Conversion of 4-N,N-dimethylamino-4’-N’-methyl-stilbazolium tosylate (DAST) from a Simple Optical Material to a Versatile Optoelectronic Material

Abstract

4-N,N-dimethylamino-4’-N’-methyl-stilbazolium tosylate (DAST) is an important optical material, but its poor conductivity limits applications in devices. To tackle this problem, we designed, prepared, and systematically investigated novel binary composite films that are composed of two-dimensional (2D) DAST and 2D graphene. Results indicate that both electrical and optical properties of DAST can be significantly improved by graphene addition. The negative steric effects of big DAST molecules that greatly trouble ex-situ synthesis can be efficiently overcome by in-situ synthesis, thus leading to better film quality and higher physical properties. Consequently, the in-situ composite film exhibits a low sheet resistance of 7.5 × 106 ohm and high temperature coefficient of resistance of −2.79% K−1, close to the levels of the most important bolometric materials for uncooled infrared detectors. Particularly, a new low temperature reduction of graphene oxide induced by DAST, which is further enhanced by in-situ process, was discovered. This work presents valuable information about the DAST–graphene composite films, their chemical structures, mechanisms, physical properties, and comparison on in-situ and ex-situ syntheses of graphene–based composites, all of which will be helpful for not only theoretically studying the DAST and graphene materials and expanding their applications, but also for seeking new optoelectronic sensitive materials.

Carbon nanotube versus graphene in modifying the electrical and optical properties of organic nonlinear optical material

“…Figure 3 indicates that three peaks at the diffraction angles of ~ 5.7°, 12.0°, and 24.7° (Fig. 3), assigned to the signals from the (− 212), (− 111), and ( 131) crystal planes of DAST (Xu et al 2015;Jerald Vijay et al 2010), respectively, were detected from the DAST film. This further confirms that DAST film with high crystallinity has been prepared by the simple spray-coating method, as implied by the SEM results (Fig.…”

“…In contrast, Chen emphasized that the temperature sensitivity and infrared absorption of cellulose can be modified by the addition of functionalized G, due to the formation of strong intermolecular hydrogen bonds (Chen et al 2018). Accordingly, we expected that the conductivity, temperature sensitivity, and optical properties of DAST can be similarly modified by the addition of CNT or G (Xu et al 2014(Xu et al , 2015. Despite these, we are still troubled by the question: which one is better, CNT or G, in modifying the electrical and/or optical properties of DAST?…”

“…Firstly, DAST was synthesized and purified according to the methods recently reported (Xu et al 2014). Secondly, to yield DAST-G composite films with high uniformity and excellent properties, the DAST-G composites used in this work were prepared by an in-situ synthesis method (Xu et al 2015), i.e. preparation of the binary DAST-G composite films by addition of graphene during DAST synthesis.…”

Long‐Term‐Stable Strong Second Harmonic Generation in Flexible DAST−PVDF Composite Films Realized by the Interface Interactions

“…Preparation of DAST−PVDF Composite Films: In this work, DAST− PVDF composite films with various DAST compositions were prepared by a solution casting method. The DAST used in this work was synthesized and purified by recrystallization, [46] while the PVDF powders (MW = 530 000) used in this work were purchased from Sigma Aldrich. PVDF powders were mixed with the self-synthesized and purified DAST powders at different weight percentages (1, 2, 4, 5, 6, 8, 10, and 15 wt% DAST).…”

Growth of 4-N,N-Dimethylamino-4'-N'-methyl-stilbazolium Tosylate (DAST) Organic Single Crystals Controlled by Oleic Acid

“…4-N,N-dimethylamino-4 -N -methyl-stilbazolium tosylate (DAST) organic single crystals have attracted considerable attention, owing to their large nonlinear optical (NLO) susceptibility, high electro-optical (EO) coefficient, and low dielectric constant [1,2]. Wide applications of DAST crystals include optical frequency conversion and information processing, terahertz (THz) wave generation and detection, and light-matter coupling [3][4][5][6], etc. For the practical applications, DAST single crystals with a large size, high crystallinity, and low defect density are generally required, by which higher NLO and EO properties can be achieved [7,8].…”