1. School of Chemical Engineering and Technology, Tianjin University, Tianjin 300350, China 2. Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300350, China
Three-dimensional TiO2 microspheres doped with N were synthesized by a simple single-step solvothermal method and the sample treated for 15 h (hereafter called TMF) was then used as scattering layers in the photoanodes of dye-sensitized solar cells (DSSCs). The TMF was characterized using scanning electron microscopy, high resolution transmission electron microscopy, Brunauer-Emmett-Teller measurements, X-ray diffraction, and X-ray photoelectron spectroscopy. The TMF had a high surface area of 93.2 m2·g−1 which was beneficial for more dye-loading. Five photoanode films with different internal structures were fabricated by printing different numbers of TMF scattering layers on fluorine-doped tin oxide glass. UV-vis diffuse reflection spectra, incident photon-to-current efficiencies, photocurrent-voltage curves and electrochemical impedance spectroscopy were used to investigate the optical and electrochemical properties of these photoanodes in DSSCs. The presence of nitrogen in the TMF changed the TMF microstructure, which led to a higher open circuit voltage and a longer electron lifetime. In addition, the presence of the nitrogen significantly improved the light utilization and photocurrent. The highest photoelectric conversion efficiency achieved was 8.08%, which is much higher than that derived from typical P25 nanoparticles (6.52%).
O’Regan B, Grätzel M. A low-cost, high-efficiency solar cell based on dye-sensitized colloidal TiO2 films. Nature, 1991, 353(6346): 737–740 https://doi.org/10.1038/353737a0
Hagfeldt A, Boschloo G, Sun L, Kloo L, Pettersson H. Dye-sensitized solar cells. Chemical Reviews, 2010, 110(11): 6595–6663 https://doi.org/10.1021/cr900356p
4
Yella A, Lee H, Tsao H, Yi C, Chandiran A, Nazeeruddin M, Diau E, Yeh C, Zakeeruddin S, Grätzel M. Porphyrin-sensitized solar cells with cobalt (II/III)-based redox electrolyte exceed 12 percent efficiency. Science, 2011, 334(6056): 629–634 https://doi.org/10.1126/science.1209688
5
Chen W, Qiu Y, Yang S. A new ZnO nanotetrapods/SnO2 nanoparticles composite photoanode for high efficiency flexible dye-sensitized solar cells. Physical Chemistry Chemical Physics, 2010, 12(32): 9494–9501 https://doi.org/10.1039/c000584c
6
Chen X, Mao S. Titanium dioxide nanomaterials: Synthesis, properties, modifications, and applications. Chemical Reviews, 2007, 107(7): 2891–2959 https://doi.org/10.1021/cr0500535
7
Tao X, Wang Y, Zhang X, Sun H, Zhang Q, Niu L, Liu J, Zhou X. Visible-light wavelength matched microsphere assembly of TiO2 superfine nanorods and the enhanced photovoltaic performance. Journal of Alloys and Compounds, 2015, 631: 202–208 https://doi.org/10.1016/j.jallcom.2015.01.079
8
Ke W, Fang G, Tao H, Qin P, Wang J, Lei H, Liu Q, Zhao X. In situ synthesis of NiS nanowall networks on Ni foam as a TCO-free counter electrode for dye-sensitized solar cells. ACS Applied Materials & Interfaces, 2014, 6(8): 5525–5530 https://doi.org/10.1021/am4059155
9
Liu Y, Wang S, Shan Z, Li X, Tian J, Mei Y, Ma H, Zhu K. Anatase TiO2 hollow spheres with small dimension fabricated via a simple preparation method for dye-sensitized solar cells with an ionic liquid electrolyte. Electrochimica Acta, 2012, 60: 422–427 https://doi.org/10.1016/j.electacta.2011.11.088
10
