Bern Mae Yu Jeco-Espaldon (Okada Lab)

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• I completed my doctoral program at the Department of Advanced Interdisciplinary Studies (AIS) at the Graduate School of Engineering in March 2020. My doctoral research focused on improving solar cell efficiency. Separately, I also did research on using ultraviolet light-emitting diodes (UV-LED) to paralyze bacteria in water. I am a postdoctoral researcher (JSPS research fellow) at the Graduate School of Engineering, where I continue to study solar cells and UV-LED water treatment.

  Desire to address Philippines’ power and water problems

  I decided to attend graduate school after graduating from the University of Santo Tomas in the Philippines in 2011 because I aspire to be a professor in my home country. I have liked Japanese anime since I was child, so I had long wanted to visit Japan. Fortunately, I got accepted into the Ajinomoto Scholarship Program, which opened the door to studying in a master’s program at the University of Tokyo. I took an examination and was admitted to the master’s program. I was interested in solar cells before coming to Japan because I thought they could greatly help my home country, where a considerable number of people have no access to electricity. I studied solar cells in the laboratory of Professor Yoshitaka OKADA and then advanced to the doctoral program at AIS to continue my research. Our research at the Okada Lab examined the spatial distribution of electricity generation in a solar cell by picturing each light-absorbing layer of the cell on a separate plane. This was a novel approach because most researchers look at the cell as a whole.

Professor OKADA suggested that I collaborate with Associate Professor Kumiko OGUMA of the Department of Urban Engineering on a water treatment research project in Asian nations. This project was part of my coursework in AIS, which encourages students to work with professors from different fields (through leadership-talent growth programs). That’s how the solar-powered UV-LED water treatment system project came about. The Philippines is surrounded by water but, ironically, lacks sources of drinking water. Finding a solution to this problem was another motivation for pursuing my work. In addition to the one-year coursework, Associate Professor OGUMA kindly let me work at her lab and funded some field studies in the Philippines.

Fell in love with science at the University of Tokyo

I always considered myself technically challenged. Moving from the Philippines to Japan, which has much more advanced technology, was a massive challenge for me. But now I am more confident about collaborating with other researchers, whether they’re at the peak of their career or just starting. I also feel humbled that some people now ask me to share my knowledge with them.

In fact, I fell in love with science while doing research in the master’s program and at AIS. It is still quite rare for women to pursue a career in science, but I want to tell everyone that science and technology is not only for men. Women can enjoy this field and thrive in it.

Most courses at AIS are conducted in English, so international students do not need to worry about a language barrier. My Japanese still is not at college level, but I have no trouble communicating with my colleagues. The environment at the Okada Lab is very international, so I got the chance to talk with different researchers from other institutions. I was able to discuss my research with people from Japan and abroad. I am grateful to have studied under Professor OKADA because I got opportunities to present my work at international conferences.

I am researching material science. I focus on different materials to improve solar cell performance and enable the recycling of light within solar cells. In technical terms, this is called luminescent coupling for multijunction solar cells. Conventional solar cells use a single material, silicon, but they suffer power output loss. To overcome this problem, we stacked layers of different materials so that the solar cell can trap sunlight better.

Under the UTEC Young Researchers’ Challenge Support Program for promising researchers at the University of Tokyo’s Komaba Research Campus, I traveled to the University of San Agustin in the Philippines in 2020 to conduct fieldwork on the feasibility of a solar-powered UV-LED water treatment system on a remote island in the Philippines. We did fieldwork in very hot and humid conditions and needed to take extensive precautions to prevent COVID-19 outbreaks, but we accumulated useful data for publication. UV-LEDs do not kill harmful bacteria in water; they inactivate them so people can drink without getting sick. My research under Associate Professor OGUMA has demonstrated that such a system is viable where both safe drinking water and electricity are in short supply. Meeting with Associate Professor OGUMA was a breakthrough for me because I got a close-up view of a major problem in my home country.

AIS a great option for international students

I want to continue my postdoctoral work about solar cell materials beyond my current stint that ends in March 2022. I am a working mother who enrolled my daughter in a nursery school as soon as possible after childbirth to pursue my career in solar cell material science research. Producing original research usually requires a lot of time so I have to work as fast as possible.

If my schedule permits, I am thinking of doing part-time teaching to some chemistry students. Teaching is a passion of mine, so I would love to become a full-fledged professor in the Philippines one day.

My advice to international students who are considering studying at AIS is do it! The environment here is really inclusive, and it also accommodates those with industry links and experience. It doesn’t really matter if you’re from Japan or abroad. For many scientists, sharing their expertise with the public can be difficult. AIS and the Okada Lab taught me how to convey and explain my research through coursework and presentations. If you want to become a better science communicator, I think AIS is an excellent place to start.