An Electroactive Pure Organic Room-Temperature Phosphorescence Polymer Based on a Donor-Oxygen-Acceptor Geometry.

An electroactive room-temperature phosphorescence (RTP) polymer has been demonstrated based on a characteristic donor-oxygen-acceptor geometry. Compared with the donor-acceptor reference, the inserted oxygen atom between donor and acceptor can not only decrease hole-electron orbital overlap to suppress the charge transfer fluorescence, but also strengthen spin-orbital coupling effect to facilitate the intersystem crossing and subsequent phosphorescence channels. As a result, a significant RTP is observed in solid states under photo excitation. Most noticeably, the corresponding polymer light-emitting diodes (PLEDs) reveal a dominant electrophosphorescence with a record-high external quantum efficiency of 9.7 %. The performance goes well beyond the 5 % theoretical limit for typical fluors, opening a new door to the development of pure organic RTP polymers towards efficient PLEDs.