The Applications Of Sandwich-type Silicotungstates Modified TiO₂ Microspheres In Photoanode Of Dye-Sensitized Solar Cells

With the problems of energy shortages being more and more serious,a variety of solar cells have been studied and applied into practical production in which the DSSC is a kind of important trend.The photoanode is a crucial part of DSSCs,which can make use of optical energy to transfer electrons to external circuit.Enhancing the light absorption of photoanodes,accelerating the transport of electrons and retarding recombination of charges can obviously promote the photoelectric performances of DSSCs.By adjusting the elementary composition or structures of POMs,the photosensitizer which can absorb light at nearly full spectrum and the POMs which can match the energy level of semiconductors could be obtained.As a result,POMs with stable structures and properties are applied into photoanodes of DSSCs.The sandwich-type POMs have more active sites and the tetranuclear transition metal clusters have more centers of transition metals,which have utilization potentiality in optics and catalysis.In this paper,the sandwich-type silicotungstates doped TiO₂ respectively were applied to the photoanodes of dye-sensitized solar cells?DSSCs?for the first time,enhancing the current density and photoelectric conversion efficiency of the cells.1.TiO₂ nanospheres were prepared by hydrolysis of isopropyl titanate,the size of TiO₂particle is about 50 nm.The TiO₂ based photoanode can get higher efficiency than P25 based photoanode.So we directly applied the sandwich-type POMs doped self-made TiO₂ into the photoanode,which is different from the previous literature.2.The photoanode materials with different mass fractions of POMs were prepared respectively,aimed at finding the best quality ratio of POMs which can get the best PCE.The results showed that the best efficiency of photoanode was obtained when the mass fraction of POMs was 0.8%.Then three sandwich-type POMs were used to modify TiO₂ with the mass fraction of 0.8%,through comparison testing,0.8%Ni₄ modified TiO₂ photoanode obtained the highest PCE.3.The J_sc,V_oc and FF of Ni₄ 0.8%is 18.79 mA·cm^-2,0.71V and 0.595 respectively.Ni₄modified TiO₂ photoanode has the highest PCE?7.94%?of the three kinds of sandwich-type POMs and the longest electron lifetime?28 ms?,so the energy level of Ni₄ is characterized and studied.The results show that Ni₄ is a very good electronic acceptor,which can effectively retard the recombination of electrons.