Photoluminescence and Raman spectroscopy studies on polyaniline/PbI2 composite

Functionalization of PbI2 with conjugated polymers (polyaniline-emeraldine base (PANI-EB) or polyaniline-emeraldine salt (PANI-ES)) is demonstrated by Raman and luminescence studies. PbI2/PANI hybrid material was prepared by electrochemical polymerization of aniline onto the PbI2 modified Pt electrode and mechanico-chemical reaction between the two constituents. PANI interacting with the PbI2 gives rise to new Raman bands at 80, 144 and 170 cm−1. First line reveals the formation of “stacking faults” that disrupt the I–Pb–I layers stacking along the c axis by the insertion of polymer molecules. The bands at 144 and 170 cm−1 are attributed to the vibrational mode associated with Pb-NHR″2 (R″=C6H4) bond. The functionalization of PbI2 with PANI-EB brings forth the PANI-ES form. Depending on the semiconducting (PANI-EB) or conducting (PANI-ES) properties of the polymer in the PbI2/PANI intercalated material, a partial or total collection of the charges generated under band to band irradiation is revealed by photoluminescence studies.

Experimental illustration of the extending along the c axis of a PbI2 single crystal by an intercalation process. In (a) is shown a crystal slide cleaved from a Bridgman-grown PbI2 crystal ingot and in (b) the same sample intercalated with pyridine obtained after an exposure for 24 h in a saturated atmosphere of pyridine.Figure optionsDownload as PowerPoint slide