Synthesis of phosphorus dendrimers bearing chromophoric end groups: toward organic blue light-emitting diodes

Several series of phosphorus dendrimers decorated by potential fluorescent end groups (naphthalene, anthracene, and pyrene) have been synthesized. Unexpectedly, we found that it is absolutely necessary to link the fluorophore to the dendrimer through an alkyl link, and not directly through heteroelements such as oxygen or nitrogen, in order to preserve the fluorescence. One series of dendrimers from generation 1 (6 pyrene end groups) to generation 4 (48 pyrene end groups) has been tested for the elaboration of organic light-emitting diodes (OLEDs). The threshold voltage for the emission of light is high (over 20 V), however, electroluminescence is observed in all cases.