The Photoluminescence and Vibrational Properties of Black Phosphorous Sheets Chemically/Electrochemically Functionalized in the Presence of Diphenylamine

In this work, new information concerning the optical properties of black phosphorus (BP) sheets chemically/electrochemically functionalized with diphenyl amine (DPA) and its macromolecular compound (poly(diphenylamine) (PDPA)) in the absence/presence of phosphotungstic acid (PTA) is reported. Raman scattering and FTIR spectroscopy studies indicate that the interaction of BP with PTA leads to the elimination of the PxOy layer onto the surface of the BP sheets. In the case of the chemical interaction of BP with DPA, the reaction product corresponds to DPA chemically functionalized BP sheets having an imino-phosphorane (IP) structure. The electrochemical oxidation of BP sheets chemically functionalized with DPA in the presence of PTA leads to an increase in the weight of P-N bonds as a consequence of the generation of PDPA doped with the PTA heteropolyanions, as shown by FTIR spectroscopy and Raman scattering. This process is evidenced by a shift of the Raman line from 362 cm(-1) to 378 cm(-1), assigned to the A(1g) mode. This change was explained by taking into account the compression of the layers containing P atoms, which is induced by PDPA macromolecular chains. The decrease in the intensity of the PL spectra of DPA as well as PDPA, in the presence of BP, indicates that BP acts as a PL quenching agent for these compounds. A preferential orientation of the PDPA doped with the PTA heteropolyanions on the surface of BP sheets is highlighted by the variation of the binding angle of the PDPA on the surface of BP sheets from 44.7 degrees to 39.9 degrees.

Automated summary

This work investigates the optical properties of black phosphorus (BP) sheets chemically/electrochemically functionalized with diphenyl amine (DPA) and its macromolecular compound poly(diphenylamine) (PDPA) in the absence/presence of phosphotungstic acid (PTA). The interaction of BP with PTA leads to the elimination of the PxOy layer on the BP surface. When BP chemically interacts with DPA, the resulting product is chemically functionalized BP sheets with an imino-phosphorane (IP) structure. Electrochemical oxidation of DPA-functionalized BP sheets with PTA increases the weight of P-N bonds, generating PDPA doped with PTA heteropolyanions. This process is confirmed by FTIR spectroscopy and Raman scattering. The study also reveals that BP acts as a PL quenching agent for DPA and PDPA, with a preferential orientation of PDPA doped with PTA on the surface of BP sheets.