Morphological Control of 2D Hybrid Organic–Inorganic Semiconductor AgSePh

Abstract

Silver phenylselenolate (AgSePh) is a hybrid organic–inorganic two-dimensional (2D) semiconductor exhibiting narrow blue emission, in-plane anisotropy, and large exciton binding energy. Here, we show that the addition of carefully chosen solvent vapors during the chemical transformation of metallic silver to AgSePh allows for control over the size and orientation of AgSePh crystals. By testing 28 solvent vapors (with different polarities, boiling points, and functional groups), we controlled the resulting crystal size from <200 nm up to a few μm. Furthermore, choice of solvent vapor can substantially improve the orientational homogeneity of 2D crystals with respect to the substrate. In particular, solvents known to form complexes with silver ions, such as dimethyl sulfoxide (DMSO), led to the largest lateral crystal dimensions and parallel crystal orientation. We perform systematic optical and electrical characterizations on DMSO vapor-grown AgSePh films demonstrating improved crystalline quality, lower defect densities, higher photoconductivity, lower dark conductivity, suppression of ionic migration, and reduced midgap photoluminescence at low temperature. Overall, this work provides a strategy for realizing AgSePh films with improved optical properties and reveals the roles of solvent vapors on the chemical transformation of metallic silver.

Light Emission in 2D Silver Phenylchalcogenolates

“…The free-exciton PLQY of the AgSePh film increased monotonically with decreasing temperature, approaching ∼0.25% at 5 K. The PLQY of the subgap defect-derived emission in AgSePh also increased monotonically with decreasing temperature, becoming the primary emission source at low temperatures (based on spectral integration). The total PLQY, including free-exciton and subgap emission, of the AgSePh film was estimated to be ∼2.1% at 5 K. These overall trends suggest the existence of thermally activated nonradiative recombination channels that become partially suppressed at low temperatures. , Strikingly, however, there also remains a strong nonradiative recombination pathway in AgSePh even below 10 K.…”

“…Silver phenylselenolate (AgSePh) and silver phenyltellurolate (AgTePh) films were prepared by a vapor-phase chemical transformation method. , Briefly, a 15 nm thick Ag film was deposited on a glass substrate by thermal evaporation, and then the silver-coated glass slide was placed inside a sealed pressure vessel containing deionized water and diphenyl diselenide (Ph 2 Se 2 ) or diphenyl ditelluride (Ph 2 Te 2 ) powder. After the vessel was heated to 100 °C for 3–4 days, the Ag film was transformed into a light yellow AgSePh film or a deep yellow AgTePh film (Figure b).…”

“…AgEPh (E = Se, Te) thin films were prepared by a chemical transformation reaction between metallic silver and Ph 2 E 2 (E = Se, Te). , Silver films with thickness of 15 nm were deposited on glass substrates by thermal evaporation with a deposition rate of ∼1 Å/s. After that, the prepared silver films, ∼30 mg of Ph 2 E 2 powder, and 200 μL of deionized water in separate open culture tubes were sealed together inside a microwave reaction vial.…”

“…Among the 2D MOCs reported so far, silver phenylselenolate (AgSePh), also known as “mithrene”, has attracted the most attention due to its natural blue (∼467 nm) emission. ,− It was shown that silver phenyltellurolate (AgTePh), known as “tethrene”, also crystallizes into a 2D structure at room temperature with the same monoclinic centrosymmetric space group C 2/ c as AgSePh. , (Note that AgSePh has also been reported in the P 2 1 / c structure, which is very similar in structure to C 2/ c .) However, AgTePh exhibits a strikingly different optical behavior from AgSePh despite the structural and compositional similarity, implying a different physical mechanism underlying light emission in AgTePh.…”

High Performance Gold Nanorods@DNA Self-Assembled Drug-Loading System for Cancer Thermo-Chemotherapy in the Second Near-Infrared Optical Window

“…However, one major obstacle, to date, is the limited choice of contrast agents in this spectral range. Common PTAs, including organic dyes [ 14 , 15 ], carbon nanomaterials [ 16 , 17 ], inorganic semiconductor materials [ 18 , 19 ], and precious metal materials [ 20 , 21 ], in this window are largely uncharacterized for their cytotoxicity. Among them, AuNPs, a precious metal material, have received widespread attention based on their outstanding physical and chemical properties, good biocompatibility, and excellent local surface plasmon resonance (LSPR) properties.…”