The present invention relates to a field of organic electroluminescent materials, and more particularly to a thermally activated delayed fluorescence material and an organic light emitting diode display device.

Dominant guest luminescent materials are critical for affecting luminescent efficiency of organic light emitting diode (OLED) display devices. Generally, the luminescent guest materials used in OLED display devices are fluorescence materials. Generally, a ratio of singlet excitons to triplet excitons in the OLED display devices is 1:3, so an internal quantum efficiency (IQE) of the OLED display devices is merely 25%. Therefore, application of fluorescent electroluminescent devices is greatly limited. The phosphorescent heavy-metal complexes can achieve 100% IQE by using singlet and triplet excitons simultaneously due to the spin-orbit coupling of heavy atoms. However, the used heavy-metals are precious metals, such as iridium (Ir) or platinum (Pt). The phosphorescent heavy-metal complexes must be improved in terms of blue light materials. In addition, pure organic thermally activated delayed fluorescence materials have a lowest single-triplet level difference (ΔEST) which is relatively less than ever before, so that triplet excitons can be transformed to a singlet state by reverse intersystem crossing (RISC) and then are illuminated when jumping to a ground state transition by radiation. Therefore, single and triplet excitons can be simultaneously used and achieve 100% IQE.