Enhanced Photovoltaic Performance Of Phthalocyanine Sensitized Solar Cells By Polyoxometalates Modification

With the exhaustion of oil resources,the energy structure is transforming.At present,the new energy comes on the stage of history.The effective utilization of solar energy has become a hotspot in the world due to the unlimitedness of solar energy.And the solar cell is one of the main ways of utilizing solar energy.In view of the light-harvesting ability,thermal stability and low-cost,phthalocyanines have become suitable candidates used as dye sensitizers in DSSC.However,the power conversion efficiency using phthalocyanine dyes as sensitizers in DSSC is generally low.Polyoxometalates?POMs?,an efficient electron scavenger,can capture and transport photogenerated electrons from the conduction band of semiconductor and then improve the photovoltaic response.Silver nanoparticles can improve the light absorption of dyes,facilitate electron transport,reduce charge recombination and improve the electron injection efficiency due to their special optical and electronic properties,such as surface plasmon resonance effect.In this paper,we studied the photoconductive performance of Keggin-type tungsten-series POMs.What's more,in order to study the their influence on phthalocyanine-sensitized solar cells,POM and POM-AgNPs were introduced into the photoanode of cells.1.We fabricated a new DSSC using symmetric phthalocyanine zinc?II?as sensitizer.Compared with the unmodified device,the DSSC device with modified TiO₂ photoanode exhibited an enhanced photovoltaic performance.Such performances enhancement was ascribed to that the introductionof PW₁₂ into TiO₂ photoanode facilitated electron transport and reduced charger combination,which was demonstrated by electrochemicalim-pedance spectroscopy and open-circuit voltage decay measurements.2.We selected the POM as reductant and synthetised the Ag-POM nanohybrids facilely,and then fabricated the phthalocyanine-sensitized solar cells with Ag-POM/TiO₂ nanocomposite films.In comparison with the cell using POM/TiO₂ photoanode,20%increase in shor tcircuitcurrent densityand power conversion efficiency could be gained.This mainly is due to that silver nanoparticles can enhance the absorption of dye and accelerate electron transport.3.We prepared a series of films of Keggin-type tungsten-series POMs by blade coating technology and we explored the photoconductive performance of the POMs by the current-voltage curves experiments and photocurrent response experiments.We found that these POM samples could display steady and reproducible photocurrent responses,while PW₁₂ exhibited much higher photocurrent than others.In addition,the PW₁₂ device exhibited a fine sensing performance for ethanol gas,which is the first example of using only POM as the gas sensing material.