The headlight bulb includes at least one lamp body, at least one luminous element enclosed within the at least one lamp body, a lamp base in which the at least one lamp body is fixed and power connectors for supply of energy to the at least one luminous element. The solar cell may include a photoelectric conversion layer formed of a p-type material including an organic material and an n-type material including organic nanowires. This realizes a practical CVD apparatus for mass production which achieves both a high film deposition efficiency and high film quality.