Limitation of room temperature phosphorescence efficiency in metal organic frameworks due to triplet-triplet annihilation.

ABSTRACT: The effect of triplet-triplet annihilation (TTA) on the room-temperature phosphorescence (RTP) in metal-organic frameworks (MOFs) is studied in benchmark RTP MOFs based on Zn metal centers and isophthalic or terephthalic acid linkers (ZnIPA and ZnTPA). The ratio of RTP to singlet fluorescence is observed to decrease with increasing excitation power density. Explicitly, in ZnIPA the ratio of the RTP to fluorescence is 0.58 at 1.04 mW cm^-2, but only 0.42 at (the still modest) 52.6 mW cm^-2. The decrease in ratio is due to the reduction of RTP efficiency at higher excitation due to TTA. The density of triplet states increases at higher excitation power densities, allowing triplets to diffuse far enough during their long lifetime to meet another triplet and annihilate. On

SUBMITTER: Zhao T 

PROVIDER: S-EPMC9659923 | biostudies-literature | 2022

REPOSITORIES: biostudies-literature