Thermally activated delayed fluorescence(TADF)exciplexes,constituted of donor-acceptor moieties,have garnered mounting interest because of their promising potential to obtain high-performance electroluminescent device...Thermally activated delayed fluorescence(TADF)exciplexes,constituted of donor-acceptor moieties,have garnered mounting interest because of their promising potential to obtain high-performance electroluminescent devices.However,the moderate reverse intersystem crossing(RISC)of current reported exciplex systems and the lack of clear molecular design concepts to improve this situation have distinctly hindered the further use of exciplexes in organic light-emitting diodes(OLEDs).Herein,we conduct an exploration of exciplex systems founded upon[2,2]paracyclophane(PCP)-containing donor molecules and a triazine acceptor,which exhibit very fast RISC processes with a rate constant(k_(RISC))up to 8.3×10^(6) s^(-1)benefiting from the efficient interactions between the donor and acceptor fragments induced by the peripheral spatial-blocking of PCP group.Utilizing these deep-blue exciplexes as hosts and a multiple resonance(MR)molecule as emitter,pure-blue narrowband OLEDs with CIE coordinates of(0.124,0.137),a full-width at half-maximum(FWHM)of 23 nm,and a high external quantum efficiency(EQE)of around 30%are accessed.This study paves the way for developing blue OLEDs using PCP-based exciplex materials with an enhanced RISC process.展开更多
The development of cost-effective,environmentally sustainable narrowband near-infrared(NIR)organic light-emitting diodes(OLEDs)remains challenging due to low intrinsic quantum yields of NIR emitters,as constrained by ...The development of cost-effective,environmentally sustainable narrowband near-infrared(NIR)organic light-emitting diodes(OLEDs)remains challenging due to low intrinsic quantum yields of NIR emitters,as constrained by the energy gap law and inefficient triplet exciton utilization.In this study,we present a conformation-locking strategy combined with donor engineering to enhance NIR emitters based on a boron-dipyrromethene(BODIPY)scaffold for high-performance solution-processed OLEDs.Two NIR emitters,Ph-BDP-Cz and Ph-BDP-PY,were synthesized by introducing a donor at the α-position of the BODIPY core via a vinyl bridge.This design increases molecular rigidity by promoting HF interactions between vinyl hydrogens and the BF2 group,suppressing twisting and scissoring motions,which results in narrow emission and high photoluminescence quantum yields.Donor engineering also enables fine-tuning of emission wavelengths without broadening the full-width at half-maximum(FWHM),maintaining a narrow emission profile.Using these BODIPY emitters in thermally activated delayed fluorescence(TADF)-sensitized hyperfluorescent OLEDs,we achieved a maximum external quantum efficiency(EQE)of 6.9%with an emission peak at 702 nm and a narrow FWHM of<45 nm.To our knowledge,this represents one of the highest efficiencies among TADF sensitized solution-processed NIR OLEDs,offering a promising path toward the development of sustainable and high-performance NIR optoelectronic devices.展开更多
基金supported by the National Key R&D Program of China(2022YFE0109000)the National Natural Science Foundation of China(21975152,92256304,U23A20593)+1 种基金the China Postdoctoral Science Foundation(2022M722028)the Deutsche Forschungsgemeinschaft(DFG)under Germany’s Excellence Strategy(3DMM2O-EXC-2082/1-390761711)。
文摘Thermally activated delayed fluorescence(TADF)exciplexes,constituted of donor-acceptor moieties,have garnered mounting interest because of their promising potential to obtain high-performance electroluminescent devices.However,the moderate reverse intersystem crossing(RISC)of current reported exciplex systems and the lack of clear molecular design concepts to improve this situation have distinctly hindered the further use of exciplexes in organic light-emitting diodes(OLEDs).Herein,we conduct an exploration of exciplex systems founded upon[2,2]paracyclophane(PCP)-containing donor molecules and a triazine acceptor,which exhibit very fast RISC processes with a rate constant(k_(RISC))up to 8.3×10^(6) s^(-1)benefiting from the efficient interactions between the donor and acceptor fragments induced by the peripheral spatial-blocking of PCP group.Utilizing these deep-blue exciplexes as hosts and a multiple resonance(MR)molecule as emitter,pure-blue narrowband OLEDs with CIE coordinates of(0.124,0.137),a full-width at half-maximum(FWHM)of 23 nm,and a high external quantum efficiency(EQE)of around 30%are accessed.This study paves the way for developing blue OLEDs using PCP-based exciplex materials with an enhanced RISC process.
基金financially supported by Natural Science Foundation of Guangdong Province(No.2022B1515020041)National Natural Science Foundation of China(Nos.22350410384,52273179,52303228,U23A20594)+1 种基金Guangzhou Basic and Applied Basic Research(No.2023A04J1374)the Instrumental Analysis Center of Guangdong University of Technology for their support。
文摘The development of cost-effective,environmentally sustainable narrowband near-infrared(NIR)organic light-emitting diodes(OLEDs)remains challenging due to low intrinsic quantum yields of NIR emitters,as constrained by the energy gap law and inefficient triplet exciton utilization.In this study,we present a conformation-locking strategy combined with donor engineering to enhance NIR emitters based on a boron-dipyrromethene(BODIPY)scaffold for high-performance solution-processed OLEDs.Two NIR emitters,Ph-BDP-Cz and Ph-BDP-PY,were synthesized by introducing a donor at the α-position of the BODIPY core via a vinyl bridge.This design increases molecular rigidity by promoting HF interactions between vinyl hydrogens and the BF2 group,suppressing twisting and scissoring motions,which results in narrow emission and high photoluminescence quantum yields.Donor engineering also enables fine-tuning of emission wavelengths without broadening the full-width at half-maximum(FWHM),maintaining a narrow emission profile.Using these BODIPY emitters in thermally activated delayed fluorescence(TADF)-sensitized hyperfluorescent OLEDs,we achieved a maximum external quantum efficiency(EQE)of 6.9%with an emission peak at 702 nm and a narrow FWHM of<45 nm.To our knowledge,this represents one of the highest efficiencies among TADF sensitized solution-processed NIR OLEDs,offering a promising path toward the development of sustainable and high-performance NIR optoelectronic devices.
