Ultrasensitive Photodetectors Promoted by Interfacial Charge Transfer from Layered Perovskites to Chemical Vapor Deposition‐Grown MoS₂

Abstract

Heterostructures for charge‐carrier manipulation have laid the foundation of modern optoelectronic devices, such as photovoltaics and photodetectors. High‐performance heterostructure devices usually impose stringent requirements on the material quality to sustain efficient carrier transport and charge transfer, thus leading to sophisticated fabrication processes. Here, a simple yet efficient strategy is proposed to develop ultrasensitive photodetectors based on heterostructures of chemical vapor deposition‐grown MoS2 and polycrystalline‐layered perovskites. The layered perovskites possess pure crystallographic orientation with conductive edges in contact with MoS2, which gives rise to efficient light absorption, exciton diffusion, and interfacial charge transfer. In dark state, the mismatch of work functions of two materials facilitates low dark currents by the depletion of electrons in MoS2. Under light irradiation, efficient exciton diffusion and interfacial charge transfer are realized in the heterostructures with type‐II band alignment, which produces drifting electrons in MoS2 and leaves trapped holes in layered perovskites. The photodetectors present suppress noises and boost photocurrents, yielding a champion device with a responsivity of 2.5 × 104 A W−1, and a specific detectivity of 4.1 × 1014 Jones. The results demonstrate a scalable approach for the integration of high‐performance devices with high tolerance to defects.

Pattern-Selective Molecular Epitaxial Growth of Single-Crystalline Perovskite Arrays toward Ultrasensitive and Ultrafast Photodetector

“…The high sensitivity requires high-electrical-resistance materials to suppress dark current, whereas the fast responsivity demands high photoconductive carriers. 37 The photoconductive gain (G) is defined by G = τη/ τ tr , where τ and τ tr are the carrier lifetime and transit time, respectively. η is the external quantum yield, which is proportional to the absorption of active layers.…”

“…The high sensitivity and fast responsivity of photodetectors are conventionally contradictory. The high sensitivity requires high-electrical-resistance materials to suppress dark current, whereas the fast responsivity demands high photoconductive carriers . The photoconductive gain ( G ) is defined by G = τη / τ tr , where τ and τ tr are the carrier lifetime and transit time, respectively.…”

Layer-by-Layer Growth of AA-Stacking MoS2 for Tunable Broadband Phototransistors

“…Molybdenum disulfide (MoS 2 ) as the typical member of two-dimensional (2D) transition metal dichalcogenides (TMDCs) has attracted tremendous attention due to its rich physical/chemical properties, such as layer-dependent electronic structure, layer-dependent photoexcitation, high mobility, and reasonable band gap. − Different than other 2D TMDCs, MoS 2 is earth-abundant and environmentally stable. Thus, it has been considered as a promising candidate for post-Moore’s law era. − The recent development, such as construct MoS 2 transistors with 1 nm channel, MoS 2 circuits, and MoS 2 room photodetectors with detection range from visible to near-infrared, exhibits its potentials in novel applications like electronic and optoelectronic devices. ,− Although the monolayer MoS 2 has gained more investigation, more and more research demonstrated that the device based on few-layer MoS 2 has a higher device carrier mobility caused by the lower contact resistance, which is one of the most important factors when evaluating the semiconductor devices. − Besides the thickness factor, the electrical property of few-layer MoS 2 is also related to its stacking orientation, where the AA-stacking bilayer MoS 2 has a higher carrier mobility than that of AB-stacking bilayer MoS 2 , and the 30°-twisted bilayer MoS 2 has a higher electrical property than its 0°-twisted bilayer MoS 2 . Thus, the controlling growth of MoS 2 including the thickness and stacking orientation has attracted more and more attention.…”

Engineering sensitivity and spectral range of photodetection in van der Waals materials and hybrids

“…Upon irradiation, electron transfer occurs from perovskite layer edges to MoS 2 while the holes are trapped in the perovskite crystallites. The fabrication procedure is simple and involves spin-coating the perovskite layer on the CVD grown MoS 2 [140]. Other 2D analogues like InSe [9,141,142], and Bi 2 Se 3 [143] also show a similar trend, and their spectral bandwidth is much larger, extending into the NIR region.…”