Chalcogen Effect of Atom Substitution on the Properties of Tris(2,4,6-trichlorophenyl)methyl(TTM)Radical

Luminescent open-shell organic radicals have recently been regarded as one of the most potential materials in organic light-emitting diodes(OLEDs).Herein,we have synthesized two new organic radicals,namely tris{4-[4-(tert-butyl)phenoxy]-2,6-dichlorophenyl}methane radical(TTM-O)and tris(4-{[4-(tert-butyl)-phenyl]thio}-2,6-dichlorophenyl)methane radical(TTM-S),by the substitution of chalcogen atom elements at the para position of conventional tris(2,4,6-trichlorophenyl)methyl(TTM)radical moiety.Interestingly,both TTM-O and TTM-S exhibited significantly enhanced photostability compared with the unsubstituted TTM radical parent.Moreover,the chalcogen atom also had a crucial impact on the photoluminescence quantum yield(PLQY)of the radicals,i.e.,the PLQY of TTM-S was greatly enhanced compared to TTM radical while TTM-O was nearly non-emissive.Particularly,TTM-S showed intense PLQY of 37.54%and 185-fold longer photostability than that in cyclohexane solution of TTM.