Synthesis Of Nano-materials Based On Pigment-protein Complexes And Its Photoelectric Performance Of DSSC

Anoxygenic photosynthetic bacteria can effectively carry out the photo induced electron transfer as a kind of natural solar cell. The main component of photosyntheti c pigment protein complexes has a rich source, wide spectrum and high photoelectric conversion function. The performance of PPC in photovoltaic cells exist many probl ems: the electron transfer efficiency. photocurrent and photoelectric conversion effi ciency is generally low. Now, researches of LHC from plants used as a sensitizer in Dye-sensitized solar cells?DSSC? showed the advantages. Nano materials have unique optoelectronic properties and compatibility with biological materials, can fix protein, promote the electron transfer between the electrode. The existing research is mainly PPC and carbon nanotubes, metal or metal oxide electrode by direct adsorp tion or chemical crosslinking combination. But directly to use PPC as a template for the synthesis of nano composite materials for DSSC has not been reported.We choosed light harvesting pigment protein complexes?LH2? of Rhodopseudomonas palustris as a natural photosensitizer source material, to study the interaction between LH2 and Au, Ag metal ions, and prepared nano-metal composite materials based on LH2, then applicated in the photoelectric conversion properties of DSSC. The main results are as follows:LH2 and Au ion reaction equilibrium was reached within 20 s. The absorption intensity of LH2 at the wavelength of 803 nm and 855 nm decreased with the increase of the amount of HAu Cl₄, and has a static fluorescence quenching effect on LH2,causing damage to the substructure of protein. Ag NO₃ had no significant influence on LH2,maintain the relative stability of protein structure. Compared with several metal ions?KCl?Ba Cl2?Mg Cl2?KMn O4?K2Cr O4?Na2Mo O4? and metal ions found that manganese ions has a certain effect on protein absorption peak.When we add Na BH4 after mixing LH2 and HAu Cl₄, the reaction reached equilib rium in 20 s, the absorption peak of LH2 decreased and a characteristic absorption peak appeared at 525 nm shows that we synthesised the nano metal composite. When we minxing LH2, metal precursors and Na BH4 at the same time, the characteristic absorption peak decreased to a lesser extent, some gold nanoparticles formated,which had no effect on the protein spectrum.The reaction reached equilibrium in10 min between LH2 and Ag NO₃ was 10 min and the characteristic absorption peak of nabosilver appeared at about 400 nm.Gold nanoparticles can separate in precipitation in 60% ammonium sulfate salinsi ty. Only a part of nano silver can precipitate in 80% ammonium sulfate salinity, the rest remained in the supernatant. LH2-gold nanocomposites completely separated in aerosol form in 80% salinity gradient. LH2-nano silver compound can separate in aerosol form with 80% ammonium sulfate salinity, and the silver nanoparticles did not combined with LH2 exist in the supernatant. In the suitable salinity that we can successfully separate gold nanoparticles and LH2- nano metal composite material.For the LH2 sensitized DSSC, the photoelectric properties have no difference wh en protein in the low concentration range?<0.37 ?mol/L?. LH2?0.147?mol/L? had the highest photoelectric conversion efficiency of 0.271% in the adsorption of 48h; When the molar ratio of HAu Cl₄/LH2 is 40,240,500,1200; we synthesised four nanoco mpo sites. We got the best photoelectric conversion efficiency when the adsorption time is24 h, The best ? and Isc of DSSC is 0.441% and 0.790 m A/cm2 when the molar ratio of 500, and Compared with the LH2 sensitized DSSC, the photoelectric conversion efficiency increased 195% and 98%. When the molar ratio of Ag NO₃/LH2 is 40,240,500; we synthesised nanocomposites. And we got the best photoelectric conver sion efficiency of the three nanocomposites in different adsorption time. The best ?and Isc of DSSC is 0.379% and 0.798 m A/cm2 when the molar ratio of 500, and Com pared with the LH2 sensitized DSSC, the photoelectric conversion efficiency incr eased 154% and 101%. LH2- nano composite materials can improve the photo elect ric conversion efficiency and photocurrent of DSSC in a certain extent.The photoelectric properties of composite materials sensitized DSSC in different Concentration: For the LH2-gold nanoparticle composites, The ? of high concentra tion of sample is 0.12%, increased about 81% than the low concentration sample; For the LH2-silver nanoparticle composites, The ? of high concentration of sample is0.262%, increased about 164% than the low concentration sample. When synthesis composite in Quantitative metal with different concentrations of protein, then sen sitizatied DSSC. For the LH2-gold nanoparticle composites, The ? of composite syn thesized by high concentration of protein was 0.317%, increased about 380% than the low concentration of protein. For the LH2-silver nanoparticle composites, The ? of high concentration of sample was 0.248%, increased about 151% than the low concentration of sample. The results showed that the introduction of nano-materials can improve the catalytic activity of Ti O2 thin film and the electron transfer efficiency inside the light anode.But the damage to the protein will reduce its photoelectric conversion efficiency.