•  
  •  
 

Corresponding Author

Shu-ming YANG(smyang2006@163.com)

Abstract

The flat band edges (Efb) of nanostructured TiO2 electrodes in electrolyte solutions with tert-butylpyridine (TBP) of different concentrations have been determined with spectroelectrochemical technique. TBP played a role in band energetics of nanostructured TiO2 electrodes. The Efb values of -2.25, -2.46 and -2.62 V were determined in three 0.2 mol•L-1 tetrabutylammonium perchlorate (TBAP) acetonitrile electrolytes which contain 0, 0.2 and 0.4 mol•L-1 TBP respectively. The addition of Li+ ions shifted Efb positively. The Efb values of -1.12, -1.22 and -1.30 V were determined in three 0.2 mol•L-1 LiClO4 acetonitrile electrolytes which contain 0, 0.2 and 0.4 mol•L-1 TBP respectively. The trap state distribution was investigated by the measurements of time resolved current. The total trap state densities of 3.52 × 1016, 3.18 × 1016 and 3.37 × 1016 cm-2 were determined in three 0.2 mol•L-1 TBAP acetonitrile electrolytes which contain 0, 0.2 and 0.4 mol•L-1 TBP respectively with trap distribution maximum located at -1.99, -1.89 and -1.85 V. The addition of Li+ ions further reduced the trap state densities. The total trap state densities of 8.39 × 1015, 1.11 × 1016 and 9.22 × 1015 cm-2 were determined in three 0.2 mol•L-1 LiClO4 acetonitrile electrolytes which contain 0, 0.2 and 0.4 mol•L-1 TBP respectively with trap distribution maximum located at -0.72, -0.84 and -0.95 V. Finally the nanostructured TiO2 electrodes were sensitized with dye N3 and their photoelectrochemical properties were studied in electrolytes with TBP of different concentrations. Experiment results showed that as the concentration of TBP increased, the photoelectric conversion efficiency increased due to improved Voc.

Graphical Abstract

Publication Date

2011-05-28

Online Available Date

2011-05-06

Revised Date

2011-01-06

Received Date

2010-11-18

References

[1] O€™Regan B, Grätzel M. A low-cost, high-efficiency solar cell based on dye-sensitized colloidal TiO2 films [J]. Nature, 1991, 353: 737-740.


[2] Nazeeruddin M K, Péchy P, Renouard T, et al. Engineering of efficient panchromatic sensitizers for nanocrystalline TiO2-based solar cells [J]. J Am Chem Soc, 2001, 123 (8): 1613-1624.


[3] Chiba Y, Islam A, Watanabe Y, et al. Dye-sensitized solar cells with conversion efficiency of 11.1% [J]. Jpn J Appl Phys, 2006, 45 (25): 638-640.


[4] Grätzel M. Photoelectrochemical cells [J]. Nature, 2001, 414: 338-344.


[5] Dai S Y, Weng J, Sui Y F, et al. Dye-sensitized solar cells, from cell to module [J]. Solar Energy Materials and Solar Cells, 2004, 84(1-4): 125-133.


[6] Robertson N. Optimizing dyes for dye-sensitized solar cells [J]. Angew Chem Int Ed, 2006, 45 (15): 2338-2345.


[7] Tian H, Meng F. Solar cells based on cyanine and polymethine dyes. Opt Sci Eng, 2005, 99(4): 313-329.


[8] Grätzel M. The advent of mesoscopic injection solar cells [J]. Prog Photovoltaics: 2006, 14 (5): 429-442.


[9] Bach U, Lupo D, Comte P, et al. Solid state dye sensitized cell showing high photon to current conversion efficiencies [J]. Nature, 1998, 395: 583-585.


[10] Gledhill S E, Scott B, Gregg B A. Organic and nano-structured composite photovoltaics: An overview [J]. J Mater Res, 2005, 20 (12): 3167-3179.


[11] Gorlov M, Kloo L. Ionic liquid electrolytes for dye-sensitized solar cells [J]. Dalton Trans, 2008, 20: 2655-2666.


[12] Chervakov O V, Burmistr M V, Sverdlikovs€™ka O S, et al. Ionic liquids for promising ion-conducting polymer materials of electrochemical devices [J]. Polimernii Zhurnal, 2008, 30 (1): 5-13.


[13] Lenzmann F, Krueger J, Burnside S, et al. Surface Photovoltage Spectroscopy of Dye-Sensitized Solar Cells with TiO2, Nb2O5 and SrTiO3 Nanocrystalline Photoanodes: Indication for Electron Injection from Higher Excited Dye States [J]. J Phys Chem B, 2001, 105 (27): 6347-6352.


[14] Morrison S R. Electrochemistry at Semiconductor and Oxidized Metal Electrodes [M]. New York: Plenum Press, 1980.


[15] Finklea H O. Semiconductor Electrodes [M]. Amsterdam: Elsevier, 1988.


[16] Huang S Y, Schlichthörl G, Nozik A J, et al. Charge recombination in dye-sensitized nanocrystalline TiO2 solar cells [J]. J Phys Chem B, 1997, 101 (14): 2576-2582.


