Improving the materials used in photovoltaic devices could lead to much higher efficiencies in energy conversion, thus enabling cleaner and more cost effective energy solutions
Subhashri Chatterjee, our next pathbreaker, Research Associate at NTT Basic Research Laboratories ( BRL, Japan), focuses on discovering new quantum phenomena in a special class of materials, with applications in energy conversion and ultrafast data communication at terahertz (THz) frequencies.
Subhashri talks to Shyam Krishnamurthy from The Interview Portal about doing his BTech in Electronics, but his PhD in Chemical Engineering which not only required chemistry-intensive work — synthesizing nanomaterials, and handling sensitive processes, but also ensuring they functioned in photonics applications.
For students, If you truly want to be a scientist, an engineer, or a researcher, you have to find your own route, even if it’s unconventional.
Subhashri, can you share your background with our young readers?
My name is Subhashri Chatterjee. I grew up in Memari, a small town in the Burdwan district of West Bengal. While schools and colleges were present, access to quality education and information was limited. From childhood, I was an average student. I never enjoyed conventional schooling and didn’t pay much attention to marks. Instead, I was more interested in truly understanding the subjects being taught.
Early on, I developed a strong interest in mathematics, which later extended to physical sciences. This curiosity eventually guided me toward studying electronics engineering. Outside of academics, I started playing cricket around the age of five or six and spent a lot of time watching cricket matches and cartoons on TV. These were typical extracurricular activities for children during that time.
My interest in engineering began early. My brothers were preparing for engineering entrance exams, and from around class 5 or 6, I set my goal to become an engineer like them. They were academically stronger than me, but I always believed in giving my best effort. As I grew older, I came to understand that gaining admission wasn’t just about academic performance— financial resources played a big role too.
My father is a businessman who runs a shop that sells automobile and tractor parts. My mother is a homemaker. We lived in a joint family, and with limited financial means, it was difficult for my father to fulfil all our wants. We belonged to a lower middle-class background, and that reality shaped much of my early life and ambitions.
What did you do for graduation/post graduation?
After completing high school, I attempted the AIEEE twice but couldn’t secure a strong rank. Eventually, I enrolled in a private engineering college in West Bengal through WBJEE, under the West Bengal University of Technology (WBUT), and completed my BTech in Electronics Engineering in 2015. My family took an education loan from SBI to support my studies. From the beginning of my undergraduate program, I set a clear goal—to pursue a master’s in Electronics from an IIT through GATE, as studying abroad seemed financially out of reach at the time.
During my BTech, I shared my aspiration of becoming a scientist—not just an engineer—with one of my professors. He encouraged me to read journal articles and gain research experience, explaining that it would strengthen my chances for higher studies. Under his mentorship, I got involved in several research projects where I learned how to conduct experiments and write academic papers. My interests centered around photodetectors, infrared sensing, quantum physics, and solid-state devices. By the time I graduated, I had co-authored multiple papers and developed a solid foundation in academic research.
Although I couldn’t clear GATE in 2015, I accepted a job as a network engineer at Huawei Telecommunications India Pvt. Ltd. Despite the modest salary, I used the opportunity to build practical knowledge in the telecommunications field while continuing to explore academic paths abroad.
In mid-2016, the same professor informed me about opportunities in Japan, where it was possible to pursue a master’s and PhD with scholarships and full tuition waivers. In October 2017, I was awarded the JASSO and ABP scholarships at Shizuoka University for a master’s program in Electronics and Materials Science, with complete tuition waiver. My research focused on metamaterials and laser lithography, within nanophotonics and optoelectronics.
I participated in multiple research projects and was fortunate to receive two awards—Best Young Researcher and Best Presenter—at academic conferences in Yokohama and Hamamatsu in 2018.
October 2019, After completing my master’s, I was admitted to the PhD program at Hokkaido University, jointly with the National Institute for Materials Science (NIMS), one of the leading materials research institutes globally. I worked there as a junior researcher for 4.5 years. Throughout both my master’s and PhD, my tuition fees were fully waived, and I was independently responsible for all living expenses through scholarships and research assistantships. During my PhD, I was also able to fully repay the education loan taken for my undergraduate studies.
