Exciton forming substance, luminescent material using the substance, method for light emission and luminescent element, and device using the element

摘要

The invention provides a luminescent material that has a wide optimum concentration range, makes the controlling of the concentration easy in mass production processes, and makes it easy to obtain uniformity and reproducibility within the device or between the devices The invention also provides a light-emitting device using the luminescent material and a system using the light-emitting device. In addition, a light-emitting device is provided which shows good color purity, does not reduce current efficiency in the high luminance region, and does not degrade the lifetime characteristics. The luminescent material includes an exciton-forming substance and a luminescent substance. The exciton-forming substance is such that the energy level difference between the excited singlet state and the excited triplet state is 2 eV or lower. The luminescent substance is such that the energy level of the excited singlet state is equal to or lower than the energy level of the excited triplet state of the exciton-forming substance.