Ding Y, Xia X, Chen W, Hu L, Mo L, Huang Y, Dai S. Inside-out Ostwald ripening: A facile process towards synthesizing anatase TiO2. Nano Research, 2016, 9(7): 1891–1903 https://doi.org/10.1007/s12274-016-1081-2
11
Haid S, Marszalek M, Mishra A, Wielopolski M, Teuscher J, Moser J, Humphry-Baker R, Zakeeruddin S, Grätzel M, Bäuerle P. Significant improvement of dye-sensitized solar cell performance by small structural modification in π-conjugated donor-acceptor dyes. Advanced Functional Materials, 2012, 22(6): 1291–1302 https://doi.org/10.1002/adfm.201102519
12
Bach U, Daeneke T. A solid advancement for dye-sensitized solar cells. Angewandte Chemie International Edition, 2012, 51(42): 10451–10452 https://doi.org/10.1002/anie.201205437
13
Gao Y, Feng Y, Zhang B, Zhang F, Peng X, Liu L, Meng S. Double-N doping: A new discovery about N-doped TiO2 applied in dye-sensitized solar cells. RSC Advances, 2014, 4(33): 16992–16998 https://doi.org/10.1039/C4RA00053F
14
Zhang Z, Cui Z, Zhang K, Feng Y, Meng S. Samarium ions doped titania photoelectrodes for efficiency influence of dye-sensitized solar cells. Journal of the Electrochemical Society, 2016, 163(5): A644–A649 https://doi.org/10.1149/2.0371605jes
15
Cahen D, Hodes G, Grätzel M, Guillemoles J, Riess I. Nature of photovoltaic action in dye-sensitized solar cells. Journal of Physical Chemistry B, 2000, 104(9): 2053–2059 https://doi.org/10.1021/jp993187t
16
Pan H, Qian J, Cui Y, Xie H, Zhou X. Hollow anatase TiO2 porous microspheres with V-shaped channels and exposed (101) facets: Anisotropic etching and photovoltaic properties. Journal of Materials Chemistry, 2012, 22(13): 6002–6009 https://doi.org/10.1039/c2jm15925b
17
He X, Li X, Zhu M. The application of hollow box TiO2 as scattering centers in dye-sensitized solar cells. Journal of Power Sources, 2016, 333: 10–16 https://doi.org/10.1016/j.jpowsour.2016.09.133
18
Bakhshayesh A, Azadfar S. Orderly decorated nanostructural photoelectrodes with uniform spherical TiO2 particles for dye-sensitized solar cells. Frontiers of Chemical Science and Engineering, 2015, 9(4): 532–540 https://doi.org/10.1007/s11705-015-1549-8
19
Li W, Yang J, Jiang Q, Luo Y, Hou Y, Zhou S, Zhou Z. Bi-layer of nanorods and three-dimensional hierarchical structure of TiO2 for high efficiency dye-sensitized solar cells. Journal of Power Sources, 2015, 284: 428–434 https://doi.org/10.1016/j.jpowsour.2015.03.046
20
Kim D, Kim J, Shin S, Cho J, Cho I. Facile one-pot synthesis of self-assembled quantum-rod TiO2 spheres with enhanced charge transport properties for dye-sensitized solar cells and solar water-splitting. Journal of Alloys and Compounds, 2017, 697: 222–230 https://doi.org/10.1016/j.jallcom.2016.12.112
21
Wang G, Zhu X, Yu J. Bilayer hollow/spindle-like anatase TiO2 photoanode for high efficiency dye-sensitized solar cells. Journal of Power Sources, 2015, 278: 344–351 https://doi.org/10.1016/j.jpowsour.2014.12.091
22
Zhao P, Yao S, Wang M, Wang B, Sun P, Liu F, Liang X, Sun Y, Lu G. High-efficiency dye-sensitized solar cells with hierarchical structures titanium dioxide to transfer photogenerated charge. Electrochimica Acta, 2015, 170: 276–283 https://doi.org/10.1016/j.electacta.2015.04.102
23
Sun X, Zhou X, Xu Y, Sun P, Huang N, Sun Y. Mixed P25 nanoparticles and large rutile particles as a top scattering layer to enhance performance of nanocrystalline TiO2 based dye-sensitized solar cells. Applied Surface Science, 2015, 337: 188–194 https://doi.org/10.1016/j.apsusc.2015.02.090
24
