Beyond Global Maxima: My ISSP Journey in Berlin

Being accepted into the 2026 International Summer Student Program (ISSP) at the Helmholtz-Zentrum Berlin was one of the best pieces of news I have ever received. I still remember waking up in the middle of the night, checking my email, and reading the acceptance letter. It didn't feel real.

That same day, I started looking for flights, searching for accommodation, and, of course, preparing myself technically to successfully carry out the research project I had proposed.

As the months passed, however, my supervisor and I refined the project. Through many online discussions, we identified new ideas that could make the research more relevant and better aligned with the current state of the art in electrical characterization techniques for perovskite solar cells. At the same time, I had to deal with the practical side of moving abroad. Finding affordable accommodation in a good location turned out to be much harder than I expected. I spent months searching through dozens of student housing platforms before finally finding a place close to the city center.

Looking back now, I can say that all that preparation only scratched the surface of what it actually means to live in Berlin.

I had to adapt to sharing an apartment with people from different backgrounds, navigating Berlin's trains and subway system—forms of transportation I had rarely used in Brazil—and getting through everyday situations with only a handful of German expressions, such as Bitte, Verzeihung, Kann ich mit Karte bezahlen? ("Can I pay by card?"), or Brauchst du etwas vom Markt? (“Do you need anything from the market?)

Over time, I realized that these experiences were all connected to something much larger. Interestingly, my research helped me understand this connection.

My project explores Particle Swarm Optimization (PSO), a computational algorithm inspired by the collective behavior of bird flocks and fish schools. In PSO, a population of particles searches for the optimal solution in a multidimensional space. Each particle remembers the best solution it has found, while also being influenced by the best solution discovered by the entire swarm. 

Guided by its own momentum, individual experience, and collective knowledge, the swarm gradually converges toward an optimal solution.

I am applying this concept to identify the global maximum power point of perovskite solar cells with different material compositions. Unlike conventional photovoltaic devices, perovskite solar cells exhibit highly nonlinear electrical behavior due to ion migration within the material, leading to transient responses and long relaxation times. As a result, many existing Maximum Power Point Tracking (MPPT) algorithms suffer from excessive oscillations or become trapped in local maxima, limiting the accurate evaluation of device performance. By leveraging PSO, the goal is to develop a more robust tracking strategy capable of overcoming these limitations.

This idea also offers an interesting perspective beyond science. What we believe is the best path is not always the greatest potential we can achieve. Sometimes, we need to change direction, rethink our strategy, and explore new possibilities before reaching something truly meaningful. Scientific research follows the same principle: we constantly formulate hypotheses, test ideas, learn from failures, and adapt our approach to solve some of society's most challenging problems.

I'll leave Berlin with many lessons, but one stands out above the rest:

The path that seems optimal today may no longer be the best tomorrow. Progress requires questioning our assumptions, adapting when necessary, and remaining open to better solutions.

The pursuit of improvement never ends.