Every year, humanity uses 18 TW of power for its activities, equivalent to the amount of energy contained in 15 billion tonnes of crude oil. The Sun provides 10,000 times more. In the current context of energy transition, the benefits of solar energy are clear to see. At the Institut Polytechnique de Paris, scientists with complementary specialties are taking the conversion of this energy into electricity head-on, as they demonstrated on September 19, 2024, during the IP Paris Research Day dedicated to light. In their sights: greater efficiency and optimal use of photovoltaic cells.