After completing my doctorate, I received offers for research positions from AIST (Japan), and NTT Basic Research Laboratories (Japan). Additionally, I was also nearly selected for postdoctoral positions at top research institutes like ICFO and IMEC, making it to the final stages of the process. But I chose NTT BRL, as it offered the unique opportunity to conduct fundamental research within an industry setting. I am currently working there as a Research Associate, focusing on quantum terahertz sensing and quantum material physics.
What were some of the key influences that led you to such an offbeat, unconventional, and unique career in Materials Research?
My journey toward a career in science and research was shaped by a combination of family influence, mentorship, persistence through failure, and a few defining turning points. The earliest inspiration came from my two elder brothers—Indranath Banerjee, who works at Ericsson, and Soumya Banerjee, who is with McKinsey & Company. Watching them pursue engineering sparked my own interest in the field from a very young age. I looked up to them and set my sights on following a similar path.
During my undergraduate studies, two people had a profound impact on my academic and personal development. Dr. Samsaptak Ghosh, a childhood friend and mentor, encouraged me to think critically and aim higher. But it was Prof. Aritra Acharyaa, my professor during BTech, who truly changed the trajectory of my life. He introduced me to the world of research, pushed me to read academic journals, and gave me opportunities to work on real projects. That early exposure not only shaped my understanding of science but also helped me develop the mindset needed for a long-term career in research.
Later, in 2016, Dr. Amit Banerjee played a pivotal role by guiding me through the complex process of applying for graduate programs in Japan. His encouragement came at a time when studying abroad seemed financially and logistically impossible.
My research path truly took shape under the mentorship of two remarkable professors: Prof. Vygantas Mizeikis during my master’s studies, and Prof. Naoto Shirahata during my PhD. Their belief in my potential and their rigorous academic guidance helped refine my skills and shape my research career. They challenged me to ask deeper questions, think independently, and persevere through setbacks. I also owe special thanks to Prof. Batu Ghosh, whose insightful discussions and continuous support throughout my PhD were instrumental in helping me navigate the scientific challenges and broaden my understanding of the work.
There were many failures along the way, but a few key turning points defined my journey. One of the most significant was deciding to pursue higher education and research in Japan. The country’s robust education system, deeply rooted culture of innovation, and legacy of Nobel-winning scientists showed me what a strong commitment to research can achieve. Another turning point was earning my doctoral degree—a goal that once felt far beyond reach, and is now one of my proudest achievements.
But if I had to point to one night that truly changed everything, it would be December 27, 2021. After two years of failed experiments and more than 50+ trials, I finally succeeded. That moment— alone in the lab, staring at the result I had fought so hard for —was a breakthrough not just scientifically, but personally. It gave me the confidence that I belonged in research, and it directly led to my doctoral publications and the completion of my PhD. I’ll never forget that night, because it reaffirmed my belief that persistence, even through failure, always pays off.
How did you plan the steps to get into the career you wanted? Or how did you make a transition to a new career? Tell us about your career path
After completing my BTech in Electronics Engineering in 2015, I began my career as a Network Engineer at Huawei Telecommunications India Pvt. Ltd. Although the role wasn’t directly aligned with my long-term goals, I used that time to build industry knowledge and prepare for graduate studies. I applied to graduate programs in Japan, attracted by the strong research ecosystem and available scholarships.
In 2017, I joined Shizuoka University for a Master’s in Electronics and Materials Science, supported by the JASSO and ABP scholarships, with full tuition waived. My research focused on metamaterials and nanophotonics, and I gained hands-on experience through multiple projects and conference presentations.
Imagine if you could wear a cloak and completely disappear—just like Harry Potter’s invisibility cloak! While that might seem like pure magic, scientists today are getting closer to making that possible using metamaterials—special materials that can bend light around an object, making it invisible to the human eye or to cameras. In my research, I worked on creating these kinds of materials in the lab. We don’t use magic wands — we use laser lithography, which is like using a super precise laser to “draw” tiny 3D structures, much smaller than a grain of dust. These structures, called metasurfaces, can do amazing things with light—like absorbing all the infrared light (like heat) or making objects appear invisible at certain wavelengths. We even coat them with gold to fine-tune their powers!
