A series of tetraarylsilane compounds, namely p-BISiTPA (1), m-BISiTPA (2), p-OXDSiTPA (3), m-OXDSiTPA (4), are designed and synthesized by incorporating electron-donating arylamine and electron-accepting benzimidazole or oxadiazole into one molecule via a silicon-bridge linkage mode. Their thermal, photophysical and electrochemical properties can be finely tuned through the different groups and linking topologies. The para-disposition compounds 1 and 3 display higher glass transition temperatures, slightly lower HOMO levels and triplet energies than their meta-disposition isomers 2 and 4, respectively. The silicon-interrupted conjugation of the electron-donating and electron-accepting segments gives these materials the following advantages: i) relative high triplet energies in the range of 2.69–2.73 eV; ii) HOMO/LUMO levels of the compounds mainly depend on the electron-donating and electron-accepting groups, respectively; iii) bipolar transporting feature as indicated by hole-only and electron-only devices. These advantages make these materials ideal universal hosts for multicolor phosphorescent OLEDs. 1 and 3 have been demonstrated as universal hosts for blue, green, orange and white electrophosphorescence, exhibiting high efficiencies and low efficiency roll-off. For example, the devices hosted by 1 achieve maximum external quantum efficiencies of 16.1% for blue, 22.7% for green, 20.5% for orange, and 19.1% for white electrophosphorescence. Furthermore, the external quantum efficiencies are still as high as 14.2% for blue, 22.4% for green, 18.9% for orange, and 17.4% for white electrophosphorescence at a high luminance of 1000 cd m−2. The two-color, all-phosphor white device hosted by 3 acquires a maximum current efficiency of 51.4 cd A−1, and a maximum power efficiency of 51.9 lm W−1. These values are among the highest for single emitting layer white PhOLEDs reported till now.
If you can't find a tool you're looking for, please click the link at the top of the page to "Go to old article view". Alternatively, view our Knowledge Base articles for additional help. Your feedback is important to us, so please let us know if you have comments or ideas for improvement.