Ding Y, Mo L, Tao L, Ma Y, Hu L, Huang Y, Fang X, Yao J, Xi X, Dai S. TiO2 nanocrystalline layer as a bridge linking TiO2 sub-microspheres layer and substrates for high-efficiency dye-sensitized solar cells. Journal of Power Sources, 2014, 272: 1046–1052 https://doi.org/10.1016/j.jpowsour.2014.09.007
25
Yan K, Qiu Y, Chen W, Zhang M, Yang S. A double layered photoanode made of highly crystalline TiO2 nanooctahedra and agglutinated mesoporous TiO2 microspheres for high efficiency dye sensitized solar cells. Energy & Environmental Science, 2011, 4(6): 2168–2176 https://doi.org/10.1039/c1ee01071a
26
Chen D, Huang F, Cheng Y, Caruso R. Mesoporous anatase TiO2 beads with high surface areas and controllable pore sizes: A superior candidate for high-performance dye-sensitized solar cells. Advanced Materials, 2009, 21(21): 2206–2210 https://doi.org/10.1002/adma.200802603
27
Kim Y, Lee M, Kim H, Lim G, Choi Y, Park N, Kim K, Lee W. Formation of highly efficient dye-sensitized solar cells by hierarchical pore generation with nanoporous TiO2 spheres. Advanced Materials, 2009, 21(36): 3668–3673 https://doi.org/10.1002/adma.200900294
28
Son S, Hwang S, Kim C, Yun J, Jang J. Designed, synthesis of SiO2/TiO2 core/shell structure as light scattering material for highly efficient dye-sensitized solar cells. ACS Applied Materials & Interfaces, 2013, 5(11): 4815–4820 https://doi.org/10.1021/am400441v
29
Xiong Y, He D, Jin Y, Cameron P, Edler K. Ordered mesoporous particles in titania films with hierarchical structure as scattering layers in dye-sensitized solar cells. Journal of Physical Chemistry C, 2015, 119(39): 22552–22559 https://doi.org/10.1021/acs.jpcc.5b06977
30
Hwang D, Sung S. Controlled fabrication of mesoporous TiO2 hierarchical structures as scattering layers to enhance the power conversion efficiency of dye-sensitized solar cells. Physical Chemistry Chemical Physics, 2016, 18(44): 30254–30260 https://doi.org/10.1039/C6CP05999F
Peng X, Feng Y, Meng S, Zhang B. Preparation of hierarchical TiO2 films with uniformly or gradually changed pore size for use as photoelectrodes in dye-sensitized solar cells. Electrochimica Acta, 2014, 115: 255–262 https://doi.org/10.1016/j.electacta.2013.10.126
33
Liu M, Piao L, Zhao L, Ju S, Yan Z, He T, Zhou C, Wang W. Anatase TiO2 single crystals with exposed {001} and {110} facets: Facile synthesis and enhanced photocatalysis. Chemical Communications, 2010, 46(10): 1664–1666 https://doi.org/10.1039/b924172h
34
Lin J, Zhao L, Heo Y, Wang L, Bijarbooneh F, Mozer A, Nattestad A, Yamauchi Y, Dou S, Kim J. Mesoporous anatase single crystals for efficient Co(2+/3+)-based dye-sensitized solar cells. Nano Energy, 2015, 11: 557–567 https://doi.org/10.1016/j.nanoen.2014.11.017
35
Zhang Y, Zhang B, Peng X, Liu L, Dong S, Lin L, Chen S, Meng S, Feng Y. Preparation of dye sensitized solar cells with high photocurrent and photovoltage by using mesoporous TiO2 particles as photoanode material. Nano Research, 2015, 8(12): 3830–3841 https://doi.org/10.1007/s12274-015-0883-y
36
Biswas S, Hossain M, Takahashi T. Fabrication of Grätzel solar cell with TiO2/CdS bilayered photoelectrode. Thin Solid Films, 2008, 517(3): 1284–1288 https://doi.org/10.1016/j.tsf.2008.06.010
37
Sing K S W. Reporting physisorption data for gas/solid systems with special reference to the determination of surface area and porosity (Recommendations 1984). Pure and Applied Chemistry, 1985, 57(4): 603–619 https://doi.org/10.1351/pac198557040603
38
Ramasamy E, Lee J. Ordered mesoporous Zn-doped SnO2 synthesized by exotemplating for efficient dye-sensitized solar cells. Energy & Environmental Science, 2011, 4(7): 2529–2536 https://doi.org/10.1039/c1ee01123e
