Hitherto, research has been conducted on α-NPD, rubrene, Alq3, PBD, and the like, as a luminescent material and an organic semiconductor material used in organic light-emitting elements such as organic EL devices and organic light-emitting diodes (Patent Literature 1 to 3).
In an organic light-emitting element, a thin film including a fluorescent organic compound or a phosphorescent organic compound is sandwiched between a positive electrode and a negative electrode. The element utilizes light radiated when an exciton of the fluorescent compound or the phosphorescent compound, generated through injection of electron or hole (positive hole) from the respective electrodes, returns to a ground state.
Recent progresses regarding organic light-emitting elements have been remarkable. Since the elements have characteristics enabling realization of a lightweight and thin luminous device that has high-speed response, a diverse luminous wavelength, and high brightness when low voltage is applied thereto, a wide range of possible applications thereof is suggested.
However, presently, the output of light with further high brightness or high conversion efficiency is required. In addition, there are still many problems regarding durability, such as changes observed over time after being used for a long period of time, and deterioration due to moisture and atmosphere gas containing oxygen. Furthermore, although light emission of red, green, and blue with fine color purity is required when considering application thereof to a full-color display or the like, there has not been a sufficient answer for such problems.
Patent Literature 4 discloses a polycyclic aromatic compound having a single heteroatom in a non-aromatic ring.