Pulsed photoinitiated fabrication of inkjet printed titanium dioxide/reduced graphene oxide nanocomposite thin films

Abstract

This work reports a new technique for scalable and low-temperature processing of nanostructured TiO thin films, allowing for practical manufacturing of TiO-based devices such as perovskite solar cells at low-temperature or on flexible substrates. Dual layers of dense and mesoporous TiO/graphitic oxide nanocomposite films are synthesized simultaneously using inkjet printing and pulsed photonic irradiation. Investigation of process parameters including precursor concentration (10-20 wt%) and exposure fluence (4.5-8.5 J cm) reveals control over crystalline quality, graphitic oxide phase, film thickness, dendrite density, and optical properties. Raman spectroscopy shows the E peak, characteristic of anatase phase titania, increases in intensity with higher photonic irradiation fluence, suggesting increased crystallinity through higher fluence processing. Film thickness and dendrite density is shown to increase with precursor concentration in the printed ink. The dense base layer thickness was controlled between 20 and 80 nm. The refractive index of the films is determined by ellipsometry to be 1.92 ± 0.08 at 650 nm. Films exhibit an energy weighted optical transparency of 91.1%, in comparison to 91.3% of a thermally processed film, when in situ carbon materials were removed. Transmission and diffuse reflectance are used to determine optical band gaps of the films ranging from 2.98 to 3.38 eV in accordance with the photonic irradiation fluence and suggests tunability of TiO phase composition. The sheet resistance of the synthesized films is measured to be 14.54 ± 1.11 Ω/□ and 28.90 ± 2.24 Ω/□ for films as-processed and after carbon removal, respectively, which is comparable to high temperature processed TiO thin films. The studied electrical and optical properties of the light processed films show comparable results to traditionally processed TiO while offering the distinct advantages of scalable manufacturing, low-temperature processing, simultaneous bilayer fabrication, and in situ formation of removable carbon nanocomposites.

Nanostructured manganese oxides electrode with ultra-long lifetime for electrochemical capacitors

“…Our previous work found that the pulsed light irradiation results in the photoinitiated chemical reaction of the metal-acac molecules for the in situ formation of metal oxidereduced graphitic oxide nanocomposite thin lms. [30][31][32] In this work, it was also found that the Mn-acac precursor absorbs the visible light during the pulsed light irradiation, resulting in the formation of a nanostructured composite thin lm electrode. The rst pulse irradiation produced a sharp and loud sound, possibly because all the Mn-acac molecules transformed into MnO x -reduced graphitic oxide (rGO) aer the absorption of enough light energy.…”

“…Recently, our group reported a unconventional, low-cost and high-throughput pulsed photoinitiated approach to the in situ formation of threedimensional (3D) nanostructured composited thin lm composed of nanocrystalline transition metal oxide and reduced graphitic oxide through ash xenon lamp irradiation of metalorganic precursor lms. [30][31][32] Herein, we report a one-step thin-lm processing method and excellent cyclic stability and ultra-long cycle life of the electrode. Firstly, we have followed a spray-coating technique, which can be accomplished in less than a minute in ambient conditions, to spray Mn-acetylacetonate precursor solution onto the Pt-coated Si substrate.…”

Microwave characterization of nanomaterials using planar slot resonator

“…On the other hand, the performance and stability of lithium-ion batteries and supercapacitors have been shown to be improved by Al 2 O 3 -based nanocomposites [18,19]. Titanium dioxide (TiO 2 ) and its nanocomposites also have notable dielectric properties for a wide range of electronic applications, such as solar cells, gas sensors, and memristors [20][21][22]. In recent times, [23].…”