Organic-inorganic hybrid silver benzeneselenolate (AgSePh, Ph = C6H5) has been actively studied in recent years as a rejuvenated 2D layered multi-quantum well (multi-QW) semiconductor, whose monolayer is a single QW that bears a 2D semiconducting SeAgSe polymeric network sandwiched between two layers of organic phenyl rings through Se-C bond linkages. We report here the area-scalable preparation of AgSePh thin films and their multi-QW-derived optically controlled excitonic properties. The well-known silver mirror reaction enables us to prepare area-tunable silver films, which are then converted to high-quality polycrystalline AgSePh thin films with lateral sizes ranging from 2 cm × 2 cm to 10 cm × 10 cm by reacting with Ph2Se2 vapor via an ethanol-assisted thermal evaporation process. Both small-area and large-area AgSePh thin films exhibit room-temperature-resolved multiple excitonic absorption bands (X1 at 2.71 eV, X2 at 2.73 eV and X3 at 2.81 eV) in the visible-spectral region, large exciton binding energy (Eb: ∼0.38 eV), and narrow-linewidth blue photoluminescence (PL) at 2.64 eV (∼470 nm). The quantum and dielectric effects arising from the multi-QW structure account for the presence of Coulomb-bound Wannier-Mott exciton states with different energy levels and high Eb, and especially the radiative recombination of the lowest-energy X1 excitons leads to the blue PL emission. Furthermore, AgSePh thin films are found to show good PL stability and surface wettability for organic solvents (e.g., ethanol and toluene). These area-tunable, blue-emissive AgSePh thin films would find wide use in environment-friendly luminescent materials (Pb/Cd-free), optical (bio)imaging, light-emitting devices, quantum optics, and organic optoelectronic devices.
Yang et al. (Wed,) studied this question.