Abstract: The buffer stopper has a base and an elastic body. The base has a columnar shape having a through hole in a center thereof and having recesses at both ends (virtual surfaces including an end surface of a straight part) thereof, and is formed of a material such as a metal or resin, which is harder than a rubber-like elastic material used as a material for the elastic body. The elastic body is an integrally-molded product made of a rubber-like elastic material. The elastic body includes a pair of end elastic bodies fitted into the recesses of the base and protruding from both ends of the base and connects the pair of end elastic bodies by a central elastic body fitted into the through hole.

Abstract: [Object] A thin-film solar cell which can be produced using an inexpensive raw material and has improved conversion efficiency has been desired. [Solution] A thin-film solar cell according to the present invention includes at least one organic semiconductor and a coordination polymer. The coordination polymer contains a repeating unit which includes a complex produced by coordinating at least one ligand to at least one metal ion, the metal ion being selected from ions of transition metal elements, and the ligand being capable of coordinating to the metal ion and selected from sulfur-containing compounds, nitrogen-containing compounds, oxygen-containing compounds, and phosphorus-containing compounds.