11. Light striking the sensitiser excites electrons which are absorbed by the titania to become an electric current. 12. This means that there are more excited electrons than electrons in the lowest energy state in the system. 13. This absorption happens when two atoms collide with each other while one of them has an excited electron . 14. The wavefunction of the bound state is said to be " effective masses of the excited electron and hole. 15. When sunlight ( photons ) strike PV cells, they excite electrons and allow them to flow, creating an electric current. 16. The excited electron and hole can recombine and release the energy gained from the excitation of the electron as heat. 17. After some time delay, a second, higher energy pulse photoemits the excited electron into free electron states above the vacuum level. 18. The first one corresponds to the superconducting ground state and the next to the thermally excited electrons from the ground state. 19. Furthermore, the excited electron is quantum entangled to another electron so it is simultaneously in both the singlet and triplet states. 20. As electron releases energy ( e . g . phonon ) it interacts with another excited electron to release its energy too.