What’s really cool is that these technologies aren’t just for fun—they have real uses in the world: in defense, they could help make invisible uniforms or heat-proof shields; in space, they could improve how satellites send and receive signals; and in medicine, they could help build better imaging tools that see more clearly inside the body. So while we’re not quite at Hogwarts yet, the science behind Harry’s cloak is happening right now in research labs across Japan—and I’m lucky to be part of it!
These experimental experiences led to a PhD opportunity in Chemical Engineering at Hokkaido University and NIMS, where I worked as a Junior Researcher for 4.5 years in Quantum Devices and Photonics.
Though my background is in Electronics and Communication Engineering, I’ve always been more curious about the science behind the technology—the “why” and “how” things work at the most fundamental level. That curiosity naturally pulled me beyond pure engineering and into a more interdisciplinary path, leading to a PhD in Chemical Engineering. My research focused on Indium Antimonide (InSb) colloidal quantum dots (CQDs) for short-wave infrared (SWIR) sensing—the kind used in night vision, autonomous vehicles, and advanced imaging. What makes this exciting is that solution-processed CQDs can reduce the cost of infrared cameras by up to 100 times compared to existing technologies, making them accessible for everyday use. Plus, InSb is non-toxic, which is crucial for safety and sustainability. I wasn’t trained as a chemist, but I believed that with curiosity and tenacity, one can learn anything. So, I learned the synthesis from fellow chemists, made the materials myself, and then used my electronics background to build the device side. This project even attracted industry interest—Panasonic was initially involved, aiming to use this material for a next-gen infrared camera. Unfortunately, after nearly two years of failed attempts, the collaboration ended. But that struggle taught me everything. Today, I see startups turning the same technology into real products. It’s inspiring to know that the field is moving forward, and I’m proud to have contributed to it, even in a small way.
Throughout this journey, my focus was always on building deep research skills and contributing meaningfully to science. Today, I work at NTT Basic Research Labs, where I conduct cutting edge research in quantum terahertz sensing and quantum material physics—an outcome of strategic decisions, strong mentorship, and a steady commitment to research excellence.
How did you get your first break?
I got my first break after completing my PhD, when I received multiple offers from top research institutes. I chose NTT BRL because it uniquely combines industrial innovation with fundamental research, aligning perfectly with my long-term goal of contributing to basic science while staying connected to real-world applications.
What were some of the challenges you faced? How did you address them?
Challenge 1: The toughest challenge was dealing with repeated failures—failed experiments, paper rejections, and prolonged uncertainty. In research, these setbacks are common, but facing them continuously tests both patience and confidence. One defining example was during my PhD, when I spent nearly two years trying to fabricate and demonstrate a working photodetector using InSb colloidal quantum dots. Over 50+ failed attempts led several researchers to abandon the project, believing it was a dead end. But I continued, driven by curiosity and belief in science.
Challenge 2: As someone with a background in electronics engineering, it was especially difficult to dive into chemistry-intensive work — synthesizing nanomaterials, handling sensitive processes, and ensuring they functioned in photonics applications. Bridging that knowledge gap while producing working optoelectronic devices required both steep learning and persistence.
Challenge 3: Staying consistent and holding onto long-term goals through these obstacles was also challenging. Research doesn’t offer instant gratification. It demands patience, self-discipline, and resilience over months and years. Doubts about whether I would ever achieve my goals were common, but I learned to accept failures as part of the process.
The turning point came on the night of December 27, 2021, when my experiment finally succeeded. That result proved for the first time that InSb colloidal quantum dots could be used as photodiodes for infrared sensing—a breakthrough that led to a publication and recognition for being the first to demonstrate this. That moment reminded me that true research is not about short term success, but the ability to believe, endure, and persist until science speaks.
Where do you work now? What problems do you solve?
I currently work at NTT Basic Research Laboratories (BRL) as a Research Associate, where I focus on discovering new quantum phenomena in Weyl semimetals, with applications in energy conversion and ultrafast data communication at terahertz (THz) frequencies. Traditional energy conversion methods have limitations, but theoretical physics suggests that much higher efficiencies are possible if we identify the right materials and engineer their band structures. Quantum physical phenomena are key to unlocking this potential. My work specifically explores Weyl materials, which are promising candidates for quantum sensing and quantum computing.
