Electrospinning TiO2 nanofibers, nanoparticle/nanofibers as a photoanode for high performance dye sensitized solar cell

摘要

Dye sensitized solar cell(DSSC) possessed both low cost and high energy conversion efficiency has attracted considerabale research interests, enabling a promising next generation solar cell. DSSC based on TiO₂ photoanode is a low-cost, high efficient photovoltaic device for solar energy conversion. Conventional commercial photoanode consist essentially of anatase crystalline titanium dioxide which played a key role in dye adsorption and electron transport. However, nanoparticles were not conducive to the separation and transmission of electrons and holes. One-dimensional (1D) nanostructure photoanode was replaced the nanoparticle film, which provided a direct pathway improve the efficiency. TiO2 nanofibers(NF) synthesized via electrospinning, has evealed distinct properties as a photoanode in DSSC. An innovation of TiO₂ nanoparticle (NP)/TiO2 nanofibers double layers was fabricated to form composite photoanode in our work. These TiO2 NP/NF composite photoanodes have exhibited high performance applied in DSSC. The TiO2 NF was described in terms of crystallinity, morphology and chemistry through BET, XRD, TEM, EDX, FESEM, XPS, FT-IR, TG. After via sintering treatment, NF did not change significantly and was used as photoanode scattering layers in DSSC. Based on these TiO₂ NP/NF double layer as composite photoanode, the devices were sensitized with N719 and using a I₂/I3- electrolyte solution with acetontrile and ethylene carbonate as co-solvent, exhibiting a best efficiency of 6.5%. Meanwhile, the devices based on NP photoanode with the same electrolyte showed an efficiency of 3.44%. Addtionally, the effect of NF films with different thickness on the devices performence was investigated in detail, The optimized thickness of TiO2 NF photoanode was electrospinning for 15min. The improved efficiency was attributed to the increased dye adsorption on TiO2 NF and the improved short-circuit density. The high photovoltaic response of DSSC based on NP/NF double layer were attributed to the surface area(BET: 49.87 m2/g) and volume of NF (0.179 mL/g) of the NF, and the low electron recombination rate. Electrospinning technology provides a new approach for the preparation of large area, the stability and photovoltaic performance of the devices dye-sensitized solar cells and their future commercial applications.