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This is the first review paper focusing on acenaphthylene (AN), an important building block of many organic semiconductors. We summarize the most important literature on π-conjugated AN derivatives, both small molecules and polymers, highlighting the synthetic approach and notable chemical modifications used in design of organic electronic materials. We also discuss the electronic structure and aromaticity of AN and notable device applications of AN derivatives. We expect this review to guide the further design of AN-based organic semiconductors for various optoelectronic devices.

Visible light as an excitation source has less phototoxicity toward health, and more accessibility for practical applications as compared to ultraviolet light does. However, obtaining visible-light-excited afterglow materials based on carbon dots is a formidable challenge as such materials have not emerged thus far. Herein, visible-light-excited thermally-activated delayed fluorescence combined with phosphorescence were achieved by embedding green emissive carbon dots (G-CDs) with an ultra-high quantum yield in the matrix of boron oxide. G-CDs were synthesized via the hydrothermal pyrolysis of rhodamine B in the aqueous solution of NaOH. The ultra-long afterglow can last for 13 s after the removal of the excitation source (UV or visible light). The afterglow lifetime of the G-CD/B 2 O 3 composite at the emission wavelength of 480 nm is 477.96 ms at room temperature, and 805.94 ms at 273 K. Given these features, information security, afterglow projection and photo writing were successfully realized in the G-CD/B 2 O 3 composite-based materials using a cellphone or electric torch light as a light source.

As the most successful end-capped unit in conventional A–D–A type non-fullerene acceptors (NFAs), 1,1-dicyanomethylene-3-indanone (IC) plays a significant role in enhancing the power conversion efficiencies (PCEs) of organic solar cells (OSCs). Here, an A 2 –A 1 –D–A 1 –A 2 type NFA of TP28 , containing the bridge unit of thieno[3,4- b ]pyrazine (TP) and the terminal unit of IC, is designed and synthesized. This is the first time that IC groups are introduced into the A 2 –A 1 –D–A 1 –A 2 type NFAs. By selecting four kinds of common electron-withdrawing units including benzothiadiazole (BT), quinoxaline (Qx), benzo[ d ][1,2,3]triazole (BTA) and TP, we found that the steric hindrance of the A 1 unit may be the key factor in controlling the condensation reaction and only the TP unit could obtain the target molecule. Although the electron-donating capability of the central fluorene unit is relatively weak, TP28 exhibits a quite narrow optical bandgap of 1.47 eV. The PBDB-T : TP28 photovoltaic devices demonstrate a moderate PCE of 5.31%, revealing great potential of such kind of NFA for highly efficient bulk-heterojunction (BHJ) OSCs.

Antiferroelectric materials with higher electric field, reduced energy dissipation and lower remanent polarization generally display excellent energy storage performance. In this work, Pb 0.98 La 0.02 (Hf x Sn 1? x ) 0.995 O 3 lead-based antiferroelectric ceramics were synthesized by a rolling process. It is revealed that the inhomogeneous distribution of Sn 4+ can disorder the local structure, which is responsible for the slim hysteresis loops. Superior energy storage performance (recoverable energy density W rec = 7.63 J cm ?3 , η = 94% at an electric field of 380 kV cm ?1 ) with excellent thermal stability (20–120 °C) were achieved in Pb 0.98 La 0.02 (Hf 0.45 Sn 0.55 ) 0.995 O 3 ceramic. In addition, it also shows a notable discharge current density of 1430 A cm ?2 and high level of power density of 193 MW cm ?3 with a fast discharge speed (112 ns discharge period), which greatly promote the application of this series of component materials in energy storage applications.

A series of four-coordinated Pt II (C^N)(N-donor ligand)Cl-type complexes have been synthesized through combination between C^N-type and N-donor ligands with different sizes. Photophysical features, electrochemical behaviors and electroluminescent (EL) performances have been investigated in detail. Critically, the relationship between the size of organic ligands and aggregation-induced phosphorescence emission (AIPE) behaviors for these Pt II (C^N)(N-donor ligand)Cl-type complexes has been characterized. With extending the dimensions of the C^N-type and/or N-donor ligands, the AIPE of these Pt II (C^N)(N-donor ligand)Cl-type complexes is more likely to show up with lower H 2 O volumetric fractions ( f w ) in the THF solution of these complexes. These unique AIPE experimental results have clearly revealed a new AIE mechanism called restrained D 2d deformation of the coordinating skeleton of these Pt II (C^N)(N-donor ligand)Cl-type complexes from square-planar ( D 4h ) in the ground states to the tetrahedron ( T d ) skeleton in the excited states. In addition, solution-processed organic light-emitting diodes (OLEDs) based on these AIPE emitters have been fabricated to characterize their EL potential. Impressive EL efficiencies with the maximum external quantum efficiency ( η ext ) of 25.2%, current efficiency ( η L ) of 53.9 cd A ?1 and power efficiency ( η P ) of 43.5 lm W ?1 can be achieved, indicating great potential of these Pt II (C^N)(N-donor ligand)Cl-type AIPE emitters in the field of OLEDs. Importantly, this research has proposed a new AIE mechanism to promote the development of new phosphorescent AIPE complexes with great potential in the field of OLEDs.

