Effect of annealing on the sub-bandgap, defects and trapping states of ZnO nanostructures
| Autor: | Jonathan Plentz, Martin Presselt, Ruri Agung Wahyuono, Felix Hermann-Westendorf, Jan Dellith, Benjamin Dietzek, Martin Seyring, Martin Schulz, Christa Schmidt, Markus Rettenmeyer, Andrea Dellith |
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| Rok vydání: | 2017 |
| Předmět: |
Photoluminescence
Nanostructure business.industry Annealing (metallurgy) Chemistry Band gap Energy conversion efficiency General Physics and Astronomy Nanotechnology 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences 0104 chemical sciences Dye-sensitized solar cell Optoelectronics Nanorod Physical and Theoretical Chemistry 0210 nano-technology Luminescence business |
| Zdroj: | Chemical Physics. :112-121 |
| ISSN: | 0301-0104 |
| Popis: | Annealing treatment was applied to different mesoporous ZnO nanostructures prepared by wet chemical synthesis, i.e. nanoflowers (NFs), spherical aggregates (SPs), and nanorods (NRs). The sub-bandgap, defect properties as well as the trapping state characteristics after annealing were characterized spectroscopically, including ultrasensitive photothermal deflection spectroscopy (PDS), photoluminescence and photo-electrochemical methods. The comprehensive experimental analysis reveals that annealing alters both the bandgap and the sub-bandgap. The defect concentration and the density of surface traps in the ZnO nanostructures are suppressed upon annealing as deduced from photoluminescence and open-circuit voltage decay analysis. The photo-electrochemical investigations reveal that the surface traps dominate the near conduction band edge of ZnO and, hence, lead to high recombination rates when used in DSSCs. The density of bulk traps in ZnO SPs is higher than that in ZnO NFs and ZnO NRs and promote lower recombination loss between photoinjected electrons with the electrolyte-oxidized species on the surface. The highest power conversion efficiency of ZnO NFs-, ZnO SPs-, and ZnO NRs-based DSSC obtained in our system is 2.0, 4.5, and 1.8%, respectively. |
| Databáze: | OpenAIRE |
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