Which type of device converts light energy into electrical energy?

The device that converts light energy into electrical energy is the photovoltaic cell. Photovoltaic cells utilize the photovoltaic effect, which generates a flow of electricity when they absorb photons from sunlight. The energy from the light excites electrons in the material, typically silicon, allowing them to contribute to an electric current. This principle is fundamental in solar energy technology, making photovoltaic cells vital for applications ranging from small-scale power generation to large solar farms.

Although other devices listed—such as photodiodes, LDRs, and LEDs—are associated with light in various ways, they do not convert light energy into electrical energy in the same manner. For instance, while a photodiode can generate a small voltage when exposed to light, it is primarily designed for detecting light rather than generating power as a photovoltaic cell does. Light dependent resistors change their resistance with light intensity and can be used to measure light levels but do not convert light into electrical energy in the same context. LEDs are designed to emit light when an electrical current passes through them, functioning oppositely to the conversion process presented in the question.