MoS 2 nanostructures as transparent material: Optical transmittance measurements P.S. Sachidanand a , M.M. Sreelal b , S. Reshmi b , Gauthami Viswan a , Manu Mohan b , Surya Kumar Gautam b , Rakesh Kumar Singh b,c , K. Bhattacharjee b,⇑ a Amrita Vishwa Vidyapeetham, Kollam, Kerala 690525, India b Indian Institute of Space Science and Technology, Thiruvananthapuram, Kerala 695547, India c Indian Institute of Technology (BHU), Varanasi, Uttar Pradesh 221005, India article info Article history: Received 14 March 2019 Received in revised form 11 May 2019 Accepted 12 May 2019 Available online xxxx Keywords: Transition metal dichalcogenides (TMDs) Optical microscopy Optical transmittance Optical imaging Image processing abstract Optical transmittance measurements of MoS 2 nanostructures with varying film thickness are reported here. Optical transmittance value of the films containing assorted MoS 2 nanostructures (revealed by SEM studies) was obtained from optical microscope images taken under white light with 100 magnifi- cation and also from the images acquired under an ordinary lens-laser combination. The relationship between the light exposed on the sample and the pixel intensities of the images are being exploited to establish a correspondence between average pixel intensity and the transmittance obtained by numerical coding. Our measurements show a transmittance variation in the range of 0.92–0.68 with sample thickness. Ó 2019 Elsevier Ltd. Peer-review under responsibility of the scientific committee of the International Conference on Nano Science & Engineering Application (ICONSEA-2018) Centre for Nano Science and Technology, ICONSEA- 2018. 1. Introduction After the discovery of Graphene by K. S. Novoselov and A. K. Geim, the layered materials have experienced a tremendous resur- rection. Graphene, due to its interesting and exceptional mechani- cal, electronic and optical properties [1,2] drawn the attention to other 2D materials such as transition metal dichalcogenides (TMDs). TMDs are generally semiconductors which show a band gap modulation from indirect to direct, when thickness is varied from bulk to monolayer. TMDs show strong light-matter interac- tions resulting considerable amount of light absorbing particularly in visible range. This is because of the band nesting and van Hove singularities in density of states in these materials. Moreover due to the strong quantum confinement effect and reduced dielectric screening they exhibit large excitonic energy. Also quantum con- finement effect induces the formation of tightly bound trions in mono layer TMDs which indeed make these materials suitable for promising opto-electronic applications. Transparent and flexi- ble opto-electronics has rich and diverse application across the modern world. TMDs can be used as conductors, semi conductors, light emitters and optical absorbers in applications including transparent and wearable electronics [3]. Also they can be used as inter- band tunnel FETs which offer lower power consumption compared to ancestor transistors [4]. For example, the FETs based on MoS 2 monolayer have shown on/off ratio over 10 8 at room tem- perature [5]. TMDs such as MoS 2 , WS 2 , TiS 2 have got many interest- ing applications such as in batteries [6], light harvesting [7] etc. Monolayer TMDs of MoS 2 , MoSe 2 , WS 2 , WSe 2 are able to absorb up to 5–10% of incident visible light despite thickness being less than 1 nm. Compared to traditional semiconductors like GaAs and Si of similar thickness, the magnitude of absorption is high. Researchers from MIT have recently developed a new solar cell using Graphene and MoS 2 [8]. The low absorption and good con- ductivity of Graphene makes the solar cell a good transparent elec- trode whereas the good absorption of MoS 2 enabled it to be an optically active material. Some recent works have manifested the importance of simple, large area synthesis of MoS 2 on different flexible substrates using a solution process strategy for potential applications of MoS 2 - nanostructures in electronics, optoelectronics and energy storage [9,10]. Photodetection studies reveal that the defects introduced https://doi.org/10.1016/j.matpr.2019.05.423 2214-7853/Ó 2019 Elsevier Ltd. Peer-review under responsibility of the scientific committee of the International Conference on Nano Science & Engineering Application (ICONSEA-2018) Centre for Nano Science and Technology, ICONSEA-2018. ⇑ Corresponding author. E-mail address: kuntala.b@iist.ac.in (K. Bhattacharjee). Materials Today: Proceedings xxx (xxxx) xxx Contents lists available at ScienceDirect Materials Today: Proceedings journal homepage: www.elsevier.com/locate/matpr Please cite this article as: P. S. Sachidanand, M. M. Sreelal, S. Reshmi et al., MoS 2 nanostructures as transparent material: Optical transmittance measure- ments, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.05.423