Efficient Purely Organic Room-Temperature Phosphorescence from Selenium-Containing Conjugated Polymers for Signal-Amplified Oxygen Detection

Purely organic room-temperature phosphorescent (RTP) polymers with good processability and flexibility over small molecular crystals are highly attractive. Although many non-conjugated polymers (non-CPs) with efficient RTP emission have been reported, the development of metal-free RTP CPs remains a formidable challenge. Herein, CPs with clear RTP emission in both doped and neat films are readily prepared by introducing a selenium-containing phenoselenazine unit into conjugated backbones. The resulting RTP CPs can achieve phosphorescence lifetimes ranging from microseconds to milliseconds and phosphorescence quantum yields of up to 17.2% in film states, representing the highest value for metal-free CPs. Moreover, these RTP polymer films can be used for ratiometric oxygen detection due to their sensitive RTP emission to oxygen. Remarkably, for the first time, these metal-free CPs demonstrate significant phosphorescent signal amplification with a Stern–Volmer quenching constant (KSV) value of up to 5.54 × 10–3 ppm–1, which is 250 times higher than that of their molecule counterpart.