Purely organic single-component luminescent materials enabling multi-color photoluminescence are gaining significant interest,given their tunable optical properties,environmental friendliness,and cost-effectiveness.Ho...Purely organic single-component luminescent materials enabling multi-color photoluminescence are gaining significant interest,given their tunable optical properties,environmental friendliness,and cost-effectiveness.However,realizing multi-color electroluminescence from a single-component emitter for application in organic light-emitting diode(OLED)remains challenging,mainly due to the limitations in achieving distinct excited-state conformations in amorphous or solid states.In this study,we report two novel emitters(Bppy-PTZ and Bpph-PTZ)by incorporating a benzophenone acceptor and phenothiazine donor with pyridyl and phenylπ-bridging spacers.The introduction of a pyridine ring in Bppy-PTZ establishes intramolecular hydrogen bonding,stabilizing the quasi-axial(QA)conformation in the amorphous state,thereby facilitating multi-color and white-light emissions in thin-film and OLED devices.Photophysical and theoretical analyses reveal distinct emission behaviors from QA and quasi-equatorial conformations,with Bppy-PTZ exhibiting enhanced dual-emission and mechanochromic properties.Importantly,by adopting single-component Bppy-PTZ,the fabricated OLEDs realize color-tunable emissions,including blue,yellow,and adjustable white lights,reaching maximum external quantum efficiencies of up to 15.5%.This work provides valuable insights for the development of efficient single-component emitters affording multi-color OLEDs with high performances.展开更多
Flexible molecules have great potential for constructing multicolor luminescent materials.Understanding the relationship between conformation and luminescence and exploring strategies to regulate emissions are crucial...Flexible molecules have great potential for constructing multicolor luminescent materials.Understanding the relationship between conformation and luminescence and exploring strategies to regulate emissions are crucial for the development of flexible molecules.In this work,we designed a molecule(HTP)with multiple flexibility and realized its color-tunable emissions via vip regulation.Interestingly,HTP can adjust its conformation and adopt different arrangements with vip water molecules.Two single crystals are obtained,which show green and yellow emissions with HTP:water ratios of 2:1 and 1:1,respectively.Meanwhile,the amorphous sample without water exhibits an orange emission.Notably,the tunable triplet excited state plays an important role in the luminescence of HTP,participating in thermally activated delayed fluorescence(TADF)and room temperature phosphorescence(RTP).Further combining theoretical calculations,the relationship between the multiple flexibility and excited-state energy levels is revealed.Different flexible structures show different dominant effects on the photophysical properties.Moreover,the multicolor and stimulus-responsive luminescence property of HTP is successfully applied in the application of anti-counterfeiting and information encryption.This work demonstrates a paradigm for designing and regulating the molecule with multiple flexibility,which may broaden the understanding of the conformation-luminescence relationship and enlarge the scope of flexible molecules.展开更多
基金the National Natural Science Foundation of China(NSFC:52473195,52303250,and 52073316)Guangdong Basic and Applied Basic Research Foundation(2022B1515020052)Research Foundation of the Department of Education of Guangdong Province(2024KCXTD009).
文摘Purely organic single-component luminescent materials enabling multi-color photoluminescence are gaining significant interest,given their tunable optical properties,environmental friendliness,and cost-effectiveness.However,realizing multi-color electroluminescence from a single-component emitter for application in organic light-emitting diode(OLED)remains challenging,mainly due to the limitations in achieving distinct excited-state conformations in amorphous or solid states.In this study,we report two novel emitters(Bppy-PTZ and Bpph-PTZ)by incorporating a benzophenone acceptor and phenothiazine donor with pyridyl and phenylπ-bridging spacers.The introduction of a pyridine ring in Bppy-PTZ establishes intramolecular hydrogen bonding,stabilizing the quasi-axial(QA)conformation in the amorphous state,thereby facilitating multi-color and white-light emissions in thin-film and OLED devices.Photophysical and theoretical analyses reveal distinct emission behaviors from QA and quasi-equatorial conformations,with Bppy-PTZ exhibiting enhanced dual-emission and mechanochromic properties.Importantly,by adopting single-component Bppy-PTZ,the fabricated OLEDs realize color-tunable emissions,including blue,yellow,and adjustable white lights,reaching maximum external quantum efficiencies of up to 15.5%.This work provides valuable insights for the development of efficient single-component emitters affording multi-color OLEDs with high performances.
基金supported by the National Natural Science Foundation of China(52303250,52073316)the Guangdong Basic and Applied Basic Research Foundation(2022B1515020052)。
文摘Flexible molecules have great potential for constructing multicolor luminescent materials.Understanding the relationship between conformation and luminescence and exploring strategies to regulate emissions are crucial for the development of flexible molecules.In this work,we designed a molecule(HTP)with multiple flexibility and realized its color-tunable emissions via vip regulation.Interestingly,HTP can adjust its conformation and adopt different arrangements with vip water molecules.Two single crystals are obtained,which show green and yellow emissions with HTP:water ratios of 2:1 and 1:1,respectively.Meanwhile,the amorphous sample without water exhibits an orange emission.Notably,the tunable triplet excited state plays an important role in the luminescence of HTP,participating in thermally activated delayed fluorescence(TADF)and room temperature phosphorescence(RTP).Further combining theoretical calculations,the relationship between the multiple flexibility and excited-state energy levels is revealed.Different flexible structures show different dominant effects on the photophysical properties.Moreover,the multicolor and stimulus-responsive luminescence property of HTP is successfully applied in the application of anti-counterfeiting and information encryption.This work demonstrates a paradigm for designing and regulating the molecule with multiple flexibility,which may broaden the understanding of the conformation-luminescence relationship and enlarge the scope of flexible molecules.
