Abstracts Book - IMRC 2018

• SC4-P088
THEORETICAL AND EXPERIMENTAL STUDY OF THE OPTICAL AND
ELECTRONIC PROPERTIES OF BiFeO3 AND (Bi0.9La0.1) FeO3 FOR
PHOTOVOLTAIC APPLICATIONS
Espiridión Martínez 1,2 , H´ Linh H´ Mok 1,2 , María Guadalupe Moreno Armenta 3 , Jesús María
Siqueiros Beltrones 2
1
Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE), Posgrado en
Física de Materiales, Mexico. 2 Centro de Nanociencias y Nanotecnología CNyN-UNAM,
Departamento de Materiales Avanzados, Mexico. 3 Centro de Nanociencias y Nanotecnología
CNyN-UNAM, Departamento de Nanoestructuras, Mexico.
In recent research, the anomalous photovoltaic effect (APVE) in ferroelectric
materials has been considered as a favorable option for the harvest of solar
energy. The effect is manifested by the appearance of a stationary current in
ferroelectric samples in short circuit and under illumination with light of
wavelengths corresponding to its absorption spectrum. However, for
application purposes, this interval is the main limitation since the energy gap of
ferroelectric materials is typically around and above 3 eV. In particular, the
BiFeO3 multiferroic material (BFO) has an experimental gap of ~ 2.7 eV, which
makes it a promising material for design processes and bandwidth adjustment
and a candidate for photovoltaic devices. In order to reduce the width of the
forbidden band of BFO, the effect of doping with La at 10% is studied
theoretically and experimentally. The theoretical behavior was studied with the
use of the density functional theory (DFT) with generalized gradient
approximation (GGA) plus the U (Hubbard) correction. The results show that the
electronic structure of BiFeO3 was locally affected by a distortion of the oxygeniron
octahedron of the unit cell. These changes were reflected in the behavior
of the systems spontaneous polarization. In our calculations, the change in
Fermi energy was favorable reducing the gap to 2.4 eV Experimentally thin films
have been obtained with the magnetron ion sputtering technique and have
been analyzed with ellipsometry and UV-VIS spectroscopic technique. The
experimental results of the films of BFO and La doped BFO coincide to a large
extent with those obtained in the calculations.
Acknowledgment:
We appreciate the support of CoNaCyT, project_280309 and A1-S-9965, as well
as PAPIIT-DGAPA-UNAM No. IN105317.