Application Of Natural Pigment In Dye - Sensitized Solar Cells

Dye-sensitized solar cell (DSSC) is a device to change solar energy into electricenergy, has benn studied extensively because of its integration of high efficiency,lowcost and facile fabrication. Currently, the light-to-electric energy conversionefficiency of the DSSC has reached more than12%. However, the use of theseexpensive Ru metals, derived from relatively scarce natural resources corresponds toa relatively heavy environmental burden. Plant pigmentation occurs due to theelectronic structure of the pigment interacting with sunlight to alter the wavelengthsthat are either transmitted or reflected by the plant tissue. They offer environmentalfriendliness, low-cost production, designable polychrome modules, simplepreparation technique and wide availability. Although the efficiencies obtained withthe natural dyes are below the requirements for large scale production, the results arehopeful and can boost additional studies oriented to the search of new naturalsensitizers and to the optimization of solar cell components compatible with suchdyes.In this paper,30types of natural dyes were extracted from flowers, fruits, leaves.These extracted dyes were characterized by UV–vis absorption spectra. Thephotoelectrochemical properties of the DSSCs using these extracts as sensitizerswere investigated. Extract obtained from mangosteen pericarp, grape peel, Lacy treephilodendron was performed as the sensitizer,The photovoltaic properties of DSSCssensitized were studied; The influence of pH with dye on the photoelectricperformance of DSSC was investigated; The dependence of UV-vis absorptionspectra and photovoltaic properties from the photo-anodes co-sensitized with twodyes were studied.(1)30types extract from plants and plant tissue used as sensitizer of DSSC. TheUV-vis absorption spectra of mangosteen pericarp, grape peel, Lacy treephilodendron were widest. η of the DSSC sensitized with mangosteen pericarp washighest, reached1.24%, the lowest only0.0777%, other of them are about0.3%.η ofthe DSSC sensitized with mangosteen pericarp, grape peel, Lacy tree philodendronwere1.24、0.81、0.573%respectively. (2) The pigment of grape peel absorbed the blue light and green light of480-600nm, the UV-vis absorption spectra of the photo-anodes sensitized with thepigment of grape peel was blur-shift. The IPCE of the DSSC sensitized with thepigment of grape peel were higher in390nm and510nm. The photovoltaicparameter JSC、VOC、FF、ηwere2.14mA/cm2、0.566V、0.667、0.81%respectively.When the value of pH was increase, the absorption spectra of480-600nm wasred-shift. When pH=8, the absorption peak was disappeared. When the photo-anodestreated with HCl, TiO2electrode treatment with HCl aim to enhance the conversionefficiency of DSSC. The photovoltaic parameter the of the photo-anodes treatedwith HCl, JSC、VOC、FF、η were3.186mA/cm2、0.621V、72.32%and1.43%respectively. The increase of JSCand η were48.5%and76.5%.(3) Mangosteen pericarp absorbed blue light around460nm. The absorptionspectra of the photoanodes sensitized with the pigment of Mangosteen pericarp wasblue-shift from540nm to470nm obviously. JSC、VOC、FF、ηwere2.57mA/cm2、0.77V、0.627and1.24%respectively. Contrast with grape peel, both JSCand VOCwere enhanced. When the value of pH was2, the UV-vis absorption spectra of thephoto-anode had been fine. JSCvalue was decreases drastically when the value of pH.The pigment of Lacy tree philodendron is green. It absorbed the light of300-500nm,and the red light of600-700nm. But the photo-anode sensitized with it absorbed thelight of430-450nm merely. JSC、VOC、FF and ηwere1.42mA/cm2、0.64V、0.632and0.573%respectively。(4) The Mangosteen pericarp/Lacy tree philodendron and Mangosteen pericarp/grape peel co-sensitized the photoanodes, two combinations of light absorptionrange than single sensitizing widening, the equivalent of two superposition. Theresistance of electron transmit among TiO2/dye/electrolyte, which DSSCco-sensitized with Mangosteen pericarp/Lacy tree philodendron, was minimum,combined with its light absorption performance, appears to be the highestconversion efficiency of solar cell. JSC、VOC、FF and η were1.4mA/cm2、0.626V、0.84and0.738%respectively。...