2D TiS₂ Layers: A Superior Nonlinear Optical Limiting Material

Abstract

not limited to solar energy harvesting, thin film transistors, light emitting diodes, sensors, optical limiters, and wearable devices. [1] Materials with enhanced optical limiting properties are of great demand in protecting various optical devices from laser radiations. A good optical limiter is a material which allows the optical radiation to pass through at low fluences but clamps the transmitted intensity as the incident laser fluence increases. This property of materials can be useful to fabricate devices for pulse shaping, [2] passive mode locking, [3] and eye protection against powerful lasers. [4] Typically, optical limiting happens in materials is due to reverse saturable absorption or excited state absorption. When a material is illuminated with a laser beam, it can absorb the laser light even when the incident laser energy is lower than the band gap of the material by two-photon absorption (2PA). However, in a direct band gap material in which the incident laser energy is higher than the band gap, the appreciable linear absorption induces free carrier absorption. [5] In the bulk form, most of the 2D dichalcogenides are indirect-band gap materials with conduction band minimum and valence band maximum located at Q and Γ points, respectively. [6] In the monolayer regime, the dichalcogenides The advancement in high power lasers has urged the requisite of efficient optical limiting materials for both eye and sensor protection. The discovery of atomically thin 2D transition metal dichacogenides with distinctive properties has paved the way for a variety of applications including optical limiting. Until recently, the optical limiting effect exhibited by 2D materials is inferior to the benchmark materials fullerene (C 60 ) and graphene. This article reports the optical limiting activity of the 2D transition metal dichal cogenide, titanium disulfide (TiS 2 ) nanosheets, using optical and photo acoustic zscan techniques. The 77% nonlinear optical limiting exhibited by the TiS 2 sheets with 73% lineartransmittance is superior to that of any other existing 2D dichalcogenide sheets, graphene, and the benchmark optical limiting material, C 60 . The enhanced nonlinear response is attributed to the concerted effect of 2photon and the induced excited state absorp tions. By using photoacoustic zscan, a unique tool developed to determine the nonlinear optical limiting mechanism in materials, it is found that the optical limiting exhibited by TiS 2 2D sheets and graphene are mainly due to nonlinear absorption rather than scattering effects. These results have opened the door for 2Ddichalcogenidematerialsbased highly efficient optical limiters, especially at low fluences.Since the advent of graphene, 2D materials have gained considerable attention owing to their incredible electrical and optical properties. Current efforts to utilize the unique features of these materials have been focused on their integration into a vast array of electrooptical applications. These include but are [+] Present address:

Structural transformation and room temperature ammonia sensing properties of TiS2 nanostructures

“…The diffraction pattern for bulk sample matches well with hexagonal TiS 2 (JCPDS-74 1141; space group p3m1, a = 3.39 Å, c = 5.69 Å). The XRD from a bulk crystalline TiS 2 powder displays a sharp intense peak corresponding to (001) planes, implying preferred c-axis orientation [31,32]. Further, we note that after exfoliation, relative intensity of most of the planes as compared with (001) plane has reduced and hence the exfoliated thin sheets of TiS 2 exhibit c-axis orientation.…”

2D Group IVB Transition Metal Dichalcogenides

“…Although TMDs such as MoS 2 , WS 2 , and ReS 2 exhibit great performance in the field of photodetectors, more in‐depth explorations on the optoelectronic applications of TMD family are still necessary . 2D Group IVB TMDs as great potential materials for photodetection applications have demonstrated some excellent photodetection properties, such as an extremely high responsivity, external quantum efficiency, and fast photoresponse.…”

Solvent exfoliation stabilizes TiS2 nanosheets against oxidation, facilitating lithium storage applications

“…For example, titanium disulfide is a less-celebrated member of the TMD family. Although it has recently been utilized in applications including non-linear optical devices 16 and thermoelec-trics 17 and has long been proposed as a lithium ion storage material, [18][19][20][21] TiS 2 suffers from a significant disadvantage: its low oxidative stability under ambient conditions. 22,23 As a result, this promising material has not yet reached its full potential.…”