7th IMRMPT

Abstract

Abstract information

English title:	Improvement in the conductivity of transparent conductive silver nanowire thin films through thermal and mechanical processes.
Spanish title:	Mejoramiento de la conductividad de pel�culas delgadas de nanocables de plata conductores transparentes a trav�s de procesos t�rmicos y mec�nicos.
English abstract:	The wide expansion of optoelectronic devices has produced the massive exploitation of different materials and the achievement of new ones. Some of those demand conductive materials which on being synthesized in thin film shape have as high charge carrier density as possible in its conductive band while allow the transmission of visible light, that means, conductive and transparent layers that can be used as transparent electrodes in devices like solar cells, LEDs, OLEDs and touch screens. Currently, the ITO (Indium Tin Oxide) has been used to this propose, a composition which has some drawbacks, like the fact that Indium is a scarce element and the films have ceramic properties that make them useless in flexible devices. For that, it is necessary to find out a new alternative to replace it [1,2]. Some candidate are organic and nanostructured materials. By our side, we have worked with silver nanowires (Ag NW) to make thin films obtaining promising results. We fabricated the Ag NW films by the Spin Coating process, which is a cheap and easy method [2,3]. One of the purposes is to find the best parameters of film fabrication, here each film was made with a quantity of three drops of material dissolved in ethanol, scattered over the glass substrate by rotation with an angular frequency of 3000RPM for 3 min at room temperature. Just a solvent fraction is evaporated in the processes of rotation; therefore, the films are dried at 100 �C during 10 min. After fabrication, the films are characterized as follows: the electrical properties were measured by four-point probe technique, finding sheet resistances lower than 30 Ω/sq, the optical properties by transmittance which gave an average value of 75% at 550 nm wavelength and the morphological and structural properties with SEM [3]. These results allow us to augur the nanostructured films as promissory candidates to replace the ITO. Despite these results, there are some drawbacks to solve, for example, the high contact resistance between nanowires. Because of this last, we have probed two different extra processes to try to improve the electrical contact between the nanowires conforming the thin film. This processes pretend as well getting more homogenous films without affecting its light transmittance [4]. The first one is the nanowire welding by heat treatment. In this method the films are exposed to high temperatures (120-190 �C) during different time intervals, achieving a kind of junction in some of the contacts and reducing the sheet resistance in a percentage magnitude of up to 50%. In this process it was observed the nanowires degradation after a certain temperature. The second applied method is the application of pressures on the films; in this method, we applied a force between 2 and 10 Ton-Force during different time intervals over the films surface achieving a sheet resistance decrease in a percentage magnitude of up to 76%. The results show an important improvement in the electrical conductivity of the metallic nanowire films after the welding processes without apparent variations of thin film transmittance. References [1] Zhu, Y., Deng, Y., Yi, P., Peng, L., Lai, X., & Lin, Z. (2019). Flexible transparent electrodes based on silver nanowires: Material synthesis, fabrication, performance, and applications. Advanced Materials Technologies, 4(10), 1900413. [2] Hossinzadeh Khaligh, H. (2013). Silver nanowires electrodes fabrication characterization and device integration. Thesis. Waterloo Ontario Canad�. [3] Ding, Y., Cui, Y., Liu, X., Liu, G., & Shan, F. (2020). Welded silver nanowire networks as high-performance transparent conductive electrodes: Welding techniques and device applications. Applied Materials Today, 20, 100634. [4] Langley DP, Lagrange M, Giusti G, Jim�nez C, Br�chet Y, Nguyen ND, Bellet D (2014). Thermal annealing effects on silver nanowire networks. Nanoscale. 6(22):13535-43