What skills are needed for your role?
The skills required for this role span across nano device fabrication, electronic device engineering, optics, photo-physics, and materials science. I acquired these skills throughout my academic journey, from my Bachelor’s in Electronics Engineering to my PhD, where I developed a deep understanding of both theoretical and practical aspects of these fields.
What’s a typical day like?
A typical day at work begins with planning experiments from 9 to 9:30 AM, followed by hands on experimental work from 10 AM to 12 PM. After a lunch break, I continue with experiments and data collection, and in the evenings, I summarize the results and prepare for bi-weekly presentations to my manager. Every few months, I present my findings at academic conferences and write full papers for publication in scientific journals. When I’m focused on manuscript writing, my day revolves around compiling data, creating figures, and refining the narrative of my research, often working until late in the evening.
What is it you love about your work?
What I truly love about my job is the continuous learning and the thrill of discovery. Science is full of surprises—what we hypothesize doesn’t always match what we observe, and that’s what makes it so exciting. I enjoy working with cutting-edge instruments to solve problems at the nanoscale and the opportunity to collaborate with researchers from around the world. Most of all, I am passionate about contributing to the scientific community by publishing new research that advances our understanding and benefits society.
How does your work benefit society?
My current research on Weyl semimetals for energy conversion and fast photodetection has the potential to significantly benefit society by addressing critical challenges in energy efficiency and communication technologies. Energy conversion is essential for sustainable power generation, and my work on improving the materials used in photovoltaic devices could lead to much higher efficiencies, enabling cleaner and more cost effective energy solutions. Additionally, the fast photodetectors I am working on can revolutionize high-speed data communication, especially in the terahertz frequency range, facilitating faster, more reliable internet and communication systems. My research also extends to applications in infrared cameras used in CADs (Computer-Aided Diagnostics), which can improve medical imaging, security surveillance, and environmental monitoring, thus contributing to the well being of society. These advancements are crucial for meeting the growing demands for energy and data in our increasingly connected world, ultimately contributing to a more sustainable and technologically advanced society.
Tell us an example of a specific memorable work you did that is very close to you!
One of the most memorable moments in my career was when I received the scholarship for my Master’s and PhD at Shizuoka University and Hokkaido University in Japan. This opportunity, combined with the knowledge I gained from publishing in journals and presenting at conferences, opened doors to remarkable achievements. After arriving in Japan, I had the chance to work with some of the most brilliant minds in the field at NIMS and later at NTT Basic Research Laboratories (BRL). Being part of a team of world-class scientists was a defining moment, pushing me to continually strive for excellence. These experiences helped me shape my career and contribute to groundbreaking work in quantum materials and photodetectors.The journey from a scholarship recipient to working with renowned researchers and contributing to advancements in quantum sensing has been a truly transformative part of my professional life, and I am deeply grateful for it.
Your advice to students based on your experience?
My advice to students is this: embrace failure as part of the learning process and stay deeply curious. Research is not a straight or easy path— it’s filled with setbacks, dead-ends, and tough moments. But every failure brings a lesson, and every challenge you overcome builds the foundation of real progress. Stay committed to your goals, but stay flexible—some of the best discoveries come from unexpected results. Focus not just on grades, but on gaining true understanding and hands-on experience.
For students from financially challenged backgrounds: I know how hard it can be. I’ve walked that path too. Money is important, but it should never be the reason to give up on your dreams. Look for opportunities—scholarships, research roles, mentors, and even small openings —that might lead you forward. If you truly want to be a scientist, an engineer, or a researcher, you have to find your own route, even if it’s unconventional. It might take time, but persistence, curiosity, and belief in yourself will take you where you need to go.
Future Plans?
Looking ahead, my immediate goal is to continue advancing my research in quantum materials and photodetectors to develop more efficient and scalable technologies for energy conversion and data communication. In the long term, I aim to contribute to the broader field of quantum computing and quantum sensing, exploring new materials and methods that can push the boundaries of what is possible in these fields. I also hope to collaborate more with interdisciplinary teams, combining quantum physics with engineering to create practical solutions that address global challenges. Ultimately, I envision a future where my work in fundamental research helps shape the next generation of technologies that will have a lasting impact on society.