Enhanced photovoltaic conversion efficiency of a dye-sensitized solar cell based on TiO 2 nanoparticle/nanorod array com
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INTERCONNECTS AND INTERFACES IN ENERGY CONVERSION MATERIALS
Enhanced photovoltaic conversion efficiency of a dyesensitized solar cell based on TiO2 nanoparticle/nanorod array composites Chengtao Yu1,a)
, Jingyi Zhang1, Hexu Yang1, Ling Zhang1, Yu Gao1
1
School of Mechanical Engineering, Ningxia Institute of Science and Technology, Shizuishan 753000, China Address all correspondence to this author. e-mail: [email protected]
a)
Received: 24 August 2018; accepted: 10 October 2018
Hierarchical nanostructure of TiO2 nanoparticles/nanorod arrays (TiO2 NPs/NRs) is synthesized and applied in dye-sensitized solar cells (DSSCs) comparing with the TiO2 nanorod (TiO2 NR) arrays and the TiO2 nanoparticles (TiO2 NPs). The TiO2 NP/NR surface morphology is revealed by X-ray diffraction, field emission scanning, and transmission electron microscopy. The power conversion efficiency of NP/NR-based DSSCs (length 3 lm) is improved to 3.47%, which is 2.2 times higher than the NR-based DSSCs (length 3 lm), and rivals the NP-based DSSC (length 5 lm). The high photovoltaic performance was attributed to that the TiO2 NP/NR photoanode has large surface area and exhibits excellent light scattering, allowing for fast interfacial charge transfer and less charge recombination, which are characterized using the UV-vis absorbance spectra, Brunauer–Emmett–Teller (BET) surface area, electrochemical impedance spectroscopy (EIS) measurements, and photoluminescence (PL) spectroscopy. However, further work is needed to overcome the limitations of TiO2 NP/NR and improve the performance of TiO2 NP/NR-based DSSC.
Introduction TiO2 is one of the most prominent material known in performing various kinds of functions in many areas including photocatalytic water splitting for hydrogen production [1, 2], organic pollutant degradation [3, 4], photovoltaic cells [5, 6], lithium-ion battery [7, 8], and supercapacitors [9]. TiO2 is the most preferred photoanode used in dye-sensitized solar cells (DSSCs) [10, 11]. Since the pioneering work of O’Regan and Grätzel in 1991, the DSSCs have attracted extensive attention from both scientific and technological aspects because of their intrinsic advantages of easy production, nonpolluting, low cost, and relatively high-power conversion efficiency (g) [12, 13, 14]. Typically, the photoanode of a DSSC is made of a TiO2 nanoparticle (NP) mesoporous film on transparent conductive oxide glass, and a monolayer of a ruthenium-based complex dye is usually absorbed to its surface. Up to now, photoanodes in high-performance devices are composed of nanoporous anatase TiO2 NPs because of their large surface area [15, 16]. However, there are numerous grain boundaries in TiO2 NPs, which limit the g of DSSCs. Their performance is impaired by
ª Materials Research Society 2019
poor electron transport, too many surface traps, repeated charge recombination, and low light scattering capabilities [17, 18]. To overcome this limitation, recent researches have been directed toward the use of one-dimensional (1D) TiO2 nanostructures
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