In this work we report the second ever example of a fully experimentally confirmed thermally activated delayed fluorescence(TADF)in a dinuclear Ir(Ⅲ)complex.The said complex displays a singlet-triplet gap ΔE_(ST)=28...In this work we report the second ever example of a fully experimentally confirmed thermally activated delayed fluorescence(TADF)in a dinuclear Ir(Ⅲ)complex.The said complex displays a singlet-triplet gap ΔE_(ST)=28±5 meV,in agreement with the computational prediction of 31.1 meV-a value smaller than the previous TADF Ir(Ⅲ)complex.We also demonstrate a proof-of-concept,solution-processed OLED featuring this complex as the luminescent dopant in the emissive layer,achieving external quantum efficiency of up to~10%and maximum luminance of 18000 cd m^(−2)-values significantly exceeding those reported earlier for Ir(Ⅲ)TADF.These findings are preceded by a detailed consideration of spectral signs of TADF in the already known Ir(Ⅲ)complexes.The spectral overlap of photoluminescence(PL)with strong(i.e.,spin-allowed)absorption bands is unusual for phosphorescent metal complexes,because the PL originates from the triplet state,which is normally significantly lower in energy than the lowest-lying singlet.In this study,we have scrutinized literature data on iridium(Ⅲ)complexes that likewise show significant overlap between absorption and PL,and we conclude that a small singlet-triplet energy gap ΔE_(ST) in these complexes results in a TADF contribution to their emission.Such a mechanism has hitherto been overlooked in the large body of iridium(Ⅲ)chemistry.We use computations to clarify the nature of the excited states in these complexes,demonstrating that the distinctive S_(1) and T_(1) character of states can be identified as well as confirming that ΔE_(ST) is small enough for TADF to occur at room temperature.展开更多
In this paper,a method to excite chiral quasi-bound states in the continuum(Q-BICs)using an asymmetric interface is proposed for the first time,to our knowledge.The chirality of a metasurface can be controlled by vary...In this paper,a method to excite chiral quasi-bound states in the continuum(Q-BICs)using an asymmetric interface is proposed for the first time,to our knowledge.The chirality of a metasurface can be controlled by varying the medium of the active layer,achieving a maximum circular dichroism(CD)value of 0.9.Two types of reconfigurable chiral Q-BIC metasurfaces,a single-biased chiral Q-BIC metasurface(SBCBM)and a dual-biased chiral Q-BIC metasurface(DBCBM),are proposed,facilitated by the use of the electronically controlled material polyaniline(PANI).This enables electrically reconfigurable chiral Q-BIC with a maximum CD variability range from-0.9 to+0.9.These results highlight significant potential applications in fields such as reconfigurable devices,optical chiral switching,and environmental monitoring.展开更多
基金the National Science Centre,Poland for funding,grant no.2022/45/B/ST4/02689.
文摘In this work we report the second ever example of a fully experimentally confirmed thermally activated delayed fluorescence(TADF)in a dinuclear Ir(Ⅲ)complex.The said complex displays a singlet-triplet gap ΔE_(ST)=28±5 meV,in agreement with the computational prediction of 31.1 meV-a value smaller than the previous TADF Ir(Ⅲ)complex.We also demonstrate a proof-of-concept,solution-processed OLED featuring this complex as the luminescent dopant in the emissive layer,achieving external quantum efficiency of up to~10%and maximum luminance of 18000 cd m^(−2)-values significantly exceeding those reported earlier for Ir(Ⅲ)TADF.These findings are preceded by a detailed consideration of spectral signs of TADF in the already known Ir(Ⅲ)complexes.The spectral overlap of photoluminescence(PL)with strong(i.e.,spin-allowed)absorption bands is unusual for phosphorescent metal complexes,because the PL originates from the triplet state,which is normally significantly lower in energy than the lowest-lying singlet.In this study,we have scrutinized literature data on iridium(Ⅲ)complexes that likewise show significant overlap between absorption and PL,and we conclude that a small singlet-triplet energy gap ΔE_(ST) in these complexes results in a TADF contribution to their emission.Such a mechanism has hitherto been overlooked in the large body of iridium(Ⅲ)chemistry.We use computations to clarify the nature of the excited states in these complexes,demonstrating that the distinctive S_(1) and T_(1) character of states can be identified as well as confirming that ΔE_(ST) is small enough for TADF to occur at room temperature.
基金National Natural Science Foundation of China(61205095)。
文摘In this paper,a method to excite chiral quasi-bound states in the continuum(Q-BICs)using an asymmetric interface is proposed for the first time,to our knowledge.The chirality of a metasurface can be controlled by varying the medium of the active layer,achieving a maximum circular dichroism(CD)value of 0.9.Two types of reconfigurable chiral Q-BIC metasurfaces,a single-biased chiral Q-BIC metasurface(SBCBM)and a dual-biased chiral Q-BIC metasurface(DBCBM),are proposed,facilitated by the use of the electronically controlled material polyaniline(PANI).This enables electrically reconfigurable chiral Q-BIC with a maximum CD variability range from-0.9 to+0.9.These results highlight significant potential applications in fields such as reconfigurable devices,optical chiral switching,and environmental monitoring.
