in situ COMPLEXES OF SELF-ASSEMBLED FILMS OF CONJUGATED POLYMERS WITH PbS NANOPARTICLES AND THEIR PHOTOVOLTAIC PROPERTIES

Full conjugated multilayer thin films fabricated by the alternate adsorption of partially doped polyaniline (PANI) as a polycation and water-soluble poly (4-carboxyphenyl) acetylene (PA) as a polyanion were used as nanoreactors to study the in situ preparation of PbS nanoparticles. First, the self-assembled multilayers were immersed in a 1 mol/L NaOH solution to fabricate a controlled content of free carboxylic acid binding groups. Chemical reaction within the polymer film was initiated by absorbing Pb²⁺ from a 0.4 mol/L aqueous solution of Pb(Ac)₂ and followed by exposing the film to H₂S gas. UV-Vis absorption studies reveal that the absorption spectral profiles of the films are dependent on the dipping time of the film in the Pb (Ac)₂ solution. AFM and TEM microscopic examinations of the films reveal that PbS crystals with rhomboid structures are formed in the films. The particles of narrow size distribution stand vertically on the film plane. Due to being doped by PbS, the photoelectric conversion property of ultra-thin composite films, which can be measured with a conventional three-electrode photoelectrochemical cell using 0.5 mol/L KCl solution as the supporting electrolyte, is improved obviously. The results show that the value of the photocurrent for an 8-layer film is 3 times higher than that of the original film.