Abstracts Book - IMRC 2018

• SC4-P033
SOLAR CELL EFFICIENCY IMPROVEMENT EMPLOYING
PHOTOLUMINESCENT SI AND ZNO QD MULTILAYERED FILMS
Alejandra Cordova Rubio 1 , Rosendo Lopez Delgado 2 , Aldo Zazueta Raynaud 1 , Arturo Ayon 2 ,
Mario Enrique Alvarez Ramos 1
1
Universidad de Sonora, Departamento de fisica, Mexico. 2 The University of Texas at San
Antonio, Department of Physics and Astronomy, United States.
In recent years, solar cells have typically been made of silicon because the
efficiency that these photovoltaic devices present is relatively high. However, it
has some limitations in the range of energies of photon absorption because only
photons with energy greater than the bandgap can be absorbed by the material.
Since the effective response of a silicon solar cell comprises the range of 600 to
900 nm, a non-negligible portion of the solar spectrum is not utilized for photon
absorption. The aforementioned shortcoming could be addressed by using
photoluminescent quantum dots that exhibit a Stokes shift as a method to
improve the spectral response of short wavelength photons in silicon solar cells
by absorbing photons in the range of 300-450 nm and re-emitting in the range
of 500-600 nm where the device exhibits a better response. Quantum dots (QD)
are semiconductor structures that confine charge carriers to a nanoscale region
that are described by quantum mechanics, exhibit different behavior compared
to bulk materials because the surface/volume ratio affects their physical and
chemical properties, their electronic properties are strongly related to its size
and by varying their size it is possible to obtain emission in different
wavelengths. Thus, judiciously employed, the ability of quantum dots (QDs) to
absorb high energy photons and emit photons with lower energy could be
exploited to increase the efficiency of solar cells. We report the synthesis and
characterization of silicon (Si) and zinc oxide (ZnO) quantum dots (QDs), that
exhibit down-shifting photoluminescent characteristics, and their deployment
on photovoltaic devices. The thickness of photoluminescent coatings for silicon
solar cells was theoretically optimized to reduce reflectivity and experimentally
verified for a variety of configurations, including single-layer and double-layer
coatings. It is possible to make variations in concentration and thickness to
optimize this result. The combined effect of the coatings led to an increase in
energy conversion efficiency (PCE) of around 14.86% to 15.5%. These increases
represent improvements of around 6.4% of the power conversion efficiency
(PCE) of the photovoltaic devices used.