Template-assisted synthesis of porous TiO 2 photoanode for efficient dye-sensitized solar cells
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College of Materials Science and Engineering, Qiqihar University, Qiqihar 161006, China College of Physics and Optoelectronics Engineering, Harbin Engineering University, Harbin 150001, China a)Address all correspondence to this author. e-mail: [email protected] 2
Received: 28 March 2020; accepted: 17 May 2020
As for the efficient dye-sensitized solar cells (DSSCs), one of the important goals is to increase the light harvesting efficiency to further improve the photoelectric conversion efficiency (PCE). The excellent photoanode materials should possess a uniform porous structure, a large surface area, high crystallinity, and good stability. Herein, the porous TiO2 electrode (named as S-1.5) with the above merits had been prepared by the simple template-assisted method with camphene as the pore-forming reagent. The surface area of the porous TiO2 electrode can be tailored by introducing the amount of camphene. The porous TiO2 layer with the optimal surface area directly adhered on the top of the ultra-thin P25 dense layer had been constructed and this unique electrode with a “double layers structure”, which named as S-1.5/P25. When DSSCs assembled with this photoanode, a desirable PCE of 8.31% had been achieved, which was obviously higher than that of the commercial P25 (7.62%) in parallel. The improved PCE can be attributed to the improved utilization of sunlight, the facilitated photo-generated electron transfer, and the reduced interface resistance. Meanwhile, the related characterization including electrochemical impedance spectroscopy, intensity-modulated photovoltage spectroscopy, and intensitymodulated photocurrent spectroscopy was characterized to explore the possible mechanism.
INTRODUCTION Despite the new generation photovoltaic technologies had been developed at the last several years to improve the photovoltaic performance, dye-sensitized solar cells (DSSCs) still received widespread attention from the researchers and industry [1, 2, 3]. In particular, a photoelectric conversion efficiency (PCE) over 28% had been achieved when the DSSCs used in the indoor, where the absorption spectra of the assembled DSSCs can be tuned to match the artificial lighting [4]. Then, the lowcost DSSCs have a great application potential in the near future [5, 6]. For a DSSC, it consisted of a metal oxide semiconductor photoanode, an electrolyte containing the redox couple (I− /I3 − ), and a counter electrode [7, 8]. The photo-generated electron can inject into the conduction band of the metal oxide semiconductor photoanode when the photosensitizer had been excited by the illumination, the dye with the oxidized state can be recovered by the suitable redox couple [9]. Meanwhile, the oxidized shuttles can diffuse to the counter electrode to complete the entire circuit. The main function of
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the photoanode is to load the amount of the photosensitizer and provide a pathway for photo-generated electron transfer to the conductive substrate [10, 11]. The suitable photoanode plays an important
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