A charge separation heterojunction structure which uses a fullerene polymer film
as a part of its constituent materials and which may be used to produce a solar
cellor a light emitting diode superior in durability, physical properties of electrons
and economic merits. The heterojunction structure is such a structure in which
an electron-donating electrically conductive high-polymer film and an electron-accepting
fullerene polymer film are layered between a pair of electrodes at least one of
which is light transmitting. In forming the layers, the fullerene polymer film
is identified using in particular the Raman and Nexafs methods in combination so
that upper layers are formed after identifying the polymer film.