Open Access ISSN: 2169-0022 Research Article Volume 10:5, 2021 Journal of Material Sciences & Engineering Efect of Di ferent Sized Multi Walled Carbon Nanotubes on the Parameters Afecting the Charge Injection Process of Methyl Red Dye Based Organic Device Abstract Present paper has been done to describe the parameters related to organic device’s process of charge injection and to observe how these parameters get affected by different sized multi walled carbon nanotubes such as 8 nm diameter, 30 nm diameter and 50 nm diameter respectively. Barrier height significantly affects the interfacial charge injection process. Image charge effect also plays a salient role in lowering interfacial barrier. Spin coating technique has been used to form these devices. To estimate the barrier height, the current-voltage characteristics of these devices have been analyzed. Threshold voltage and ideality factor of these devices were also estimated. All the above mentioned parameters were calculated in absence and presence of different sized multi walled carbon nanotubes to observe its effect on these parameters. The barrier height was also estimated by Norde method. Both the methods remained consistent in showing that multi walled carbon nanotubes reduced the interfacial barrier. Effective barrier height considering image charge effect was also decreased due to incorporation of multi walled carbon nanotubes. Lowering of these parameters indicated improved charge flow at the interface. This work will be informative as the lower threshold voltage will cause consumed power to decrease. As the interfacial charge injection process gets improved, device conductivity will be improved which will result in greater efficiency. Keywords: Barrier height • Charge injection • Image charge effect • Metal-organic dye interface • Methyl red dye • MWCNT • Norde method Sudipta Sen * and N.B. Manik Department of Physics, Jadavpur University, Kolkata, India *Address for Correspondence: Sudipta Sen, Department of Physics, Jadavpur University, Kolkata, India, Email: sagnike000@gmail.com Copyright: © 2021 Sudipta Sen, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Received date: 30 April, 2021; Accepted date: 14 May, 2021; Published date: 21 May, 2021 Introduction Organic electronic devices are easily compatible with fexible substrates. These materials can be produced in large scale compared to the inorganic ones as they can be easily processed. Organic materials are also of low cost and adjustable to band energies [1,2]. Despite certain advantages of these devices, there are certain limitations that do exist in these devices. One of the main limitations is low charge injection at metal organic (M/O) interface. Ineffcient charge movement from metal electrode to organic semiconductors can be attributed to the high contact barrier [3- 6]. In this context, it is of paramount importance to decrease contact barrier for improving the device performance. Here, in this work, the barrier height has been estimated as it hinders charge injection process of the device. The ideality factor and the threshold voltage of the device have also been estimated as these are also related to charge injection process. The term “threshold voltage” has been used as the device turn on voltage. When an organic device starts to conduct at a particular voltage, that particular voltage can be specifed as “threshold voltage” of that device. Generally, more than unity value of ideality factor ascribed to interfacial trap states between the metal and organic semiconductor as organic device is prone to traps [7,8]. Other researchers have also highlighted that the image charge effect may be the reason of the greater than unity value of the ideality factor [9,10]. Image charge effect also lowers the interfacial barrier which has also been studied in this work. Among organic materials, Methyl Red (MR) dye is used in this present work. Electrons delocalized in the benzene and azo groups form a conjugated system in dye molecular structure [11,12]. Its structure and abundance of π electrons allow us to use this dye in between Aluminium and Indium Tin Oxide (ITO) coated glass substrate to prepare the device. For different organic dye based devices, different researchers have used multi walled carbon nanotubes (MWCNT) as dye adsorbent for treatment of wastewater by removing methyl blue, methyl orange and methyl violet from aqueous solution [13-15] and researchers have also observed strong and broad band optical limiting in multi walled carbon nanotube suspensions [16]. In this work, MWCNT have been chosen due to its high aspect ratio, electrical and thermal conductivity and mechanical strength [17]. Different sized multi walled carbon nanotubes (MWCNT) such as 8 nm diameter, 30 nm diameter and 50 nm diameter MWCNT have been used to study their effects on contact barrier. Their effects have been studied on ideality factor and the threshold voltage as these parameters affect the device’s charge injection process. Image charge effect in presence of different sized MWCNT has also been studied in this work. The process of interfacial charge injection is generally analyzed by the theory of metal to semiconductor contact [18]. Our earlier works have characterized these organic devices by using Richardson-Schottky (RS) model [19,20]. Steady state current voltage characteristics of these devices have been analyzed to evaluate barrier height, ideality factor and threshold voltage. The contact barrier is also calculated by Norde method to check the consistency of the obtained result from the current voltage characteristics. The effective barrier height considering image charge effect