Large enhancement of the photovoltaic effect in ferroelectric complex oxides through bandgap reduction

Autor(en)

Hyunji An, Jun Young Han, Bongjae Kim, Jaesun Song, Sang Yun Jeong, Cesare Franchini, Chung Wung Bark, Sanghan Lee

Abstrakt

Tuning the bandgap in ferroelectric complex oxides is a possible route for improving the photovoltaic activity of materials. Here, we report the realization of this effect in epitaxial thin films of the ferroelectric complex oxide Bi3.25La0.75Ti3O12 (BLT) suitably doped by Fe and Co. Our study shows that Co (BLCT) doping and combined Fe, Co (BLFCT) doping lead to a reduction of the bandgap by more than 1 eV compared to undoped BLT, accompanied by a surprisingly more efficient visible light absorption. Both BLCT and BLFCT films can absorb visible light with a wavelength of up to 500 nm while still exhibiting ferroelectricity, whereas undoped BLT only absorbs UV light with a wavelength of less than 350 nm. Correlated with its bandgap reduction, the BLFCT film shows a photocurrent density enhanced by 25 times compared to that of BLT films. Density functional theory calculations indicate that the bandgap contraction is caused by the formation of new energy states below the conduction bands due to intermixed transition metal dopants (Fe, Co) in BLT. This mechanism of tuning the bandgap by simple doping can be applied to other wide-bandgap complex oxides, thereby enabling their use in solar energy conversion or optoelectronic applications.

Organisation(en)

Computergestützte Materialphysik

Externe Organisation(en)

Gwangju Institute of Science and Technology (GIST), Gachon University

Journal

Scientific Reports

Band

6

Anzahl der Seiten

7

ISSN

2045-2322

DOI

https://doi.org/10.1038/srep28313

Publikationsdatum

06-2016

Peer-reviewed

Ja

ÖFOS 2012

103009 Festkörperphysik, 103015 Kondensierte Materie, 103025 Quantenmechanik, 103036 Theoretische Physik

Schlagwörter

Sustainable Development Goals

SDG 7 – Bezahlbare und saubere Energie

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/fd863912-c3e5-4729-8156-8d9a2d39e288