Constructing two dimensional (2D) van der Waals (vdW) heterostructures and understanding their electronic properties are pivotal for developing novel electronic devices. In this work, by using the first-principles calculations, we theoretically demonstrate that the 2D GaSe/GeS van der Waals (vdW) heterobilayer is a robust type-II band alignment semiconductor with a direct band gap of 1.8 eV. It exhibits a remarkable absorbance coefficient of ～10 5 cm ?1 from the UV to visible light region and a high carrier mobility with anisotropic character. The photoelectric conversion efficiency (PCE) shows a tremendous enhancement under external strain, and shows an efficiency of up to ～16.8% at 2% compressive strain. Besides, we find that applying an external electric field can effectively modulate its band gap and band offset. Interestingly, a larger external electric field can induce nearly free electron (NFE) states around the conduction band minimum (CBM) in the GaSe/GeS heterobilayer, which leads to the band transition from a semiconductor to metallic status. These results indicate that 2D GaSe/GeS heterostructures will have widespread application prospects in future photovoltaic and optoelectric nanodevices.

A new bipolar host material based on carbazole and dimesitylboron moieties, 3,6-bis(dimesitylboryl)-9-(4-(dimesitylboryl)phenyl) carbazole ( BDDPC ), has been successfully synthesised and characterised by elemental analysis, nuclear magnetic resonance spectroscopy, mass spectrometry and thermogravimetric analysis. The electrochemical and photophysical properties of BDDPC are studied by both experimental and theoretical methods. BDDPC exhibits excellent thermal stability ( T d = 234 °C), electrochemical stability, high fluorescence quantum yield (0.95) and high triplet energy (2.83 eV). A red phosphorescent organic light-emitting diode (PhOLED) device comprising BDDPC as the host material and Os(bpftz) 2 (PPh 2 Me) 2 as the dopant is fabricated and displays promising electrophosphorescence properties with a turn-on voltage of 3.0 V, a maximum brightness of 12?337 cd m ?2 and a maximum current efficiency of 11.04 cd A ?1 . Similarly, BDDPC is used to fabricate a green PhOLED device with Ir(ppy) 2 (acac) as the dopant, possessing a turn-on voltage of 2.5 V, a maximum brightness of 26?473 cd m ?2 and a maximum current efficiency of 38.60 cd A ?1 . Furthermore, a blue PhOLED device with BDDPC as the host material and FIrpic as the dopant is fabricated with a turn-on voltage of 3.0 V, a maximum brightness of 7622 cd m ?2 and a maximum current efficiency of 7.39 cd A ?1 . It is anticipated that BDDPC has great potential in manufacturing PhOLED devices for display or lighting applications.

We report the synthesis and comparative study of five conjugated polymers P1–P5 with different arrangements of two solubilizing 2-ethylhexyl side chains in their repeating units. It has been shown that positioning of the alkyl substituents affects strongly frontier energy levels of the polymers and results in variation of their optical band gaps between 1.65 and 2.0 eV. The highest (2.8 × 10 ?4 cm 2 V ?1 s ?1 ) and the lowest (2.4 × 10 ?5 cm 2 V ?1 s ?1 ) charge carrier mobilities determined for the polymers P1 and P5 , respectively, using a SCLC technique differ by more than one order of magnitude. GIWAXS measurements also revealed very different degrees of molecular ordering in the films of polymers P1–P5 which correlate well with the SCLC mobility data and solid state photoluminescence spectra of these materials. The bulk heterojunction solar cells based on the composites of polymers P1–P5 with [60]PCBM demonstrated power conversion efficiencies ranging from 0.6% ( P5 ) to 5.1% ( P1 ) thus evidencing a strong influence of the alkyl side chains on the photovoltaic performance of the designed polymer-based materials.

Compared with noble metals, semiconductors have been gradually exploited more as another type of SERS substrate materials due to their distinctive advantages. However, an inferior enhancement factor (EF) is a fatal weakness of the semiconductors. So, we combined the strong LSPR coupling between Ag particles and the charge transport channels induced by Mg doping to create a high performance SERS substrate. These magnesium-doped zinc oxide–Ag nanoparticles (ZMOA) exhibited 18 times higher SERS enhancement than when the SERS spectra of 4-MPY was collected on Ag, 30 times higher than magnesium-doped zinc oxide (ZMO), and 121 times higher than ZnO. The formation mechanism and the enhancement mechanism of this substrate were meticulously analyzed and finite difference time domain simulations were used to examine “hot spot” distribution. By using the ZMOA, we could easily achieve the detection limit for malachite green (MG) residue as low as 10 ?13 M with a good linear relationship ( R 2 = 0.9914) between the intensity of the SERS signal and the logarithm of the MG concentration, indicating the potential application of the ZMOA substrate in quantitative determination. Also, we employed the proposed ZMOA substrate and established the analytical method for quantitative determination of the residue of MG in fish. The excellent reproducibility, long-term stability, and accuracy of detection make ZMOA a promising substrate for practical detection of contaminants. To the best of our knowledge, this is the first time that remarkable SERS activity has been observed within a hybrid semiconductor, which could open new frontiers for developing highly sensitive and stable SERS technology and has great potential applications in the areas of pesticide residue monitoring, food security, and biotechnology.

Excess iron ions are harmful to human health; therefore, it is essential to develop efficient methods to detect Fe 3+ . Herein, a new aggregation-induced emission (AIE) ligand ( L ), 4,4′-((9 H -fluoren-9-ylidene)-methylene)dipyridine, was successfully synthesized and applied to construct a luminescent Cd( II )–organic framework [Cd(NDA)(L)(H 2 O) 2 ] n ( 1 ) with a two-dimensional architecture ( H 2 NDA = 1,4-naphthalenedicarboxylic acid). Specially, 1 possesses good water stability and exhibits superior luminescence enhancement (“turn-on”) sensing of Fe 3+ with high sensitivity and selectivity in a water suspension. This represents the first example of a LMOF-based “turn-on” Fe 3+ sensor in aqueous medium.