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Titanium dioxide broccoli for solar cells

Titanium dioxide (TiO2) is one of the most important oxides; it has been widely investigated due to its high dielectric constant, humidity and oxygen sensitivities and photoelectric and catalytic conversion properties [1–3], excellent electronic, magnetic, optical, and mechanical properties [4–7] and hence it has numerous applications in photovoltaic cells or dye and quantum dot sensitized solar cells (DSSC, QDSSC), photocatalysis, Li-ion battery materials, sensors, etc: mainly due to its wide-band-gap semiconductor properties [8–11].

DSSC, using nanocrystalline TiO2 as photoanode material, has captured more and more attention because of the low cost of the material and its fabrication, and it is regarded as one of the most promising alternatives to the commercial silicon based solar cells presently available. The photoanode material has been found to play an important role in the photovoltaic performance of a DSSC since it influences the dye loading, light scattering and electron transport. Remarkable achievements have been made by using TiO2 photoelectrode with various morphologies such as nanoparticles, sub-micro-spheres, beads, one-dimensional (1D) or quasi-1D nanoarrays such as nanorods/wires and nanotubes. These 1D structures can be recognized as effective pathways for the facilitation of electron transport and minimization of the recombination rate, resulting in an improvement of the charge collection efficiency.

Present work demonstrates the synthesis of titanium dioxide cauliflower-like nanostructures possessing high surface area and hierarchical nonstructural formation leading to effective light harvesting which can be further exploited as a photoanodes for the DSSC. Herein, we report on the chemical synthesis of TiO2 broccoli using a facile and low cost hydrothermal method without any catalysts or templates for preparing rutile TiO2 crystals merely by adjusting the amount of titanium tetrachloride precursor amounts.

The photoelectrochemical activities are found to be dependent on the morphology of the photoanodes; therefore morphology control of TiO2 is supposed to be an effective way to improve the photoelectrochemical performance. Hierarchical architectures have attracted more and more researchers in recent years, compared to nanoparticles, due their high surface-to-volume ratio, high organic pollutant adsorption, and excellent incident light scattering within the structures. Nowadays, efforts are focused on the investigation of hierarchical architectures instead of conventional nanoparticles for further enhancement of the photoelectrochemical performance of TiO2.

The material shown on this cover of Nano Today was synthesized at Thin Film Materials Laboratory, Department of Physics, Shivaji University, Kolhapur, Maharashtra, INDIA. It resulted from a Ph. D. work of Mr. Sachin A. Pawar under the supervision of Prof. Pramod S. Patil. The TiO2 produced has used as photoanode for Quantum dot sensitized solar cells application.


The financial support from UGC-SAP-DSA-I, New Delhi and Department of Science and Technology (DST) INDIA through DST FIST-II and DST-PURSE scheme is acknowledged. This work is partially supported by the Human Resource Development of the Korea Institute of Energy technology Evaluation and Planning (KETEP) grant funded by the Korea Government Ministry of knowledge Economy (No. 20124010203180). Dr. Rupesh S. Devan and Prof. Yuan R. Ma from National Dong Hwa University, Taiwan are acknowledged for assistance with FE-SEM/EDS/XPS analyses.

Corresponding Authors Emails: (Prof. Pramod S. Patil), (Mr. Sachin A. Pawar).

Co-corresponding Author Email: (Prof. Jin-Hyeok Kim).

Further reading:

[1] R.S. Devan, R. A. Patil, J. H. Lin, Y.R. Ma, Advanced Functional Materials 22 (2012) 3326.; [2] J.E.G.J. Wijnhiven, W.L. Vos, Science 281 (1998) 802.; [3] J. Tang, H. Quan, J. Ye, Chemistry of Materials 19 (2007) 116.; [4] H. Xu, P. Reunchan, S. Ouyang, H. Tong, N. Umezawa, T. Kako, J. Ye, Chemistry of Materials 25 (2013) 405.; [5] Y. Ren, M. Chen, Y. Zhang, L. Wu, Langmuir 26 (2010) 11391.; [6] H.P. Deshmukh, P.S. Shinde, P.S. Patil, Materials Science and Engineering B 130 (2006) 220.; [7] L. C. Chuanga, C., Hsiang, L. S. Yang, Applied Surface Science, 258 (2011) 297.; [8] A. Hagfeldt, G. Boschloo, L. Sun, L. Kloo, H. Pettersson, Chemical Reviews 110 (2010) 6595.; [9] B.L. Sypiena, A. Czapla, M. Lubecka, P. Gwizdz, K. Schneider, K. Zakrzewska, K. Michalow, T. Graule, A. Reszka, M. Rekas, A. Lacz, Sensors and Actuators B 175 (2012) 163.; [10] A. Fujishima, K. Honda, Nature 238 (1972) 37.; [11] A. L. Linsebigler, G.Q. Lu, J.T. Yates, Chemical Reviews 95 (1995) 735.