Dual-functional semiconductor-decorated upconversion hollow spheres for high efficiency dye-sensitized solar cellsElectronic supplementary information (ESI) available. See DOI: 10.1039/c5ta06238a

Upconversion/semiconductor submicron hollow spheres composed of inner Na x GdF y O z :Yb/Er shell and outer TiO 2 shell (denoted Na x GdF y O z :Yb/Er@TiO 2 ) were, for the first time, crafted by exploiting colloidal carbon spheres as the scaffold. The hollow spheres were then incorporated into the...

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Hauptverfasser: Liao, Wenming, Zheng, Dajiang, Tian, Jianhua, Lin, Zhiqun
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Sprache:eng
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Zusammenfassung:Upconversion/semiconductor submicron hollow spheres composed of inner Na x GdF y O z :Yb/Er shell and outer TiO 2 shell (denoted Na x GdF y O z :Yb/Er@TiO 2 ) were, for the first time, crafted by exploiting colloidal carbon spheres as the scaffold. The hollow spheres were then incorporated into the TiO 2 nanoparticle film photoanode to yield dye-sensitized solar cells (DSSCs) with improved performance. The implementation of Na x GdF y O z :Yb/Er@TiO 2 hollow spheres in DSSCs imparted the light trapping due to the light scattering from submicron hollow spheres, and the harvesting of near infrared solar photons by the upconversion material ( i.e. , dual functionalities), thereby resulting in an increased short-circuit current density J sc , and thus an improved power conversion efficiency PCE. The electrochemical impedance spectroscopy measurements were performed to scrutinize the interfacial charge transfer characteristics of DSSCs. The measurements revealed that when Na x GdF y O z :Yb/Er hollow spheres without the deposition of TiO 2 shell were integrated in the photoanode, a high charge transfer resistance was found. In stark contrast, the judicious decoration of Na x GdF y O z :Yb/Er hollow spheres with a thin layer of TiO 2 shell markedly improved the contact between the resulting Na x GdF y O z :Yb/Er@TiO 2 shell/shell hollow spheres and the TiO 2 nanoparticle film photoanode, leading to a much decreased charge transfer resistance. Taken together, compared to the PCE of 6.81% for the pristine device, the DSSC assembled with the introduction of 8 wt% Na x GdF y O z :Yb/Er@TiO 2 hollow spheres in the photoanode exhibited an optimal PCE of 7.58% and a maximum short-circuit current density J sc of 18.72 mA cm −2 under AM 1.5G one sun illumination, corresponding to 11.31% performance enhancement. As such, the implementation of upconversion submicron hollow materials in photoanode may stand out as an intriguing strategy to improve the device performance of DSSCs. Upconversion/semiconductor Na x GdF y O z :Yb/Er@TiO 2 hollow spheres were crafted and incorporated into the TiO 2 nanoparticle film photoanode to yield DSSCs with improved performance.
ISSN:2050-7488
2050-7496
DOI:10.1039/c5ta06238a