Discovery of Type II Interlayer Trions

Abstract

In terms of interlayer trions, electronic excitations in van der Waals heterostructures (vdWHs) can be classified into Type I (i.e., two identical charges in the same layer) and Type II (i.e., two identical charges in the different layers). Type I interlayer trions are investigated theoretically and experimentally. By contrast, Type II interlayer trions remain elusive in vdWHs, due to inadequate free charges, unsuitable band alignment, reduced Coulomb interactions, poor interface quality, etc. Here, the first observation of Type II interlayer trions is reported by exploring band alignments and choosing an atomically thin organic–inorganic system—monolayer WSe2/bilayer pentacene heterostructure (1L + 2L HS). Both positive and negative Type II interlayer trions are electrically tuned and observed via PL spectroscopy. In particular, Type II interlayer trions exhibit in‐plane anisotropic emission, possibly caused by their unique spatial structure and anisotropic charge interactions, which is highly correlated with the transition dipole moment of pentacene. The results pave the way to develop excitonic devices and all‐optical circuits using atomically thin organic–inorganic bilayers.

Strong quenching of dye fluorescence in monomeric perylene orange/TMDC hybrid structures

“…Finally, the emission peak could be a sign of interlayer exciton formation, where the electron resides in the PO layer and the hole in the WSe 2 . 28,54,55 Summing up the m-PL measurements, we found a strong indication for uorescence intensity quenching as well as a relatively enhanced trion PL when combining PO with WSe 2 in a hybrid structure. Yet, we cannot distinguish unambiguously between charge and energy transfer as the dominant contribution to the uorescence quenching.…”

“…Finally, the emission peak could be a sign of interlayer exciton formation, where the electron resides in the PO layer and the hole in the WSe 2 . 28,54,55…”

A Droplet Method for Synthesis of Multiclass Ultrathin Metal Halides

“…At 80 K, the SbI 3 nanosheet exhibits a PL peak at 773 nm, while the monolayer WSe 2 possesses two distinct peaks that can be wellfitted by Gaussian curves (Figure 4c). [39] Clearly, the strong PL peak of monolayer WSe 2 appears at 722 nm and the weak peak at 733 nm, as corresponding to neutral exciton (X) and positive trion (T), [40][41][42] respectively. After covering with SbI 3 , the X emission of WSe 2 in SbI 3 /WSe 2 heterostructure reduces by 50%, while the trion emission significantly enhances by 230% (Figure 4d).…”

Progress and Insight of Van der Waals Heterostructures Containing Interlayer Transition for Near Infrared Photodetectors

“…It can adjust the band alignment of the materials that are responsible for tuning the interlayer charge coupling and induce the charge spatial separation as well as enhance the optical absorption. [20] Owing to the process of interlayer charge coupling in vdWs heterostructure, this mechanism can allow achieving broaden detection range by flouting the restriction of the bandgaps limitations of materials and thus improved the photocarrier separation by strong built-in potential and thus improved optical parameters such as R, D * , EQE, etc. [21] In photodetectors based on vdWs heterojunctions, optical photoresponse can rapidly be improved by enhancing several factors including fast interface such as tunneling, band alignment, and tunneling mechanism.…”