Indium Tin Oxide Is Touchscreen Technology - Case Study Example

INDIUM TIN OXIDE IS TOUCHSCREEN TECHNOLOGY By Name Course Instructor Institution City/State Date Table of Contents Indium Tin Oxide is Touchscreen Technology Abstract Indium tin oxide is undoubtedly the most broadly utilised transparent conducting oxides due to its two main properties, its optical transparency and electrical conductivity, in addition to the simplicity through which it may be deposited as a thin film. Akin to other transparent conducting films, a compromise has to be done between transparency as well as conductivity, given that increasing the concentration and thickness of charge carriers can improve the conductivity of the material, but lessen its transparency. The physical vapour disposition normally deposit Indium tin oxide’s thin films on surfaces, and frequently various sputter deposition or electron beam evaporation techniques are used. The report seeks to provide a critical analysis of Indium Tin Oxide, its application in touchscreen technology, how it is synthesised and processed, and how the properties of the material have enabled or improved the technology associated with it. Further, the report will describe any properties of the material that detract from its use and highlight any alternatives that are appearing in research or in the marketplace. Introduction Evidently, electronic devices of different sizes and shapes are currently featuring scores of different types of touchscreen design relying on their application as well as price point. The widely utilised technology on the tablets as well as Smartphones works by monitoring electrical current changes on the screen surface (Gilbert, 2014). Moreover, there are systems with the ability to track the vibration, reflection of light or sound waves, as well as shadow and light moving through the surface. System for monitoring electrical current perturbations on the screen’s conductive layer leads for consumer touchscreens. Indium tin oxide (ITO) is considered the best material for touch screen technology because of its transparent, very fine material that has high conductivity. ITO can as well handle the harsh setting that the tablet or smart phone is exposed to such as sweaty palms and pockets. ITO is widely utilized for building touch sensors as well as flat panel displays while televisions computer monitors, smart phones, and smartphones all utilize the compound to facilitate the swapping of pixels as well as to catalogue touch events. Indium Tin as mentioned by Gilbert (2014) is principally vital to the world's leading tablet and Smartphones producers due to its distinctive material properties ideal for touch screen applications: optically transparent, high conductivity, and can be manufactures easily in masses as thin films. Basically most of the newest tablets and smart phones create the conductive layer utilized for monitoring the electrical state changes as the user swipe and touch the screen. How the Material is Synthesised and Processed According to Khusayfan and El-Nahass (2013), the ITO thin films are currently the most utilised material, the attention of which has been attributed to its essential benefits as compared to the competing materials. Khusayfan and El-Nahass (2013) further note that ITO thin films are produced though utilisation of various techniques that includes reactive evaporation, direct current and radiofrequency sputtering, electron beam evaporation, pulsed laser ablation, sol-gel techniques, as well as spray pyrolysis. ITO as stated by Sarhaddi et al. (2010, p.452) is a form of transparent conducting oxides (TCOs) that is broadly utilised in numerous applications, because of their distinctive combination of high optical transparency as well as electrical conductivity. Precisely, as the most recognised and extensively utilised TCO material, ITO is a degenerate semiconductor (n-type) with a broad direct band gap. Recently, ITO has been utilised extensively as a transparent conducting electrode in numerous optoelectronic systems liquid crystal displays (LCD), dollar cells, in addition to other flat panel displays, as well for gas sensing devices and biomolecular microarrays (Sarhaddi et al., 2010, p.452). Latest ITO studies have mainly concentrated on properties as well as preparation of its powders, particularly on size and shape controlled nano-particles for applications in versatile devices. As evidenced in Sarhaddi et al. (2010, p.452) study, ITO nanoparticles are prepared through various wet chemical techniques, which include co-precipitation, sol-gel, emulsion technique, among others. Amongst the above-mentioned techniques, reference posts that the sol–gel process has extensively been due to its simple process of fabrication, inexpensive and easy appliances as well as the likelihood to control size of the particles together with their structural shapes. Lately, polymerizing-complexing combustion technique, a tailored Pechini process, deprived of any precipitation, is utilised for the semiconducting nano-particles preparation, such as ITO. This technique as mentioned by reference entails various organic fuels like EDTA urea, citric acid, hydrazine, as well as polyethylene glycol as polymerizing or complexing agents. Certainly, the PC technique offers powder that is more fine and homogenous as compared to other methods with metal-chelate complexes’ immobilization as well as creating metal complexes that are stable through heightening polymerization (Sarhaddi et al., 2010, p.456). Moreover, there exists scores of process parameters such as the sol–gel process in wet-chemical techniques that can affect the ITO powder properties, such as stoichiometric ratio, reactant pH, annealing temperature, as well as amount of supplemented tin dopant. Fig 1: Process of ITO nano-particle