Spanish abstract:	La gran expansi�n de los dispositivos optoelectr�nicos ha producido la explotaci�n masiva de diferentes materiales y la consecuci�n de otros nuevos. Algunos de ellos demandan materiales conductores que al ser sintetizados en forma de pel�cula delgada tengan la mayor densidad de portadores de carga posible en su banda conductora y permitan la transmisi�n de luz visible, es decir, capas conductoras y transparentes que puedan ser utilizadas como electrodos transparentes en dispositivos. como c�lulas solares, LED, OLED y pantallas t�ctiles. Actualmente se ha utilizado para esta propuesta el ITO (Indium Tin Oxide), una composici�n que presenta algunos inconvenientes, como el hecho de que el Indio es un elemento escaso y las pel�culas tienen propiedades cer�micas que las hacen in�tiles en dispositivos flexibles. Para eso, es necesario encontrar una nueva alternativa para reemplazarlo [1,2]. Algunos candidatos son los materiales org�nicos y nanoestructurados. Por nuestra parte, hemos trabajado con nanohilos de plata (Ag NW) para fabricar pel�culas delgadas obteniendo resultados prometedores. Fabricamos las pel�culas Ag NW mediante el proceso Spin Coating, que es un m�todo econ�mico y f�cil [2,3]. Uno de los prop�sitos es encontrar los mejores par�metros de fabricaci�n de pel�culas, aqu� cada pel�cula se elabor� con una cantidad de tres gotas de material disuelto en etanol, esparcidas sobre el sustrato de vidrio por rotaci�n con una frecuencia angular de 3000 RPM durante 3 min a temperatura ambiente. . Solo una fracci�n de solvente se evapora en los procesos de rotaci�n; por lo tanto, las pel�culas se secan a 100 �C durante 10 min. Despu�s de la fabricaci�n, las pel�culas se caracterizaron de la siguiente manera: las propiedades el�ctricas se midieron por la t�cnica de sonda de cuatro puntos, encontrando resistencias de l�mina inferiores a 30 Ω/sq, las propiedades �pticas por transmitancia que dieron un valor promedio del 75% a una longitud de onda de 550 nm y las propiedades morfol�gicas y estructurales con SEM [3]. Estos resultados permiten augurar a las pel�culas nanoestructuradas como candidatas promisorias para sustituir a la ITO. A pesar de estos resultados, existen algunos inconvenientes a resolver, por ejemplo, la alta resistencia de contacto entre nanohilos. Debido a esto �ltimo, hemos probado dos procesos adicionales diferentes para intentar mejorar el contacto el�ctrico entre los nanocables que conforman la pel�cula delgada. Este proceso pretende adem�s obtener pel�culas m�s homog�neas sin afectar su transmisi�n de luz [4]. El primero es la soldadura de nanohilos por tratamiento t�rmico. En este m�todo las pel�culas se exponen a altas temperaturas (120-190 �C) durante diferentes intervalos de tiempo, logrando una especie de uni�n en algunos de los contactos y reduciendo la resistencia de la l�mina en una magnitud porcentual de hasta el 50%. En este proceso se observ� la degradaci�n de los nanocables despu�s de cierta temperatura. El segundo m�todo aplicado es la aplicaci�n de presiones sobre las pel�culas; en este m�todo, aplicamos una fuerza entre 2 y 10 Ton-Fuerza durante diferentes intervalos de tiempo sobre la superficie de las pel�culas logrando una disminuci�n de la resistencia de la l�mina en una magnitud porcentual de hasta un 76%. Los resultados muestran una mejora importante en la conductividad el�ctrica de las pel�culas de nanoalambres met�licos despu�s de los procesos de soldadura sin variaciones aparentes en la transmitancia de la pel�cula delgada. Referencias [1] Zhu, Y., Deng, Y., Yi, P., Peng, L., Lai, X., & Lin, Z. (2019). Flexible transparent electrodes based on silver nanowires: Material synthesis, fabrication, performance, and applications. Advanced Materials Technologies, 4(10), 1900413. [2] Hossinzadeh Khaligh, H. (2013). Silver nanowires electrodes fabrication characterization and device integration. Thesis. Waterloo Ontario Canad�. [3] Ding, Y., Cui, Y., Liu, X., Liu, G., & Shan, F. (2020). Welded silver nanowire networks as high-performance transparent conductive electrodes: Welding techniques and device applications. Applied Materials Today, 20, 100634. [4] Langley DP, Lagrange M, Giusti G, Jim�nez C, Br�chet Y, Nguyen ND, Bellet D (2014). Thermal annealing effects on silver nanowire networks. Nanoscale. 6(22):13535-43
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Speaker:

Authors

Name	Institution	Email
Andr�s Mauricio Bernal Forigua	Universidad Nacional de Colombia	ambernalf@unal.edu.co
Angel Miguel Ardila Vargas	Universidad Nacional de Colombia	amardilav@unal.edu.co

Presentation

Room:	Principal Room
Date:	June 7, 2023
Hour:	09:00 - 09:20

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7^th IMRMPT
Seventh International Meeting for Researchers in Materials and Plasma Technology

Previous editions:

        1st IMRMPT 2011
        2nd IMRMPT 2013
        3rd IMRMPT 2015
        4th IMRMPT 2017
        5th IMRMPT 2019
        5+1 IMRMPT 2021

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