Localized Excitons in Zn-Porphyrin Covalently Functionalized MoS₂ and WS₂

Abstract

We successfully functionalized MoS2 and WS2 with Zn-porphyrin through 1,2-dithiolane addition. This creates mixed 0–2 dimensional materials since porphyrins are discrete on the basal plane of TMDs. This localization results in a new emission band with a 3.5 ns lifetime at 77.5 K with an excitation power of 17 W/cm2 in the near-infrared (NIR) region (1.40–1.51 eV), which originates from charge-separated states between ZnP and WS2. The optical response of excitonic species, including trion, biexcitons, and excitons, is substantially enhanced at the porphyrin absorption region, supporting electron transfer between ZnP and WS2. Sensing time-response improves after functionalization, suggesting that electrons injected from ZnP to TMDs contribute to filling trap states. Incorporating ZnP also enhances the stability of WS2 and MoS2 against atmospheric photodegradation. Theoretical modeling supports these findings, suggesting an intimate relationship between orbitals in the ground and excited states of porphyrin and TMDs.

Insulating 6,6‐Phenyl‐C61‐butyric Acid Methyl Ester on Transition‐Metal Dichalcogenides: Impact of the Hybrid Materials on the Optical and Electrical Properties

“…[34,35] On the other hand, TMDs (MoS 2 , MoSe 2 , MoTe 2 , WS 2 , WSe 2 , WTe 2 , MoO 2 and WO 2 ) were synthesized by chemical vapor deposition (CVD), employing NaCl as a promotor. [9,32,33,36] All the conditions are shown at supporting information and table S1. Among all the nanomaterials mentioned, MoS 2 , WS 2 , MoSe 2 , and WSe 2 exclusively exhibit semiconducting characteristics.…”

“…Briefly, [6,6]‐Phenyl C 61 butyric acid methyl ester (PCBM) was hydrolyzed according with the bibliography and further coupled with cysteine [34,35] . On the other hand, TMDs (MoS 2 , MoSe 2 , MoTe 2 , WS 2 , WSe 2 , WTe 2 , MoO 2 and WO 2 ) were synthesized by chemical vapor deposition (CVD), employing NaCl as a promotor [9,32,33,36] . All the conditions are shown at supporting information and table S1.…”

“…The CVD growth of all the TMDs was performed using a separator temperature controller AFM-9P-III ASH. [9,32,36] The temperature controller allowed precise control of the growth conditions during the chemical vapor deposition process. Additionally, the Argon flow was monitored using a Horiba STEC controlled unit PE-D2O.…”

“…Aggregates or non-covalent species were removed by simple washings. [32] ZnP was completely insulated in regions of 1 nm 2 and a new interlayer exciton with a lifetime of 3.5 ns was detected. In addition, thiols owned in antibodies can covalently react with the basal plane of MoS 2 or WS 2 , enabling the development of reusable biosensors for COVID-19 detection.…”

“…Concretely, the basal plane of MoS 2 and WS 2 were functionalized with Zn‐porphyrin (ZnP) bearing a dithiolane by simple mixing the materials during several days. Aggregates or non‐covalent species were removed by simple washings [32] . ZnP was completely insulated in regions of 1 nm 2 and a new interlayer exciton with a lifetime of 3.5 ns was detected.…”