synthesis through the PC sol–gel method (Sarhaddi et al., 2010) In Sarhaddi et al. (2010, p.546) study, ITO nano-particles were successfully synthesized through the polymerizing-complexing sol-gel technique. After annealing nano-particles, results indicated that at high annealing temperatures, crystalline ITO nano-particles are created and all organic additives in the powders are removed. The Selected area (electron) diffraction as well as X-ray diffraction patterns exhibited In2O3-cubic phase within the nano-powders deprived of any sign of crystalline SnOx as an extra phase. Furthermore, based on X-ray diffraction and Transmission electron microscopy studies, when complexing agent used is citric acid in the ITO nano-particles synthesis it is possible to prevent agglomeration or grain growth of the particles and when ethylene glycol is added as an agent of polymerization to the precursor solution, it results in homogeneous particles distribution. Among the various methods of synthesising and processing ITO, electron beam evaporation according to reference appears to be the most effective technique for preparing ITO thin films. The synthesising process of the ITO films can impact the films microstructure, especially when the annealing temperature changes and this as a result could affect the electron transport and optical properties (Khusayfan & El-Nahass, 2013). Additionally, the intrinsic changes identification to ITO features is critical since such films are in the long run utilised in more applications, which involve more processes of treatment, which consequently, can change the primary optimized properties. Even though the annealing temperatures effect on the ITO films properties is immense, the topic has widely been ignored. Utilising quartz as substrate for validity heating of ITO films can allow for their intrinsic properties investigation when those films are at higher temperatures (Sarhaddi et al., 2010). Fig 2: ITO nano-particles TEM images annealed at different temperatures, (a) 350 oC, (b) 500 oC and (c) 650 oC (Sarhaddi et al., 2010) Table 2: Resistances of ITO thin films fabricated in different manner How the Properties of the Material Have Enabled or Improved the Touch Screen Technology Based on its properties like optical transparency as well as electrical conductivity in the visible range, and importantly due to their low fabrication costs, ITO has widely been utilized as a material for transparent electrodes in various types of display, and for sources of incandescent light. ITO is as well utilized in other applications, such as antiglare as well as antistatic coatings, anti-Electro Magnetic spam screens, in addition to conductive pastes (Psuja et al., 2009, p.1). ITO in its thinnest form is not just transparent, but also highly conductive. This as a result has led to its utilization in world’s most widely and popularly utilized touch screen technology. Besides that, it is practically simple to use as well as deposit ITO as a thin film; this as a result, makes it ideal for mass production through methods like evaporation, sputtering or physical vapour deposition techniques. ITO films’ high electrical conductivity leads to high reflectivity in the region of infrared that is used in radiative cooling prevention, windows’ thermal insulation, and so forth (Benoy et al., 2009, p.629). In recent times, the interest on depositing ITO film on polymer substrates has increased for organic light-emitting devices, light-emitting diode, as well as liquid crystal display applications. Table 2: ITO films X-ray diffraction data of different thickness (Benoy et al., 2009) Polymer substrates different from the traditional glass substrate, offer light weight displays that are more resistant to damage attributed to impact; thus, making them appropriate for mobile devices such as Smartphones and tablet. An OLED or LCD created on materials that are flexible, like plastic and metal, can be designed into any size and shape (Mohameda et al., 2009, p.705). Although the technical obstacles are substantial, flexible displays made by ITO materials can result in significant achievement in producing efficiency. Rather than depending on batch processes utilized for liquid crystal displays, the displays can be produced through continuous roll-to-roll processing system, much akin to that of utilized for printing newspapers. Thanks to high optical transparency and high conductivity properties, ITO thin films have extensively been utilized in numerous optoelectronics applications as transparent conductive electrodes like LCDs, solar cells, plasma displays, and OLED. ITO films’ low-resistivity values are mostly attributed to high concentrations of the carries caused by tin dopants as well as oxygen vacancies. Besides that, the high transparencies within the near-IR and visible regions are attributed to the broad band gap. As stated by Mohameda et al. (2009, p.706), the ITO films that is highly transmitting has a band gap higher than 3 eV in the visible region and therefore is desired in scores of applications. These films’ conductivity may be heightened by introducing numerous forms of dopants like tin, fluorine, antimony, and cadmium. Detracting properties and Alternatives for Touch Screen Technology As mentioned by reference, the ITO’s world market supply is dwindling with China being the main producer. Estimates point out that with the present consumption rate, indium reserves will not last more than eighteen years. Given that the ITO based displays margins are already very thin, worries concerning ITO material supply made displays producers to start searching for alternatives. Experts within the industry are arguing that indium will in the coming decade completely diminish, thus resulting into shortage of crucial elements needed for making