Hybrid Heterostructures to Generate Long-Lived and Mobile Photocarriers in Graphene

Abstract

We report the generation of long-lived and highly mobile photocarriers in hybrid van der Waals heterostructures that are formed by monolayer graphene, few-layer transition metal dichalcogenides, and the organic semiconductor F8ZnPc. Samples are fabricated by dry transfer of mechanically exfoliated MoS2 or WS2 few-layer flakes on a graphene film, followed by deposition of F8ZnPc. Transient absorption microscopy measurements are performed to study the photocarrier dynamics. In heterostructures of F8ZnPc/few-layer-MoS2/graphene, electrons excited in F8ZnPc can transfer to graphene and thus be separated from the holes that reside in F8ZnPc. By increasing the thickness of MoS2, these electrons acquire long recombination lifetimes of over 100 ps and a high mobility of 2800 cm2 V–1 s–1. Graphene doping with mobile holes is also demonstrated with WS2 as the middle layers. These artificial heterostructures can improve the performance of graphene-based optoelectronic devices.

Enthalpy-uphill exciton dissociation in organic/2D heterostructures promotes free carrier generation

“…Our previous optical spectroscopy work has shown that this heterostructure can generate separated electrons and holes effectively. 32 The detailed sample preparation procedure can be found in the Sample preparation section. Before the deposition, the ML-WS 2 was annealed at 400–450 °C for ∼30 hours, which was then characterized in situ by angle-resolved photoemission spectroscopy (ARPES).…”

“…Although observations of free carrier generation from similar interfaces have been reported in several previous works, [32][33][34][35] these works have not resolved whether the CS state has a higher energy than the CT excitons. Indeed, many earlier studies on organic interfaces have suggested that effective CS relies on the extraction of electrons from CT excitons via some lower energy sites originating from interfacial mixing 36,37 or disorders.…”

Characteristics and Applicability Analysis of Nanomorphological Structures for Chemosensors: A Systematic Review

“…Graphene-related research includes optoelectronic devices, electrochemical transparency, electronic properties, Raman radiation patterns, piezoelectric nanogenerators, mobile photocarriers, etc. [59][60][61][62][63][64]. Wen Chen et al explained that graphene films are widely applied in supercapacitors due to their high electrical conductivity and excellent mechanical strength.…”

Nanoscale Periodic Trapping Sites for Interlayer Excitons Built by Deformable Molecular Crystal on 2D Crystal

“…45 Hybrid heterostructures can be used to generate long-lived and mobile photocarriers in graphene. 46 IX properties at hybrid molecule/TMDC interfaces are often investigated as a function of the interfacial band alignment and band bending. The variation in the electronic potential in directions parallel to the interface (the in-plane direction) is often neglected.…”

“…The very long triplet lifetime of organic molecules can also be used to enhance the photoluminescence intensity in TMDC through triplet energy transfer . Hybrid heterostructures can be used to generate long-lived and mobile photocarriers in graphene …”