Chiral luminescence materials have potential applications in the field of three-dimensional displays due to their circularly polarized luminescence(CPL)characteristics.However,the further development of circularly pol...Chiral luminescence materials have potential applications in the field of three-dimensional displays due to their circularly polarized luminescence(CPL)characteristics.However,the further development of circularly polarized organic light-emitting diodes(CP-OLEDs)needs to meet the requirements of high efficiency,high color purity,low cost,and high dissymmetry factor(gPLor gEL),chiral multiple resonance thermally activated delayed fluorescence(MR-TADF)materials are considered as candidates in these aspects.Herein,based on a pair of chiral spirofluorene precursors,two pairs of high-performance chiral MR-TADF emitters((R/S)-p-Spiro-DtBuCzB and(R/S)-m-Spiro-DtBuCzB)are developed,which exhibit strong emissions peaking at 491 and 502 nm in toluene with full-width at half-maximum values of 25 and 33 nm,respectively.In addition,small singlet–triplet energy gaps of 0.15 and 0.10 eV with high absolute photoluminescence efficiencies of 95.0%and 96.7%are observed for p-Spiro-DtBuCzB and m-Spiro-DtBuCzB molecules,respectively.OLEDs based on p-Spiro-DtBuCzB and m-Spiro-DtBuCzB display high maximum external quantum efficiencies of 29.6%and 33.8%,respectively.Most importantly,CP-OLEDs present symmetric circularly polarized electroluminescence spectra with|gEL|factors of 3.36×10^(-4)and 7.66×10^(-4)for devices based on(R/S)-p-Spiro-DtBuCzB and(R/S)-m-Spiro-DtBuCzB enantiomers,respectively.展开更多
The simultaneous achievement of chiral multiple-resonance thermally activated delayed fluorescence(MR-TADF)emitters with narrowband and circularly polarized electroluminescence(CPEL)poses a challenge.Herein,a MR-TADF ...The simultaneous achievement of chiral multiple-resonance thermally activated delayed fluorescence(MR-TADF)emitters with narrowband and circularly polarized electroluminescence(CPEL)poses a challenge.Herein,a MR-TADF emitter,Spiro-BNCz,embedding spirofluorene structure was developed and chiral separated,whose emission peaks at 528 nm in toluene with Commission Internationale de L’Eclairage coordinates of(0.26,0.69).The conjugation extension caused by embedding sulfur substituted spirofluorene on B/N framework shortens the singlettriplet energy gap and increases spin-orbital coupling matrix element.Therefore,a fast reverse intersystem crossing rate constant of 2.8×10^(6)s^(−1)and a high photoluminescence efficiency of 92%in film were achieved.The organic light-emitting diode(OLED)exhibits a maximum external quantum efficiency of 32.3%.Particularly,the circularly polarized OLEDs based on Spiro-BNCz enantiomers show symmetric CPEL with dissymmetry factors(|gEL|)≈10^(−3).展开更多
基金supported by the National Natural Science Foundation of China(92256304,U23A20593)。
文摘Chiral luminescence materials have potential applications in the field of three-dimensional displays due to their circularly polarized luminescence(CPL)characteristics.However,the further development of circularly polarized organic light-emitting diodes(CP-OLEDs)needs to meet the requirements of high efficiency,high color purity,low cost,and high dissymmetry factor(gPLor gEL),chiral multiple resonance thermally activated delayed fluorescence(MR-TADF)materials are considered as candidates in these aspects.Herein,based on a pair of chiral spirofluorene precursors,two pairs of high-performance chiral MR-TADF emitters((R/S)-p-Spiro-DtBuCzB and(R/S)-m-Spiro-DtBuCzB)are developed,which exhibit strong emissions peaking at 491 and 502 nm in toluene with full-width at half-maximum values of 25 and 33 nm,respectively.In addition,small singlet–triplet energy gaps of 0.15 and 0.10 eV with high absolute photoluminescence efficiencies of 95.0%and 96.7%are observed for p-Spiro-DtBuCzB and m-Spiro-DtBuCzB molecules,respectively.OLEDs based on p-Spiro-DtBuCzB and m-Spiro-DtBuCzB display high maximum external quantum efficiencies of 29.6%and 33.8%,respectively.Most importantly,CP-OLEDs present symmetric circularly polarized electroluminescence spectra with|gEL|factors of 3.36×10^(-4)and 7.66×10^(-4)for devices based on(R/S)-p-Spiro-DtBuCzB and(R/S)-m-Spiro-DtBuCzB enantiomers,respectively.
基金National Natural Science Foundation of China,Grant/Award Numbers:92256304,21975119,22171092。
文摘The simultaneous achievement of chiral multiple-resonance thermally activated delayed fluorescence(MR-TADF)emitters with narrowband and circularly polarized electroluminescence(CPEL)poses a challenge.Herein,a MR-TADF emitter,Spiro-BNCz,embedding spirofluorene structure was developed and chiral separated,whose emission peaks at 528 nm in toluene with Commission Internationale de L’Eclairage coordinates of(0.26,0.69).The conjugation extension caused by embedding sulfur substituted spirofluorene on B/N framework shortens the singlettriplet energy gap and increases spin-orbital coupling matrix element.Therefore,a fast reverse intersystem crossing rate constant of 2.8×10^(6)s^(−1)and a high photoluminescence efficiency of 92%in film were achieved.The organic light-emitting diode(OLED)exhibits a maximum external quantum efficiency of 32.3%.Particularly,the circularly polarized OLEDs based on Spiro-BNCz enantiomers show symmetric CPEL with dissymmetry factors(|gEL|)≈10^(−3).
