Highly Efficient Electroluminescent Materials with High Color Purity Based on Strong Acceptor Attachment onto B-N-Containing Multiple Resonance Frameworks

The development and enrichment of organic materials with narrowband emission in longer wavelength regions beyond 515 nm still remains a great challenge.Herein,a synthetic methodology for narrowband emission materials has been proposed to functionalize multiple resonance(MR)skeletons and generate a universal building block,namely,the key intermediate DtCzB-Bpin,which can be utilized to construct multifarious thermally activated delayed fluorescence(TADF)materials with high color purity through a simple one-step Suzuki coupling reaction.Based on this unique synthetic strategy,a series of efficient narrowband green TADF emitters has been constructed by localized attachment of 1,3,5-triazine and pyrimidine derivatives-based acceptors onto B–N-containing MR frameworks with 1,3-bis(3,6-di-tertbutylcarbazol-9-yl)benzene(DtCz)as the ligand.The precise modulation of the acceptor is an intelligent approach to achieve bathochromic shift and narrowband emission simultaneously.The DtCzB-TPTRZbased organic light-emitting diode(OLED)exhibits pure green emission with Commission Internationale de L’Eclairage(CIE)coordinates of(0.23,0.68),a maximum external quantum efficiency(EQE)of 30.6%,and relatively low efficiency roll-off.

Narrow-bandwidth emissive carbon dots:A rising star in the fluorescent material family

Fluorescent carbon dots(CDs)have recently become a research hotspot in multidisciplinary fields owing to their distinctive advantages,including outstanding photoluminescence properties,high biocompatibility,low toxicity,and abundant raw materials.Among the promising CDs,narrow‐bandwidth emissive CDs with high color purity have emerged as a rising star in recent years because of their significant potential applications in bioimaging,information sensing,and photoelectric displays.In this review,the state-of-the-art advances of narrow-bandwidth emissive CDs are systematically summarized,and the factors influencing the emission bandwidth,preparation methods,and applications of narrow-bandwidth emissive CDs are described in detail.Besides,existing challenges and future perspectives for achieving high-performance narrow-bandwidth emissive CDs are also discussed.This overview paper is expected to generate more interest and promote the rapid development of this significant research area.

Preparation of M_(2)B_(5)O_(9)Cl:Eu^(2+)(M=Sr,Ca)blue phosphors by a facile low-temperature self-reduction method and their enhanced luminescent properties

In this work,through a facile method of low-temperature(only 350℃)self-reduction,1D nano-sized M_(2)B_(5)O_(9)CI:Eu^(2+)(M=Sr,Ca)blue phosphors with highly efficient performance can be obtained.The crystal structure,morphology and photoluminescence(PL)properties including thermal stability of M_(2)B_(5)O_(9)CI:Eu^(2+)(M=Sr,Ca)phosphors were investigated.The M_(2)B_(5)O_(9)CI:Eu^(2+)(M=Sr,Ca)phosphors show broad band excitation spectra and narrow band emission spectra.The photoluminescence quantum yields(PLQY)of M_(2)B_(5)O_(9)CI:Eu^(2+)(M=Sr,Ca)are as high as 98%and 87.2%,respectively.Furthermore,the color purities of M_(2)B_(5)O_(9)CI:Eu^(2+)(M=Sr,Ca)can reach 99.1%and 93.2%,respectively,When heated up to 150℃,the emission intensities of M_(2)B_(5)O_(9)CI:Eu^(2+)(M=Sr,Ca)phosphors can still keep 72.7%and80.0%,respectively.Finally,the above-mentioned phosphors exhibit outstanding performance when manufacturing WLEDs.