39
Guo W, Shen Y, Wu L, Gao Y, Ma T. Effect of N dopant amount on the performance of dye-sensitized solar cells based on N-doped TiO2 electrodes. Journal of Physical Chemistry C, 2011, 115(43): 21494–21499 https://doi.org/10.1021/jp2057496
Fu Y, Du H, Zhang S, Huang W. XPS characterization of surface and interfacial structure of sputtered TiNi films on Si substrate. Materials Science and Engineering A, 2005, 403(1): 25–31 https://doi.org/10.1016/j.msea.2005.04.036
42
Huo K, Wang H, Zhang X, Cao Y, Chu P. Heterostructured TiO2 nanoparticles/nanotube arrays: In situ formation from amorphous TiO2 nanotube arrays in water and enhanced photocatalytic activity. ChemPlusChem, 2012, 77(4): 323–329 https://doi.org/10.1002/cplu.201200024
43
Yu I, Kim Y, Kim H, Lee C, Lee W. Size-dependent light-scattering effects of nanoporous TiO2 spheres in dye-sensitized solar cells. Journal of Materials Chemistry, 2011, 21(2): 532–538 https://doi.org/10.1039/C0JM02606A
44
Xu J, Wang G, Fan J, Liu B, Cao S, Yu J. g-C3N4 modified TiO2 nanosheets with enhanced photoelectric conversion efficiency in dye-sensitized solar cells. Journal of Power Sources, 2015, 274: 77–84 https://doi.org/10.1016/j.jpowsour.2014.10.033
45
Park N, van de Lagemaat J, Frank A. Comparison of dye-sensitized rutile-and anatase-based TiO2 solar cells. Journal of Physical Chemistry B, 2000, 104(38): 8989–8994 https://doi.org/10.1021/jp994365l
46
Kang T, Chun K, Hong J, Moon S, Kim K. Enhanced stability of photocurrent-voltage curves in Ru(II)-dye-sensitized nanocrystalline TiO2 electrodes with carboxylic acids. Journal of the Electrochemical Society, 2000, 147(8): 3049–3053 https://doi.org/10.1149/1.1393646
47
Tian H, Hu L, Zhang C, Liu W, Huang Y, Mo L, Guo L, Sheng J, Dai S. Retarded charge recombination in dye-sensitized nitrogen-doped TiO2 solar cells. Journal of Physical Chemistry C, 2010, 114(3): 1627–1632 https://doi.org/10.1021/jp9103646
48
Chang H, Lo Y. Pomegranate leaves and mulberry fruit as natural sensitizers for dye-sensitized solar cells. Solar Energy, 2010, 84(10): 1833–1837 https://doi.org/10.1016/j.solener.2010.07.009
49
Dai G, Zhao L, Li J, Wan L, Hu F, Xu Z, Dong B, Lu H, Wang S, Yu J. A novel photoanode architecture of dye-sensitized solar cells based on TiO2 hollow sphere/nanorod array double-layer film. Journal of Colloid and Interface Science, 2012, 365(1): 46–52 https://doi.org/10.1016/j.jcis.2011.08.073
50
Yang J, Gao Z, Tian L, Ma P, Wu D, Yang L. Spindle-like TiO2 with high crystallinity and its application in dye sensitised solar cell. Micro & Nano Letters, 2011, 6(8): 737–740 https://doi.org/10.1049/mnl.2011.0317
51
Liu W, Liang Z, Kou D, Hu L, Dai S. Wide frequency range diagnostic impedance behavior of the multiple interfaces charge transport and transfer processes in dye-sensitized solar cells. Electrochimica Acta, 2013, 88: 395–403 https://doi.org/10.1016/j.electacta.2012.10.061
52
Nakade S, Saito Y, Kubo W, Kitamura T, Wada Y, Yanagida S. Influence of TiO2 nanoparticle size on electron diffusion and Recombination in dye-sensitized TiO2 solar cells. Journal of Physical Chemistry B, 2003, 107(33): 8607–8611 https://doi.org/10.1021/jp034773w
53
Liao J, Lei B, Kuang D, Su C. Tri-functional hierarchical TiO2 spheres consisting of anatase nanorods and nanoparticles for high efficiency dye-sensitized solar cells. Energy & Environmental Science, 2011, 4(10): 4079–4085 https://doi.org/10.1039/c1ee01574e