Direct assembled metal oxide nanofibrous membranes for futuristic photoanodes in QDs-sensitized Solar Cells
Yong Soo Kang a, Sudhagar Pitchaimuthu a, Juan Bisquert b, Iván Mora-Seró b
a Center for Next Generation Dye-sensitized Solar Cells, WCU Program Department of Energy Engineering, Hanyang University, Seoul 133 791
Oral, Sudhagar Pitchaimuthu, presentation 049
Publication date: 1st April 2013

The photoanode of a QDs-sensitized solar cells (QDSCs) functions as an electron "vehicle" to transport the injected electrons from the excited QDs sensitizers to the outer circuit. In this context, utilization of the wide pore structured, highly interconnected three-dimensional (3-D) fibrous membrane is suitable candidate that rely high charge collection efficiency than the random transport anode architectures. In addition, their architectural advantages for superficial electrolyte penetration through vertical pores yield effective interfacial contacts with anode–sensitizer interfaces. Herein we demonstrate direct assembled 3D fibrous electrodes prepared by an electrospinning technique and the influence of chemical pre-treatment and post-ion treatment on photoconversion efficiency was tested. We found that THF vapor treatment on as-deposited TiO2 fibrous membranes markedly improved the physical adhesion of fibers with the FTO substrate and also enhanced the open-circuit potential from Voc = 0.52 V to Voc = 0.57 V due to a reduction in the recombination rate. F-ion post-treatment on the TiO2 fibrous membrane improves both Voc (0.61 V) and Jsc (11.4 mA cm-2) of the device with an overall efficiency of 2.8%. Concurrently, further Voc enhancement is observed after ZnS coating on a sensitizer layer (QDs), which strikingly improves the Voc (0.69 V) by passivating the QDs. With the combined THF–F ion treatment with the ZnS passivation layer on the QD-sensitizer, our proposed TiO2 fibrous photoanode yielded a device performance of 3.2% with a remarkable Voc = 0.69 V compared with most of the reports existing in the literature. In addition to the surface treatment approach, we applied fibrous membranes as backbone membranes for designing 3D- hierarchical nanotube branched photoanodes. We compare the photoelectron conversion performance of directly grown nanotube on conducting substrates (TiO2-NT) and fibrous backbone membranes (H-TiO2-NFs). The hierarchical 3-D photoanodes (H-TiO2-NFs) demonstrate excellent candidature as photoanodes in QD-sensitized solar cells, exhibiting 3-fold higher energy conversion efficiency (η = 2.8%, Jsc = 8.8 mA cm-2) than that of the directly grown nanotube arrays on a transparent conducting oxide (TCO) substrate (η = 0.9%, Jsc = 2.5 mA cm-2). The beneficial merits of 3D-fibrous backbone membranes result (a) higher effective surface area and consequently higher QD loading and light harvesting; (b) highly efficient charge collection throughout the photoanode with fewer boundary layers and (c) the multiple scattering effect of the comb-like hierarchical NT arrays, are fostering fibrous membranes are futuristic photoanodes in QDs-sensitized solar cells.



Han, H.; Sudhagar, P; Song, T; , Jeon, Y; Seró, I-M; Santiago, F-F; Bisquert, J; Kang, Y-S; Paik, U;. Three dimensional-TiO2 nanotube array photoanode architectures assembled on a thin hollow nanofibrous backbone and their performance in quantum dot-sensitized solar cells. Chem. Commun. 2013, 49, 2810-2812.

Sudhagar, P; Pedro, V-G; Seró, I-M; Santiago, F-F; Bisquert, J; Kang, Y-S. Interfacial Engineering of Quantum Dot-Sensitized TiO2 Fibrous Electrodes for Futuristic Photoanodes in Photovoltaic Applications. Journal of Materials Chemistry 2012, 22, 14228.

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