Yang Bai

Full list of publications: https://scholar.google.fi/citations?user=70G9UvsAAAAJ&hl=en)

Research output and dissemination

• 52 peer-reviewed publications, including 23 as first author and 36 as corresponding author
• Five granted patents, three patent applications and two invention disclosures
• Two university blogs
• Eight times as panel member or proposal reviewer
• Referee for over 45 academic journals including prestigious ones such as Advanced Materials, Journal of the American Chemical Society, and PNAS
• Ten times as scientific conference/symposium/workshop organiser
• Four times as editors for books or journal special issues
• 17 times as invited or keynote speakers at scientific conferences or events
• Seven talks or exhibitions for public engagement and outreach
• Several press releases about own scientific results
• Contribution to institutional road map

Scientific achievement 1: Multifunctional energy harvesting, Energy-as-Data concept, and startup

Since 2016, I have been pioneering multi-source (multimodal) energy harvesting, where the idea was to use a single material to harvest multiple energy sources, including light (via the photovoltaic effect), heat (via the pyroelectric effect), and motion (via the piezoelectric effect). By engineering the band gap of piezoelectric ceramics, I have successfully demonstrated the feasibility of using a single material to harvest multiple energy sources [1,2]. This was considered a groundbreaking result and hence I was invited by Advanced Materials to write a review article on the topic of multi-source energy harvesting [3]. This article is highly cited in the field of enregy hravesting.

My multi-source energy harvesting research results were also deemed valuable for commercial exploitation. In 2020, I was granted a Research-to-Business project funding by Business Finland. During 2020-2025, the results have gained intellectual property rights under granted patents in the UK, USA, and member states of the European Patent Organisation [4].

I have also made efforts on exploiting the commercial feasibility of multi-source energy harvesting and eventually, I have proposed an emerging concept, Energy as Data, which is a new way of using the intermittent ambient energy in a sustainable manner. This concept is published as a featured article [5] on Applied Physics Letters. This new concept has also guided the design of the prototype for a cough sensing system, where the battery life could be significantly extended by up to 21 times. The prototype has become the foundation of a startup, Emedpatch Oy, in 2022, in which I was one of the founders.

[1] Y. Bai et al. Adv Mater 29 1700767 2017; [2] Y. Bai et al. Energy Technol 8 2000461 2020; [3] Y. Bai et al. Adv Mater 30 1707271 2018; [4] Y. Bai Granted patents GB2593105B/US11613503B2/EP4069658B1; [5] Y. Bai Appl Phys Lett 124 110502 2024

Scientific achievement 2: Fundamental photoferroelectrics research and ERC grant

For over 100 years, people have known the fact that electric domains in ferroelectrics can be switched by external electric field, by applied stress, and by changed temperature. However, until 2018-2019, we were not convinced by the fact that electric domains in ferroelectrics can also be switched by incident light. In 2019, my collaborators and I published two of our papers (on Advanced Materials and Advanced Optical Materials) discussing the photo-induced domain switching in ferroelectrics both at the macroscale and nanoscale [1,2]. Beside other papers published by peers in the same period, we independently proved the physical phenomenon of incident photons being able to switch ferroelectric domains for the first time in history.

Following our discovery of the photo-induced domain switching, in 2020-2023, I continued my fundamental study towards the exploration of making functional materials out of the photoferroelectric effect. One of the pioneer investigations is the use of the cumulative optoelectric ferroelectricity for current modulation [3] (highlighted as an editor’s pick on ACS Applied Electronic Materials), which has induced a new type of photodetector that does neither rely on conventional semiconductors to measure the light intensity nor need optical filters to distinguish different wavelengths [4] (highlighted as a front cover page on Solar RRL).

Due to my achievements in photoferroelectrics research and my ambitious research idea regarding the bulk photovoltaic effect, in 2022, I was granted an ERC Starting Grant and then I started to lead the project. To date, we have studied the seemingly only viable route towards an optimised bulk photovoltaic effect in ferroelectrics, that is the construction of a stacked domain structure. Taking advantage of the earlier hypothesis as well as the recently identified methodology reported by peers for constructing such a domain structure, my team has successfully validated the above-mentioned optimisation route via experiment. The result [5] is highlighted as a back cover page on Advanced Electronic Materials.

We are currently on the track of approaching our final goal in my ERC project.

[1] Y. Bai et al. Adv Mater 30 1803821 2018; [2] G. Vats and Y. Bai et al. Adv Opt Mater 7 1800858 2019; [3] G. Vats and Y. Bai et al. ACS Appl Electron Mater 2 2829-2836 2020; [4] V. A. Balanov and Y. Bai et al. Solar RRL 7 2200995 2023; [5] V. Balanov and Y. Bai et al. Adv Electron Mater 11 2400471 2025

Scientific achievement 3: Sustainable development and recycling of piezoelectric ceramics

Most high-performance functional ceramics contain hazardous element, Pb. EU’s Restriction of Hazardous Substances (RoHS) Directive has been introduced for over two decades. The RoHS required to eliminate, for example, the use of Pb in electronic components. However, the use of Pb in high-performance piezoelectric ceramics has exempted several times, simply because researchers had difficulties of finding environmentally friendly alternatives comparable to the Pb-containing counterparts in terms of the material’s functional performance.

My research has contributed to pushing the adoption of RoHS in high-performance piezoelectrics. In 2013-2015, I helped to answer the scientific question about to what extent the (Ba,Ca)(Zr,Ti)O₃ (BCZT) ceramics, one of the limited Pb-free options, can compete with the Pb-containing piezoelectric ceramics [1].

Furthermore, high-performance functional ceramics must be sintered at over 1000 °C. The high energy consumption during sintering leaves a heavy eco-footprint behind the ceramics industry. In 2022, my team started to explore the feasibility of recycling piezoelectric ceramics. The recycling methodology is based on the upside-down compositing technique. In the recycling procedure, we managed to combine waste piezoelectric ceramics that have an oxide perovskite structure with binders having a halide perovskite structure [2,3]. As halide perovskites are also widely used in solar cells, we were even able to recycle waste solar cells at the same time [4].

The methodology proves to be true recycling instead of downcycling, because our recycled materials have been given a second life as candidate materials for piezoelectric sensors. Our recycled materials outperformed the pristine, source ceramics in terms of the piezoelectric voltage coefficient, an indicator of sensitivity. We are currently working on scaling up the recycling procedure using machine learning-assisted prediction of the properties of any recycled piezoelectric ceramics, for example, with unknown or mixed recycled sources [5]. A potential success will solve the problems of hazardous Pb and high energy consumption simultaneously by preventing the already fabricated components from ending up as wastes in the environment.

[1] Y. Bai et al. J Eur Ceram Soc 35 3445-3456 2015; [2] S. S. Anandakrishnan and Y. Bai et al. RSC Sustain 2 961-974 2024; [3] M. Tabeshfar and Y. Bai et al. Journal of the American Ceramic Society 108 e20714 2025; [4] M. Tabeshfar and Y. Bai et al. Small Methods 8 2300830 2024; [5] S. S. Anandakrishnan and Y. Bai et al. Materials & Design 254 114044 2025