Enhanced photovoltaic conversion efficiency of a dye-sensitized solar cell based on TiO2 nanoparticle/nanorod array composites

Hierarchical nanostructure of TiO2nanoparticles/nanorod arrays (TiO2NPs/NRs) is synthesized and applied in dye-sensitized solar cells (DSSCs) comparing with the TiO2nanorod (TiO2NR) arrays and the TiO2nanoparticles (TiO2NPs). The TiO2NP/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 µm) is improved to 3.47%, which is 2.2 times higher than the NR-based DSSCs (length 3 µm), and rivals the NP-based DSSC (length 5 µm). The high photovoltaic performance was attributed to that the TiO2NP/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 TiO2NP/NR and improve the performance of TiO2NP/NR-based DSSC.