Investigation of charge carrier dynamics in Ti3C2Tx MXene for ultrafast photonics applications

The rapid advancement of nanomaterials has paved the way for various technological breakthroughs, and MXenes, in particular, have gained substantial attention due to their unique properties such as high conductivity, broad-spectrum absorption strength, and tunable band gap. This article presents the impact of the process parameters on the structural and optical properties of Ti3C2Tx MXene for application in ultrafast dynamics. XRD along with Raman spectroscopy studies, confirmed the synthesis of a single phase from their MAX phase Ti3AlC2. The complete etching of Al and increase in the interplanar distance is also observed on centrifugation at very high speed. The ultrafast transient absorption spectroscopy used to understand the effect of centrifuge speed on the charge carrier dynamics and ultrafast spectrum of MXene displayed that the carrier lifetime is critically influenced by rotation per minute (rpm) e.g. faster decay lifetime at 10k rpm than 7k rpm. The electronic relaxation probed using the time-resolved photoluminescence (TRPL) technique exhibits an average decay time of 5.13 ns and 5.35 ns at the 7k and 10k rpm, respectively, which confirms that the optical properties of the MXene are strongly affected by the centrifuge speed. The synthesized MXene at 10k rpm typically suggests that radiative processes due to longer decay lifetime and experiences fewer nonradiative losses, resulting in enhanced luminescence properties.Comment: 21 pages , 6 figure

Solution processed Li5AlO4 dielectric for low voltage transistor fabrication and its application in metal oxide/quantum dot heterojunction phototransistors

Li5AlO4, a well-known material for solid state electrolyte application, has never been considered hitherto as a gate dielectric of metal oxide thin film transistors (TFTs). Here we demonstrate the salient features of Li5AlO4 as a gate dielectric outperforming the conventional inorganic dielectrics used in TFTs. The high dielectric constant (k) of this insulator has been achieved by utilizing the improved capacitance contributed by mobile lithium ions (Li+) within the dielectric film. We have synthesized this dielectric via a cost-effective sol-gel method followed by a low-temperature annealing process yielding three phases such as amorphous-Li5AlO4 (a-Li5AlO4), a-Li5AlO4, and b-Li5AlO4 under different annealing conditions. Optimized TFTs fabricated with all of these three phases of Li5AlO4 on top of a highly doped silicon (p(++)-Si) wafer and a solution processed semiconducting layer of indium zinc oxide (IZO) exhibit an excellent TFT performance at different operating voltages. Among these three different types of TFTs, the device with an alpha-Li5AlO4 gate dielectric annealed at 500 degrees C shows the best device performance with an on/off ratio of 5 x 10(4) and an electron mobility of 21.4 +/- 2.16 cm(2) V-1 s(-1). In addition, this device requires the least drain voltage (<2 V) to reach the saturation drain current due to the higher Li+ mobility of the alpha-Li5AlO4( gate dielectric. This TFT performance on the p(++)-Si substrate is superior to that of a previously reported device with a sodium beta-alumina (SBA) gate dielectric, where the percentage of mobile ions within the dielectric material was comparatively much lower. Moreover, this dielectric requires B300 degrees C lower annealing temperature compared to the SBA dielectric. A metal oxide/quantum dot heterojunction phototransistor was fabricated by coating an IZO TFT with colloidal lead sulphide (PbS) quantum dots that shows a responsivity and a response time of 4.5 x 10(-4)A W-1 and 2.2 s respectively