Fast Photoresponse from Hybrid Monolayer MoS₂/Organic Photodetector

Abstract

As a direct‐bandgap transition semiconductor with high carrier mobility, monolayer (ML) transition metal dichalcogenides (TMDCs) have attracted significant attention as a promising class of material for photodetection. It is reported that these layers exhibit a persistent photoconductance (PPC) effect, which is assigned to long‐lasting hole capture by deep traps. Therefore, TMDCs‐based photodetectors show a high photoresponse but also a slow response. Herein, intensity‐modulated photocurrent spectroscopy (IMPS) with steady‐state background illumination is performed to investigate the photoresponse dynamics in a hybrid photodetector based on ML MoS2 covered with an ultrathin layer of phthalocyanine (H2Pc) molecules. The results demonstrate that adding the H2Pc layer speeds up the photoresponse of the neat ML‐MoS2 photodetector by almost two orders of magnitude without deteriorating its responsivity. The origin of these improvements is revealed by applying the Hornbeck–Haynes model to the photocarrier dynamics in the IMPS experiment. It is shown that the improved response speed of the hybrid device arises mostly from a faster detrapping of holes in the presence of the H2Pc layer, while the trap densities remain rather unchanged. Meanwhile, the additional absorption of photons in the H2Pc layer contributes to photocarrier generation, resulting in an enlarged responsivity of the hybrid device.

High‐Performance Air‐Stable 2D‐WSe2/P3HT Based Inorganic–Organic Hybrid Photodetector with Broadband Visible to Near‐IR Light Detection

“…The fast photoresponse speed observed in the current device is a result of the faster detrapping of holes in the presence of the organic layer. [ 39 ] Since the fermi level is close to the conduction band in n‐type WSe 2 , most of the electron traps will be hence filled and can be neglected. It is, therefore, that the response time of the device will depend on the hole trapping and detrapping lifetimes.…”

Solution-Processed Functionalized MoS2 Nanosheets Composite for Photodetection Application

“…A single-layer MoS 2 nanosheet forms a hexagonal lattice structure and contains three sublayers of atoms, where one layer of Mo atoms is sandwiched between two layers of S atoms. Most photodetector studies [6][7][8][9][10][11][12][13][14][15][16][17] use single-layered and multilayered individual nanosheets, though positive results with multilayered nanosheet composites in the sandwich structure were shown [18]. Single-layered nanosheets synthesized by CVD are widely known to be very time and energy-consuming and, therefore, expensive.…”

“…Unfortunately, the characteristics of these photodetectors are insufficiently high because of a lower ordering degree than the one in independent single nanosheets, as well as the presence of contacts between the nanosheets, resulting in lower conductivity. To achieve good performance of photodetectors (high responsibility, short response time, and high detectivity), both the physical and chemical functionalization of such nanosheets are widely utilized [3,[13][14][15][16][17]20,21]. Many inorganic [1,3,12] and organic [3,8,9,[13][14][15][16][17]20,21] nanomaterials have been used for functionalization.…”

“…To achieve good performance of photodetectors (high responsibility, short response time, and high detectivity), both the physical and chemical functionalization of such nanosheets are widely utilized [3,[13][14][15][16][17]20,21]. Many inorganic [1,3,12] and organic [3,8,9,[13][14][15][16][17]20,21] nanomaterials have been used for functionalization. Most of the studies are devoted to physical functionalization [14][15][16][17]21].…”

“…Many inorganic [1,3,12] and organic [3,8,9,[13][14][15][16][17]20,21] nanomaterials have been used for functionalization. Most of the studies are devoted to physical functionalization [14][15][16][17]21]. However, chemical functionalization can provide more stable materials as it is irreversible.…”