Nanophotonics and Advanced Materials Group

León, Mexico

Nanophotonics and Advanced Materials Group

León, Mexico
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Esparza D.,Nanophotonics and Advanced Materials Group | Esparza D.,Autonomous University of Zacatecas | Lopez-Luke T.,Nanophotonics and Advanced Materials Group | Oliva J.,Autonomous University of Coahuila | And 4 more authors.
Electrochimica Acta | Year: 2017

In this work, we demonstrate an enhancement of photocurrent in QDSSCs based on CdS (QDs)/CdSe Quantum rods (QRs)/CdSeTe (QDs) heterostructure due to the increased photon harvesting in the VIS-NIR region. The photo-conversion efficiency increased from 2.7% up to 6.5% when CdSe QRs and CdSeTe QDs were added in the reference cell: TiO2/CdS/ZnS and the devices reached a maximum photocurrent of 21.5 mA cm−2. This outstanding performance was caused by a broadening of the light absorption in the VIS and NIR regions, this in turn, was produced by the presence of CdSe QRs and CdSeTe QDs in the cells. The use of additional SiO2 layer in the solar cell that contained CdSe QRs and CdSeTe QDs allowed us to improve the efficiency of the cells even more (up to 7.4%), since it decreased the recombination rate produced by defects and interfaces in the QDs. Moreover, the effect on the solar cells performance was studied as the size of the CdSeTe QDs introduced into them increases and found that both, the values of photocurrent and efficiency are enhanced as the size of the CdSeTe increases. We associated this improvement of performance to the increase of light absorption in the NIR region as the size of the CdSeTe QDs increases. Hence, our results suggest that the strategy of adding CdSeTe QDs with different sizes together with CdSe QRs is promising to enhance the efficiency of QDSSCs. © 2017


Esparza D.,Nanophotonics and Advanced Materials Group | Zarazua I.,Nanophotonics and Advanced Materials Group | Lopez-Luke T.,Nanophotonics and Advanced Materials Group | Cerdan-Pasaran A.,Nanophotonics and Advanced Materials Group | And 5 more authors.
Journal of Physical Chemistry C | Year: 2015

The procedure employed for the sensitization of mesoporous photoanodes affects strongly the final performance of sensitized devices, especially when semiconductor quantum dots and quantum rods are used as sensitizers. In this work the effect of three different sensitizing methods in the final cell performance was analyzed. The TiO2 films were sensitized with CdS QDs grown by successive ionic layer adsorption and reaction, SILAR, and with CdSe quantum rods deposited by electrophoretic and pipetting methods. Several configurations of the sensitizers and combinations of sensitization methods were tested. 4% photoconversion efficiencies were obtained for TiO2 electrodes sensitized with CdS and CdSe by electrophoretic and pipetting respectively, while for the sensitizer with both techniques the efficiency was 4.7%. This high efficiency is mainly due to the high fill factor (60%) and the photocurrents (13.1 mA/cm2) obtained by the correct combination of near-infrared and visible light photoabsorption, the better CdSe QRs distribution in the TiO2 film and a passivation of the TiO2 nanocrystals. Electrochemical impedance measurements has been analyzed and discussed in detail providing a detailed analysis of recombination resistance and charge transport processes. These parameters have been correlated with the cell performance. © 2015 American Chemical Society.

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