Localized Excitons in Zn-Porphyrin Covalently Functionalized MoS<sub>2</sub> and WS<sub>2</sub>
Rubén Cantón-Vitoria, T Hotta, Yuri Tanuma, Ioanna K. Sideri, Nikos Tagmatarchis, Chris Ewels, Ryo Kitaura
Abstract
We successfully functionalized MoS 2 and WS 2 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/cm 2 in the near-infrared (NIR) region (1.40–1.51 eV), which originates from charge-separated states between ZnP and WS 2 . 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 WS 2 . 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 WS 2 and MoS 2 against atmospheric photodegradation. Theoretical modeling supports these findings, suggesting an intimate relationship between orbitals in the ground and excited states of porphyrin and TMDs.