The interlayer dielectric film made of a three-dimensionally polymerized polymer is formed by polymerizing: first cross-linking molecules having three or more sets of functional groups in one molecule providing a three-dimensional structure; and a second cross-linking molecule having two sets of functional groups in one molecule providing a two-dimensional structure. The method comprises converting the input signal into drive signals for the at least four LED’s. A solution of the organic compound or its salt forms a solid photo voltaic layer on a substrate.