1. Light and action, synthesized in green plants. Converting solar energy into chemical energy (starch)
2. Photothermal effect, household installed solar water heater is mainly this. Convert solar energy into heat
3. Photovoltaics, which is how most solar power plants turn the sun's energy into electricity.
Specific role is: when the light on the semiconductor pn junction, a hole for electrons, carrier has not been generated within the semiconductor junction near composite and the space charge region, attracted by the built-in electric field, electrons flowing into n area, the hole into the p area, n area to store the surplus electronic as a result, p area have excess cavitation. They form a photoelectric field near the PN junction in the opposite direction to the barrier. In addition to partially canceling the effect of the barrier electric field, the photogenerated electric field also makes the P region positively charged, and the N region negatively charged. The thin layer between the N region and the P region produces electromotive force, which is light
