New high efficiency blue light-emitting phosphorescent devices using the mixed host of p-bis(triphenylsilyl)-benzene [UGH2] and carbazole derivative like 4,4',4 ''-tris(N-carbazolyl)-triphenylamine [TCTA] or N,N'-dicarbazolyl-3,5-benzene [mCP] and the dopant of 10% bis((3,5-difluoro-4-cyanophenyl) pyridine) iridium-picolinate [FCNIr(pic)] were fabricated and evaluated according to the different treatments of carbazolyl materials and the mixture ratios of TCTA/UGH2. The best result was obtained in the mixed host of UGH2 and 10% TCTA. In the devices with the mixed host of UGH2 and 10% TCTA, the addition of two exciton blocking layers of mCP and tris-[3-(3-pyridyl)mesityl]borane [3TPYMB] resulted in the improvement of current efficiency and color quality. The device with organic structure of N,N'-diphenyl-N,N'-bis-[4-(phenyl-m-tolylamino)-phenyl]-biphenyl-4,4'-diamine [DNTPD]/N,N'-di(1-naphthyl)-N,N'-diphenylbenzidine [NPB]/mCP/(UGH2, 10% TCTA) doped with 10% FCNIr(pic)/3TPYMB/4,7-diphenyl-1,10-phenanthroline [Bphen] showed the maximum current efficiency of 9.5 cd/A and color coordinates of (0.16, 0.24) on the Commission Internationale de I' Eclarirage (CIE) chart.