College of Engineering

Deng A.D Kuol

College of Arts & Sciences Physics

Faculty Mentor: Dr. Jonathan E. Spanier Materials Science & Engineering

Dr. Radhe Agarwal, Liyan Wu, Andrew Benett-Jackson Co-Mentors

The bulk photovoltaic effect (BPVE) is a light to energy conversion mechanism, which occurs in crystal structures which lack a center of symmetry1. This allows the entire material to be both a light absorber and photon-induced electron-hole pair separator2, unlike conventional photovoltaic (PV) devices which operate by a pn junction or interface. Furthermore, the BPVE, which can be found in ferroelectric oxides is reported to produce open-circuit voltages much larger than the band gap of the given material3, but prohibitively low photocurrents1. This class of materials has exciting prospects for the next generation of PV devices due to their lack of need for a pn junction, use of earth abundant-element and nontoxic materials, and high photo voltages. As such this work aims to increase the light absorption of wide bandgap ferroelectric oxides via bandgap engineering4, where a dopant is introduced into the material structure. Thus, altering the electronic and optical properties. Pulsed laser deposition was used to grow a series of thin films from a doped perovskite oxide target. The films were characterized using X-ray diffraction techniques, UV-visible light transmission, and ferroelectric hysteresis.

References:

1. Sturman, B. & Fridkin, V. The Photovoltaic and Photorefractive Effects in Noncentrosymmetric Materials (Gordon and Breach, 1992).

2. Yang, S. Y. Above-Bandg ap voltages from ferroelectric photovoltaic devices Nature Nano. 5, 143-147 (2010)

3.Johnathan, E. S. & Fridkin, V. Power conversion efficiency exceeding the Shockley–Queisser limit in a ferroelectric insulator, Nature Photo. 10, pages 611–616 (2016)

4. Riad, N. Bandgap tuning of multiferroic oxide solar cells Nature Photo. 9, 61-67 (2015)