbit splitting. This renormalization phenomenon has been commonly observed at low temperature and requires high photon excitation density. Here, the augmented bandgap renormalization (BGR) in monolayer MoS2 anchored on CsPbBr3 perovskite quantum dots at room temperature via charge transfer is presented. The amount of electrons significantly transferred from perovskite gives rise to the large plasma screening in MoS2. The bandgap in heterostructure is red‐shifted by 84 meV with minimal pump fluence, the highest BGR in monolayer MoS2 at room temperature, which saturates with a further increase of pump fluence. Further, it is found that the magnitude of BGR inversely relates to Thomas–Fermi screening length. This provides plenty of room to explore the BGR within existing vast libraries of large bandgap van der Waals heterostructure toward practical devices such as solar cells, photodetectors, and light‐emitting‐diodes.

Identifying Defect-Induced Trion in Monolayer WS2 via Carrier Screening Engineering

“…The consequence of PL energy with excitation intensity is the direct observation of the carrier screening effect. 32 In the WS 2 /SiO 2 sample, the A 0 peak remained moderately flat in region I and slightly blue-shifted in region II (Figure 4a), originating from the band-filling effect. 10,29,33 Similar results were observed in the Re-WS 2 /SiO 2 sample (Figure 4b), where the A 0 peak increases with elevating excitation intensity in region II due to the band filling.…”

Exciton Transfer at Heterointerfaces of MoS2 Monolayers and Fluorescent Molecular Aggregates

“…Moreover, the A exciton peak of DY1/MoS 2 exhibits a blueshift of 20 meV compared to that of pristine MoS 2 , as marked by the blue arrow in Figure 4b , which indicates an increase in neutral excitons in MoS 2 . [ 37 ] With 2.76 eV (450 nm) of the excitation photon energy, free carriers can be generated in MoS 2 . The free carriers in MoS 2 form neutral excitons (A 0 ) and trions (A – ), of which TA signals are located near the energy around 1.9 eV (650 nm) and below, respectively.…”

Size-Dependent Mutual Charge Transfer between B- and P-Codoped Si Quantum Dots and Monolayer MoS2

“…Under photoexcitation, excited holes are preferentially transferred to Si QDs, while excited electrons remain in 1L-MoS 2 . This charge separation makes 1L-MoS 2 more heavily n-type-doped (photodoping), ,, which appears as the strong quenching of A exciton emission by Si QD deposition. Under strong excitation, the band gap of 1L-MoS 2 is reduced by the band gap renormalization. , However, the situation is identical to the case of weak excitation and, thus, no discontinuity is observed in the excitation power dependence of the A exciton emission (Figure f).…”

“…The PL peak is around 1.89 eV. This indicates that the PL spectrum is dominated by the A exciton emission. ,, …”