Study on the fundamentals and applications of photoferroelectric materials: Insights into photoconductivity and the bulk photovoltaic effect
Thesis event information
Date and time of the thesis defence
Place of the thesis defence
LO124 Areena, Linnnamaa campus
Topic of the dissertation
Study on the fundamentals and applications of photoferroelectric materials: Insights into photoconductivity and the bulk photovoltaic effect
Doctoral candidate
Master of Science Vasilii Balanov
Faculty and unit
University of Oulu Graduate School, Faculty of Information Technology and Electrical Engineering, Microelectronics
Subject of study
Electrical engineering
Opponent
Professor Joe Briscoe, Queen Mary University of London
Custos
Associate Professor Yang Bai, University of Oulu
Ferroelectric materials for light detection and energy conversion
Ferroelectric materials are widely used because they can change their electrical properties when exposed to external stimuli such as mechanical stress, temperature, or electric fields. This thesis investigates what happens when these materials interact with light and explores how their light-induced electrical response can be used in practical applications.
The study focuses on how the composition and internal structure of ferroelectric materials affect their ability to absorb light, generate electrical charges, and transport these charges through the material. In particular, the research examines how different crystal structures, imperfections in the material, and the arrangement of microscopic regions with different electrical orientations influence the resulting photoresponse.
Several types of ferroelectric ceramics and single crystals were investigated experimentally. The results show that the crystal structure plays an important role in determining which wavelengths of light a material can absorb, while its internal domain structure strongly affects the electrical response generated by illumination. The study also demonstrates that the photoresponse can be controlled by combining an external electric field with different wavelengths of incident light.
This behaviour was used to demonstrate a new type of wavelength-selective photodetector that does not require conventional filters to distinguish between different colours of light. Such an approach could potentially enable compact and integrated colour-sensing devices.
Although the efficiency of these materials for converting light into electrical energy is currently limited, the results provide guidelines for improving their performance. Materials with stronger light absorption, suitable electrical properties, and carefully controlled internal structures could in the future be used in multifunctional sensors and energy-conversion technologies.
The study focuses on how the composition and internal structure of ferroelectric materials affect their ability to absorb light, generate electrical charges, and transport these charges through the material. In particular, the research examines how different crystal structures, imperfections in the material, and the arrangement of microscopic regions with different electrical orientations influence the resulting photoresponse.
Several types of ferroelectric ceramics and single crystals were investigated experimentally. The results show that the crystal structure plays an important role in determining which wavelengths of light a material can absorb, while its internal domain structure strongly affects the electrical response generated by illumination. The study also demonstrates that the photoresponse can be controlled by combining an external electric field with different wavelengths of incident light.
This behaviour was used to demonstrate a new type of wavelength-selective photodetector that does not require conventional filters to distinguish between different colours of light. Such an approach could potentially enable compact and integrated colour-sensing devices.
Although the efficiency of these materials for converting light into electrical energy is currently limited, the results provide guidelines for improving their performance. Materials with stronger light absorption, suitable electrical properties, and carefully controlled internal structures could in the future be used in multifunctional sensors and energy-conversion technologies.
Created 11.8.2026 | Updated 12.8.2026