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.