New carbazole- and indan-1,3-dione -based low molecular weight derivatives were synthesized and characterized by mass spectrometry and H-1 NMR spectroscopy. Thermal behaviour of the derivatives was demonstrated by thermo-gravimetric analysis and differential scanning calorimetry. The materials were found to show very high thermal stability having initial thermal degradation temperatures in the range of 398- 401 degrees C. Glass transition temperatures of the amorphous molecular materials were in the rage of 80-114 degrees C. The derivatives were tested as host materials in blue phosphorescent organic light emitting diodes with iridium(III)[bis(4,6-difluorophenyl)-pyridinato-N,C2]picolinate as the guests. One of the blue OLED devices demonstrated rather low turn-on voltage of 5.0V, a maximum luminance efficiency of 2.73 cd/A and maximum brightness of about 220 cd/m(2).