Strongly enhanced and tunable photovoltaic effect in ferroelectric-paraelectric superlattices

Yeseul Yun; Lutz Mühlenbein; David S Knoche; Andriy Lotnyk; Akash Bhatnagar

doi:10.1126/sciadv.abe4206

Strongly enhanced and tunable photovoltaic effect in ferroelectric-paraelectric superlattices

Sci Adv. 2021 Jun 2;7(23):eabe4206. doi: 10.1126/sciadv.abe4206. Print 2021 Jun.

Authors

Yeseul Yun^{1

2}, Lutz Mühlenbein^{1

2}, David S Knoche^{1

2}, Andriy Lotnyk^{3

4}, Akash Bhatnagar^{5

2}

Affiliations

¹ Zentrum für Innovationskompetenz SiLi-nano, Martin-Luther-Universität Halle-Wittenberg, 06120 Halle, Germany.
² Institute of Physics, Martin-Luther-Universität Halle-Wittenberg, 06120 Halle, Germany.
³ Leibniz Institute of Surface Engineering (IOM), 04318 Leipzig, Germany.
⁴ Laboratory of Infrared Materials and Devices, The Research Institute of Advanced Technologies, Ningbo University, 315211 Ningbo, China.
⁵ Zentrum für Innovationskompetenz SiLi-nano, Martin-Luther-Universität Halle-Wittenberg, 06120 Halle, Germany. akash.bhatnagar@physik.uni-halle.de.

Abstract

Ever since the first observation of a photovoltaic effect in ferroelectric BaTiO₃, studies have been devoted to analyze this effect, but only a few attempted to engineer an enhancement. In conjunction, the steep progress in thin-film fabrication has opened up a plethora of previously unexplored avenues to tune and enhance material properties via growth in the form of superlattices. In this work, we present a strategy wherein sandwiching a ferroelectric BaTiO₃ in between paraelectric SrTiO₃ and CaTiO₃ in a superlattice form results in a strong and tunable enhancement in photocurrent. Comparison with BaTiO₃ of similar thickness shows the photocurrent in the superlattice is 10³ times higher, despite a nearly two-thirds reduction in the volume of BaTiO₃ The enhancement can be tuned by the periodicity of the superlattice, and persists under 1.5 AM irradiation. Systematic investigations highlight the critical role of large dielectric permittivity and lowered bandgap.

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