An asymmetric molecule created by molecular heredity exhibits remarkable mechanochromism and white-light emission.

Two heavy atom-free white-light emitting luminophores exhibit fluorescence–phosphorescence dual-emission and are multi-stimuli responsive at room temperature.

Actualizing full singlet exciton yield via a reverse intersystem crossing from the high‐lying triplet state to singlet state, namely, “hot exciton” mechanism, holds great potential for high‐performance fluorescent organic light‐emitting diodes (OLEDs). However, incorporating comprehensive insights into the mechanism and effective molecular design strategies still remains challenging. Herein, three blue emitters (CNNPI, 2TriPE‐CNNPI, and 2CzPh‐CNNPI) with a distinct local excited (LE) state and charge‐transfer (CT) state distributions in excited states are designed and synthesized. They show prominent hybridized local and charge‐transfer (HLCT) states and aggregation‐induced emission enhancement properties. The “hot exciton” mechanism based on these emitters reveals that a balanced LE/CT distribution can simultaneously boost photoluminescence efficiency and exciton utilization. In particular, a nearly 100% exciton utilization is achieved in the electroluminescence (EL) process of 2CzPh‐CNNPI. Moreover, employing 2CzPh‐CNNPI as the emitter, emissive dopant, and sensitizing host, respectively, the EL performances of the corresponding nondoped pure‐blue, doped deep‐blue, and HLCT‐sensitized fluorescent OLEDs are among the most efficient OLEDs with a “hot exciton” mechanism to date. These results could shed light on the design principles for “hot exciton” materials and inspire the development of next‐generation high‐performance OLEDs.

Combining HLCT and AIE characteristics, six phenanthroimidazole derivatives were designed with different patterns for high-efficiency non-doped OLEDs.

Ultralong organic room-temperature phosphorescence (RTP) materials have attracted great attention recently due to its diverse application potentials. Several ultralong organic RTP materials mimicking the host-guest architecture of inorganic systems have been exploited successfully. However, complicated synthesis and high expenditure are still inevitable in these cases. Herein, we develop a series of novel host-guest organic phosphore systems, in which all chromophores are electron-rich, commercially available and halogen atom free. The maximum phosphorescence efficiency and the longest lifetime reach at 23.6% and 362 ms, respectively. Most importantly, experimental results and theoretical calculation indicate that the host molecules not only play a vital role in providing a rigid environment to suppress non-radiative decay of the guest, but also show a synergistic effect to the guest through Förster energy transfer (FERT). The commercial availability, facile preparation and unique properties also make these new host-guest materials an excellent candidate for anti-counterfeiting devices. File list (3) download file view on ChemRxiv Manuscript-20201025.docx (0.94 MiB) download file view on ChemRxiv Manuscript-20201025.pdf (770.76 KiB) download file view on ChemRxiv Supporting Information-20201025.docx (1.53 MiB)

By combining aggregation-induced emission (AIE) effect and triplet-triplet upconversion (TTU) process, a blue emitter with excellent photoluminescence quantum efficiency and high upconversion efficiency in the film state is developed, from...

With the advent of the big data era, information storage and security are becoming increasingly important. However, high capacity information storage and multilevel anti-counterfeiting are typically difficult to simultaneously achieve....

charge transfer (ICT) states which depend on the electronic nature and the connecting patterns of donors (D) and acceptors (A). In most cases, the large torsion between D and A results in small overlapping of frontier orbitals and is detrimental to radiative decay process. [5] Furthermore, the structure would be strong polarized and twisted by polar solvent, so the elevation of highest occupied molecular orbital (HOMO) level and narrowing the bandgap, generates the redshift in its photoluminescence spectrum. [6] For achieving strong emission of D-A molecules, some ICT materials are constructed by D-π-A mode instead of D-A type for preventing serious distortion, and their OLEDs performance would be improved obviously. [7] Klymchenko et al. replaced naphthalene core by fluorene to extend electronic conjugation and FR0(7-diethylamino-9,9′-dimethyl-9Hfluorene-2-carbaldehyde) still exhibits strong fluorescence and large stokes shift in high polar solvents. [8] Konishi et al. inhibited the distortion of biphenyl unit through bonding methylene-and ethylene-bridge on dimethylaniline-benzaldehyde derivatives. [6] Recently, Haberhauer et al. proposed the model of planarized intramolecular charge transfer (PLICT) states that the conformations are flatter in their excited states than these in ground In contrast to the common intramolecular charge transfer (ICT) emission, planarized intramolecular charge transfer (PLICT) based materials usually possess higher proportion radiative decay for their flat and rigid conformation in excited states. Herein, a strategy for designing PLICT-based emitters by the excited state quinone-conformation induced planarization is proposed. By virtue of RIR mechanism on TPP (tetraphenylpyrazinyl) unit, the newcomers named as TPP-PPI (1-phenyl-2-(4′-(3,5,6-triphenylpyrazin-2-yl)-[1,1′-biphenyl]-4-yl)-1H-phenanthro[9,10-d] imidazole) and TPP-PI (1-phenyl-2-(4-(3,5,6triphenylpyrazin-2-yl)phenyl)-1H-phenanthro[9,10-d]imidazole) exhibit aggregation-induced emission (AIE) characteristics. TPP-PPI and TPP-PI have obvious PLICT properties via series of spectral measurements. Employing theoretical calculation in ground and excited states in different solvents, their PLICT process is confirmed further, and TPP's contribution on PLICT formation becomes clear. In non-doped organic light-emitting diodes, these two emitters with AIE and PLICT characteristic exhibit good performance with external quantum efficiency (4.85% and 4.36%) as blue emitters.