Photocharging and Band Gap Narrowing Effects on the Performance of Plasmonic Photoelectrodes in Dye-Sensitized Solar Cells
Por:
Villanueva-Cab, Julio, Olalde-Velasco, Paul, Romero-Contreras, Alfredo, Zhuo, Zengqing, Pan, Feng, Rodil, Sandra E., Yang, Wanli, Pal, Umapada
Publicada:
19 sep 2018
Resumen:
The incorporation of plasmonic nanostructures in active electrodes has
become one of the most attractive ways to enhance the photoconversion
efficiency (PCE) of dye-sensitized solar cells (DSSCs). Although an
enhancement of PCE because of the incorporation of plasmonic
nanostructures of different sizes, either bare or coated, has been
demonstrated, the fundamental mechanisms associated to such enhancement
are still unclear. Besides, the photocurrent enhancement of plasmonic
DSSCs is frequently associated to the strong surface plasmon resonance
(SPR) absorption of metal nanoparticles. In this work, through oxygen
K-edge soft X-ray absorption and emission spectroscopies of plasmonic
electrodes and electrodynamical characterization of the fabricated
cells, we demonstrate a band gap narrowing and photocharging effect on
the plasmonic electrodes that definitely contribute to the PCE
enhancement in plasmonic DSSCs. The incorporation of bare metal
nanoparticles in active metal oxide semiconductor electrodes such as
TiO2 in optimum concentration causes an upward shift of its valence band
edge, reducing its effective band gap energy and enhancing the
short-circuit current of DSSCs. On the other hand, small
perturbation-based stepped light-induced transient measurements of
photovoltage and photocurrent of the operating DSSCs revealed an upward
shift of quasi-Fermi level of photoelectrodes because of the
photocharging effect induced by the incorporated metal nanoparticles.
The upward shift of the quasi-Fermi level causes an increase in
open-circuit voltage (V-OC), nullifying the effect of band gap
reduction. The short-circuit photocurrent enhancement was controlled by
the band gap narrowing, screening the SPR contribution. The results
presented in this work not only clarify the contribution of SPR
absorption in plasmonic DSSCs, but also highlight the importance of
considering the corrections in the effective base voltage because of the
quasi-Fermi level band shift during the estimation of the transport and
recombination parameters of an assembled DSSC.
Filiaciones:
Villanueva-Cab, Julio:
Benemerita Univ Autonoma Puebla, Inst Fis, Apdo Postal J-48, Puebla 72570, Puebla, Mexico
Olalde-Velasco, Paul:
Benemerita Univ Autonoma Puebla, Inst Fis, Apdo Postal J-48, Puebla 72570, Puebla, Mexico
Romero-Contreras, Alfredo:
Benemerita Univ Autonoma Puebla, Inst Fis, Apdo Postal J-48, Puebla 72570, Puebla, Mexico
Zhuo, Zengqing:
Lawrence Berkeley Natl Lab, Adv Light Source, 1 Cyclotron Rd, Berkeley, CA 94720 USA
Peking Univ, Sch Adv Mat, Shenzhen Grad Sch, Shenzhen 518055, Peoples R China
Pan, Feng:
Peking Univ, Sch Adv Mat, Shenzhen Grad Sch, Shenzhen 518055, Peoples R China
Rodil, Sandra E.:
Univ Nacl Autonoma Mexico, Inst Invest Mat, Mexico City 04510, DF, Mexico
Yang, Wanli:
Lawrence Berkeley Natl Lab, Adv Light Source, 1 Cyclotron Rd, Berkeley, CA 94720 USA
Pal, Umapada:
Benemerita Univ Autonoma Puebla, Inst Fis, Apdo Postal J-48, Puebla 72570, Puebla, Mexico
|