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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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 |