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

• DOI: 10.1038/srep28313
• Publication Date: 2016-06-17T09:42:19Z
• Authors: Hyunji An; Jun Young Han; Bongjae Kim; Jaesun Song; Sang Yun Jeong; Cesare Franchini; Chung Wung Bark; Sanghan Lee
• Keywords: Photocurrent; Visible spectrum

Abstract Tuning the bandgap in ferroelectric complex oxides is a possible route for improving photovoltaic activity of materials. Here, we report realization this effect epitaxial thin films oxide Bi 3.25 La 0.75 Ti 3 O 12 (BLT) suitably doped by Fe and Co. Our study shows that Co (BLCT) doping combined Fe, (BLFCT) lead to reduction more than 1 eV compared undoped BLT, accompanied surprisingly efficient visible light absorption. Both BLCT BLFCT can absorb with wavelength up 500 nm while still exhibiting ferroelectricity, whereas BLT only absorbs UV less 350 nm. Correlated its reduction, film photocurrent density enhanced 25 times films. Density functional theory calculations indicate contraction caused formation new energy states below conduction bands due intermixed transition metal dopants (Fe, Co) BLT. This mechanism tuning simple be applied other wide-bandgap oxides, thereby enabling their use solar conversion or optoelectronic applications.