TADF, or Thermally Activated Delayed Fluorescence, is a relatively new class of OLED emitter materials that promise efficient and long-lifetime performance without any heavy metals. TADF research started at around 2012, originally at Kyushu University in Japan and today many academic groups and several commercial companies are developing TADF materials.

The main reason companies are interested in TADF emission is that it could lead to an efficient and long-lasting blue OLED emitter - something that hasn't been yet achieved by other means (mainly - UDC's Phosphorescent OLED emitter technology). In recent years companies initiated commercial development of red, green and yellow TADF emitters as these can offer a lower cost alternative to UDC's PHOLEDs materials.