Journal Article

Two-dimensional (2D) metal-acetylide frameworks (M-AFs), a novel class of 2D materials, demonstrate significant potential in optics and photonics due to their tunable optical and electrical properties, which is achieved through the incorporation of polarizability and spin-orbit coupling of single-metal centers into the graphdiyne (novel allotrope of carbon) frameworks via metal-bis(acetylide) linkages (-C equivalent to C- M-C equivalent to C-). Here, 2D mercury (II)-acetylide framework nanosheets (Hg-H2TPP) were prepared using liquid-phase exfoliation from their bulk counterparts. The incorporation of heavy HgII ions led to modifications in the electronic band structure, as evidenced by room-temperature photoluminescence and absorption spectra, indicating potential applications in the near-infrared (NIR) range. The nonlinear optical (NLO) properties of the 2D nanosheets were evaluated by measuring the nonlinear absorption coefficients (beta). These coefficients ranged from-10.5 cm GW-1 (saturable absorption SA) to 10.9 cm GW-1 (reverse saturable absorption, RSA), demonstrating the nanosheets' potential as both saturable absorbers (SABs) and optical limiters. The observation that NIR-NLO properties were achieved only after the incorporation of HgII ions underscores the importance of material engineering in M-AF systems. To further assess the potential applications of this engineered material, Hg-H2TPP-based SABs were developed for NIR photonic devices. By utilizing these SABs, stable Q-switched and mode-locked lasers at 1560 nm were generated, yielding pulse widths (repetition rates) of 3.56 mu s (38.33 kHz) and 779 fs (7.69 MHz), respectively. The identification of these novel photonic properties and applications indicates that 2D M-AFs possess significant potential for future ultrafast nonlinear optoelectronic devices.