[17] Wang P, Zakeeruddin S M, Exnar I, et al. High efficiency dye-sensitized nanocrystalline solar cells based on ionic liquid polymer gel electrolyte [J]. Chem Commun, 2002, (24): 2972-2973.


[18] Kohle O, Grätzel M, Meyer A F, et al. The photovoltaic stability of bis(isothocyanato) ruthenium(II)-bis-2,2€™-bipyridine-4,4€™-dicarboxylic acid and related sensitizers [J]. Adv Mater, 1997, 9 (11): 904-906.


[19] Kelly C A, Farzad F, Thompson D W, et al. Cation-controlled interfacial charge injection in sensitized nanocrystalline TiO2 [J]. Langmuir, 1999, 15 (20): 7047-7054.


[20] Schlichthorl G, Huang S Y, Sprague J, et al. Band edge movement and recombination kinetics in dye-sensitized nanocrystalline TiO2 solar cells: a study by intensity modulated photovoltage spectroscopy [J]. J Phys Chem B, 1997, 101 (41): 8141-8155.


[21] Liu C, Bard A. A charge-induced absorption-edge shift in cadmium sulfide semiconductor films [J]. J Phys Chem, 1989, 93 (23): 7749-7750.


[22] Redmond G, Fitzmaurice D. Spectroscopic determination of flatband potentials for polycrystalline titania electrodes in nonaqueous solvents [J]. J Phys Chem, 1993, 97 (3): 1426-1430.


[23] Wang H, He J, Boschloo G, et al. Electrochemical investigation of traps in a nanostructured TiO2 Film [J]. J Phys Chem B, 2001, 105 (13): 2529-2533.


[24] Redmond G, Grätzel M, Fitzmaurice D. Effect of surface chelation on the energy of an intraband surface state of a nanocrystalline titania film [J]. J Phys Chem, 1993, 97 (27): 6951-6954.


[25] Enright B, Redmond G, Fitzmaurice D. Spectroscopic determination of flatband potentials for polycrystalline TiO2 electrodes in mixed solvent systems [J]. J Phys Chem, 1994, 98 (24): 6195-6200.


[26] Yang S M, Kou H Z, Wang H J, et al. Preparation and band energetics of transparent nanostructured SrTiO3 film electrodes [J]. J Phys Chem C, 2010, 114 (2): 815-819.


[27] Yang S M, Kou H Z, Wang J C. Tunability of the Band Energetics of Nanostructured SrTiO3 Electrodes for Dye-Sensitized Solar Cells [J]. J Phys Chem C, 2010, 114 (9): 4245-4249.


[28] Nazeeruddin M K, Kay A, Grätzel M. Conversion of light to electricity by cis-X2bis(2,2'-bipyridyl-4,4'-dicarboxylate)ruthenium(II) charge transfer sensitizers (X = Cl-, Br-, I-, CN-, and SCN-) on nanocrystalline titanium dioxide electrodes [J]. J Am. Chem Soc, 1993, 115 (14): 6382-6390.


[29] Ito S, Murakami T N, Comte P, et al. Fabrication of thin film dye sensitized solar cells with solar to electric power conversion efficiency over 10% [J]. Thin Solid Films, 2008, 516 (14): 4613-4619.


[30] Yang S M, Kou H Z, Wang H J, et al. The photoelectrochemical properties of N3 sensitized CaTiO3 modified TiO2 nanocrystalline electrodes [J]. Electrochimica Acta, 2009, 55 (1): 305-310.


[31] Yang S M, Kou H Z, Wang H J, et al. The enhanced photoelectric conversion efficiency of N3 sensitized MgTiO3 modified nanoporous TiO2 electrodes [J]. Colloids Surf A, 2009, 340 (1-3):182-186.


[32] Katoh R, Furube A, Kasuya M, et al. Photoinduced electron injection in black-dye-sensitized nanocrystalline TiO2 films [J]. J Mater Chem, 2007, 17 (30): 3190-3196.


[33] Ooi K, Miyai Y, Sakakihara J. Mechanism of lithium(1+) insertion in spinel-type manganese oxide. Redox and ion-exchange reactions [J]. Lmgmuir, 1991, 7 (6): 1167-1171.


[34] O€™Regan B, Moser J, Anderson M, et al. Vectorial electron injection into transparent semiconductor membranes and electric field effects on the dynamics of light-induced charge separation [J]. J Phys Chem, 1990, 94 (24): 8720-8726.


[35] Yum J H, Nakade S, Kim D Y, et al. Improved performance in dye-sensitized solar cells employing TiO2 photoelectrodes coated with metal hydroxides [J]. J Phys Chem B, 2006, 110 (7): 3215-3219.


[36] Niinobe D, Makari Y, Kitamura T, et al. Origin of enhancement in open-circuit voltage by adding ZnO to nanocrystalline SnO2 in dye-sensitized solar cells [J]. J Phys Chem B, 2005, 109 (38): 17892-17900.


[37] Rosenbluth M L, Lewis N S. €˜Ideal€™ behavior of the open circuit voltage of semiconductor/liquid junctions [J]. J. Phys. Chem, 1989, 93 (9): 3735-3740.

Share

COinS
 
 

To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.