touch screens. But reference argues that carbon atoms layer whose thickness is one atom thick, and which can be bent almost all ways can be used in place of ITO; thus, connoting that meaning it may as well be utilised in flexible displays, as well as to make present generation displays more likely to continue working when undergoing shock damage. Amongst other existing alternatives silver nanowires is already in practice, and has been utilised in a number of devices which also includes flexible displays. Expectantly a cheap and effective material that can remain competitive will soon start surfacing in the mainstream device such as tablets and Smartphones. Based on the most recent market research carried out by BCC Research, it was established that by 2018, the worldwide marketplace for transparent conductive coatings will grow from 4.8 billion U.S dollars in 2013 to almost 7.1 billion, which is an 8 per cent compound annual growth rate (Reportlinker, 2015). In their study, BCC offers an industry overview based on the technologies utilising ITO or other transparent conductive coatings for the display, touch screen, and other application. Basically, the transparent conductive coating materials’ diversification capitalise on a number of issues associated with indium tin oxide such as limited supply of indium used for making ITO as well as ore situated in regions that are geopolitically sensitive, the process of thin film deposition is exceedingly expensive, tedious process of patterning for the display industries as well as touch screen, applications’ poor performances creating the need for low surface resistivity, high film transmission and flexibility, in addition to the inherent material toxicity. A number of materials have the ability to replace ITO in the in the next generation of touch screen tablets touch screen as well as smart phones, they include; Carbon nanotubes, Graphene, Gallium-doped Zinc Oxide, thin metal films, Aluminium-doped Zinc Oxide, silver nanowires hybrid materials, as well as Amorphous Indium-zinc oxide. As observed with ITO, its alternatives demand will exceedingly increase, and as a result, its availability and price will suffer. Importantly, industry experts together with the material scientists across the globe are looking for a more efficient ways of using and recycling Indium in addition to the development of alternatives that are more sustainable. But for now, the market price for touch screen components will continue increasing (Chinnock, 2014). In 2007, ITO has undisputed market share of 97.2 per cent mainly due to Touch-Screen as well as Flat Panel Displays.  However, ITO is expected to lose the market share to 75.3 per cent in 2016. In this case, flexibility has been considered as the key factor in the touch screen industry and every novel replacement for ITO should be able to provide, bendability in addition to other features superior to ITO even if electrical conductivity as well as transparency are to some extent worse.  This is because; flexible films are crucial features in touch panels, and other similar products. Conclusion In conclusion, it has been argued that the electron beam evaporation and polymerizing-complexing technique are effective method for synthesising and processing ITO, because they offer ITO powder that are more fine and homogeneous as compared to other techniques. Polymerizing-complexing technique forms metal complexes that are stable through increasing polymerization. Additionally, there are scores of process parameters in sol-gel process and other synthesizing techniques that affect the ITO powder properties, particularly its stoichiometric ratio, reactant pH, amongst others. ITO as evidenced in the report is not just utilized for touch screens; its unique properties have generated enormous global demand in a number of technologies: touch screens, LCDS, plasma screens, and LEDs. In summary, ITO originates from Indium, which akin to other 'rare' elements is turning out to be more and more limited and for that reason it is becoming even more valuable. But numerous alternatives have begun surfacing, and are expected to replace ITO in the future touch screen technologies. References Benoy, M.D. et al., 2009. Thickness dependence of the properties of indium tin oxide (ITO) FILMS prepared by activated reactive evaporation. Brazilian Journal of Physics, vol. 39, no. 4, pp.629-32. Chinnock, C., 2014. The End of ITO Dominance is in Sight. [Online] Available at: http://www.insightmedia.info/the-end-of-ito-dominance-is-in-sight/ [Accessed 1 April 2015]. Gilbert, N., 2014. Touch Screen Indium Tin Oxide (ITO). [Online] Available at: http://www.azom.com/article.aspx?ArticleID=9634 [Accessed 1 April 2015]. Khusayfan, N.M. & El-Nahass, M.M., 2013. Study of Structure and Electro-Optical Characteristics of Indium Tin Oxide Thin Films. [Online] Available at: http://www.hindawi.com/journals/acmp/2013/408182/ [Accessed 1 April 2015]. Mohameda, S.H., El-Hossarya, F.M., Gamalb, G.A. & Kahlidb, M.M., 2009. Properties of Indium Tin Oxide Thin Films Deposited on Polymer Substrates. ACTA PHYSICA POLONICA, vol. 115, no. 3, pp.704-08. Psuja, P., Hreniak, D. & Strek, W., 2009. Synthesis and characterization of indium-tin oxide. Journal of Physics, vol. 146, pp.1-10. Reportlinker, 2015. Transparent Conductive Coatings : Technologies and Global Markets. [Online] Available at: http://www.prnewswire.com/news-releases/transparent-conductive-coatings--technologies-and-global-markets-300048469.html [Accessed 1 April 2015]. Sarhaddi, R., Shahtahmasebi, N., Rokn-Abadi, M.R. & Bagheri-Mohagheghi, M.M., 2010. Effect of post-annealing temperature on nano-structure and energy band gap of indium tin oxide (ITO) nano-particles synthesized by polymerizing–complexing sol–gel method. Physica E, vol. 43, pp.452–57. Read More