Significantly Increased Photoresponsivity of WSe₂‐Based Transistors through Hybridization with Gold‐Tetraphenylporphyrin as Efficient n‐Type Dopant

Abstract

The control of electrical and optical characteristics of 2D transition‐metal dichalcogenides (TMDCs) through charge doping is essential to optimize the performances of optoelectronic devices based on TMDCs. In this study, a few‐layer tungsten diselenide (WSe2) is hybridized with organic gold(III)‐tetraphenylporphyrin (Au‐TPP) using a simple drop‐casting method. Nanoscale optical characteristics, measured by laser confocal microscopy, reveal that the photoluminescence intensity and exciton lifetime of Au‐TPP decrease after the hybridization with WSe2, which suggests the charge transfer from Au‐TPP to WSe2. For optoelectronic applications, photoresponsive field‐effect transistors (FETs) based on pristine WSe2 and WSe2/Au‐TPP hybrids are fabricated and compared. After the hybridization with Au‐TPP, the charge transport characteristics of the WSe2‐based FETs change to severe n‐type characteristics including a negative shift of the threshold voltage and increase in electron mobility. Significantly enhanced photoresponsivities (up to 310 times) are observed for the WSe2/Au‐TPP‐based FETs owing to their efficient light absorption and charge transfer from Au‐TPP to WSe2.

Efficient and Air-Stable Doping of Folded MoS2 Nanosheets for Use in Field-Effect Transistors

“…Different concentrations of HAuCl 4 solution (0.1, 0.2, 0.5, and 1 mmol/L) were spin-coated on the samples, followed by annealing at 100 °C in N 2 for 90 s. Then, photolithography was repeated for thermal evaporation of Cr (5 nm)/Au (70 nm) electrodes (the channel length and width were 20 and 10 μm, respectively) (inset in Figure 4c). Figure S6 shows that as the dopant concentration increases, the electron density of MoS 2 gradually decreases, 21,25,40,41 and the folding structure accelerates the polarity conversion process, verifying that HAuCl 4 treatment is more efficient for the folded structure than for the intrinsic structure. At a HAuCl 4 solution concentration of 0.5 mmol/L, folded bilayer MoS 2 has completed the transition from an n-type to a p-type semiconductor, whereas intrinsic bilayer MoS 2 still exhibits bipolarity (Figures 4b and S5).…”

“…In addition to changing the electronic structure of MoS 2 , HAuCl 4 treatment also gradually changes the polarity of MoS 2 . , The electrical properties of MoS 2 were directly measured by fabricating FETs (Figure a). To prevent current leakage by Au III ions, a doping area was designated via photolithography, and other areas were protected by a photoresist.…”

Charge-Transfer Effect and Enhanced Photoresponsivity of WS2- and MoSe2-Based Field Effect Transistors with π-Conjugated Polyelectrolyte

“…The TR-PL spectra were obtained using a time-correlated single-photon counting system. The LCM PL and TR-PL spectroscopy methods were reported in detail in previous works. , The optical absorption spectra of pristine and FPS-K-treated MoSe 2 and WS 2 samples were measured using an Agilent 8453 UV–vis spectrophotometer. The binding energies of the constituent atoms of the samples were measured using X-ray photoelectron spectroscopy (XPS; Nexsa).…”

Self-Powered Bidirectional Photoresponse in High-Detectivity WSe2 Phototransistor with Asymmetrical van der Waals Stacking for Retinal Neurons Emulation

“…In the artificial retina system, optoelectronic sensors, which can emulate the neuron behaviors in the retina, are indispensable for visible information acquisition. In the past few decades, diverse optoelectronic sensors have been designed for artificial retina systems. − Most of them were based on 2D (two-dimensional) materials because 2D materials are capable of perceiving optical information and converting it into electrical signals for transmission and processing. , Among various 2D materials, tungsten diselenide (WSe 2 ) is drawing increasing attention not only because of its excellent optoelectronic properties but also because of its ambipolar nature. − Recently, WSe 2 -based optoelectronic devices, such as photodiodes, − phototransistors, − and optical memories, , have been demonstrated. Meanwhile, emerging WSe 2 -based devices for artificial retina systems have been proposed, as well …”