Piezochromic luminescent materials with multi-color switching have recently attracted much attention owing to their appealing applications in the field of advanced photonics, such as optical recording, memory and sensors. Mechanical grinding and diamond anvil cell (DAC) devices are two common ways to investigate piezochromic materials. This review comprehensively summarizes the recent progress of piezochromic materials and their behaviours under hydrostatic pressure generated from DAC, in particular, different types of organic piezochromic materials. We describe their spectroscopic phenomena, discuss corresponding mechanisms, and intend to find the inherent clues hidden in the scattered literature.

In recent years, the lead-free zero-dimensional (0D) perovskite nanocrystals (NCs) with isolated octahedral structure have attracted wide attentions due to their unique photoelectric properties, such as the excellent absorption cross-sections, large exciton binding energy and low carrier mobility. However, the emitting wavelength of the lead-free 0D perovskite NCs can only be modulated in the green and blue spectral region. Until now, how to realize the red and white emission in the lead-free 0D perovskite NCs is still a challenge. In this work, the leadfree 0D K3SbCl6 perovskite NCs were firstly developed by the hot injection synthesis method. Through controlling the synthetic temperature, the as-prepared NCs exhibit the blue emission centered at 440 nm with the highest photoluminescence quantum yield (PLQY) of 22.3%. Furthermore, the Mn2+ ions were further doped into 0D lead-free K3SbCl6 perovskite NCs, leading to the additional red light emission attributed to the intrinsic transition (T-4(1)-(6)A(1)) of Mn2+ ions. By controlling the Mn2+ ion doping concentration, the white light emission with PLQY of 37.2% was realized. Finally, the white light emitting devices (WLEDs) with the Commission Internationale de L?Eclairage 1931(CIE) of (0.29, 0.28), (0.32, 0.30) and (0.35, 0.30) were fabricated by combining the as-prepared Mn2+-K3SbCl6 perovskite NCs with commercial 365 nm UV light chips. The white light performances of the as-fabricated WLEDs were modulated with tunable correlated color temperature (CCT) from 8173 to 4779 K, which exhibit the high color-rendering index (CRI) more than 80. These results provide the opportunity for the future applications of 0D lead-free perovskite NCs in the lighting and lasing field of LEDs.

A novel halogen bond-based co-crystal, 4,4'-trimethylenedipyridine/1,4-diiodotetrafluorobenzene (TMDP-DITFB), was achieved, which displays distinct piezochromic luminescence from none to a broad emission band (500-700 nm) assigned to the new intermolecular charge transfer (CT) state caused by the enhanced I...N interactions between TMDP and DITFB. Interestingly, once the pressure was released to the ambient condition, the emission of TMDP-DITFB could not be restored to initial state, but exhibited a new red maximum emission band at 668 nm, which is different from most piezochromic materials. Almost no change for the TMDP crystal was observed during the compression-decompression cycle. Comparative analysis between TMDP and TMDP-DITFB demonstrates that irreversible changes in fluorescence are highly related to intermolecular interactions between TMDP and co-formers modulated by pressure. Pressure-induced enhanced and irreversible emission of organic materials is rarely reported. This work enables deeper understanding on the structure-property relationship and put forward a new strategy to realize new properties of materials.

Structural changes in the trans-azobenzene single crystal and powder upon compression realized by a diamond anvil cell (DAC) were disclosed via the analysis of Raman spectroscopy. Compared to the shearing force that destroys the crystal structure of trans-azobenzene, the hydrostatic pressure makes the crystal structure of trans-azobenzene stacking more closely and orderly, which are proved by the blue-shifts of Raman bands. During the compression process, the peaks at 1159, 1182 and 1593 cm(-1), highly related to C-H in-plane bending, C-C stretching and in-plane bending vibrations of benzene ring, show more obvious blue-shifts Delta = 21, 35 and 21 cm(-1), respectively. Two types of trans-azobenzene under hydrostatic pressure display different spectral behaviors, due to the strong intermolecular interactions in their crystal forms, but not in powder. When the pressure was gradually reduced to the ambient pressure, the initial forms of the Raman spectra of trans-azobenzene were entirely recovered, indicating that the pressure-induced structural changes are reversible in a certain pressure range. Our spectroscopic observations enable a deeper understanding of the molecular interactions of azobenzene compounds. (C) 2020 Elsevier B.V. All rights reserved.

This study investigates the influence of sintering conditions on electrical properties and positive temperature coefficient of resistance (PTCR) of [Formula: see text] (BTNO) ceramics, fired at [Formula: see text]C for different times from 1 to 6 h in a reducing atmosphere and reoxidised within the temperature range of [Formula: see text]–[Formula: see text]C for 1 h. The results showed that the room-temperature (RT) resistance and the resistance jump of the multilayer BTNO ceramics decreased with an increase in the firing time. Furthermore, the RT resistance of the BTNO samples gradually increased at first and then rapidly increased with increasing reoxidation temperature. In addition, the influence of sintering times on the microstructure of ceramics was also investigated.

The effects of the high pressure on two single crystals, pyrene and N,N-diphenyl-4-(pyren-1-yl)aniline (TPA-Py), were studied by in situ fluorescent and Raman spectroscopies. During the compression, the pyrene with one structureless excimer emission band showed a continuous bathochromic-shift. In contrast, with the pressure increasing to 10.36 GPa, TPA-Py previously dominated with the hybridized local and charge transfer (HLCT) excited state gradually exhibited a new band at longer wavelengths, which is assigned to a new excited state species with the intramolecular charge transfer (ICT) state, caused by the pressure-induced changes on its molecular configuration. Accompanied by the spectral changes, a sequential color variation from blue to cyan was observed, giving a change to yellow and then red. The significant broadening of the full-width half-maximum (FWHM) of the TPA-Py is observed due to the enhanced dipole-dipole interaction and the existence of pressure gradient. Both pyrene and TPA-Py showed the delayed recovery of the luminescence in the compression-decompression cycle, which results from the poor reversibility of electronic structure caused by the compression-induced piezochromic effect. Furthermore, the evolutions of the Raman spectra of pyrene and TPA-Py indicated that the pressure-induced reversible transformation is caused by the molecular conformational change. This study is a deeper understanding of the structure-property relation of the HLCT species and will be a helpful reference for the regulation of photoluminescence in these intramolecular electron donor-acceptor crystal materials.

Quantitative assessment of the intracellular oxidative stress level is a very important problem since it is the basis for elucidation of the fundamental causes of metabolic changes in diseased human cells, particularly cancer. However, the problem proves to be very challenging to solve in vivo because of the complex nature of the problem. Here a computational method is presented for predicting the quantitative level of the intracellular oxidative stress in cancer tissue cells. The basic premise of the predictor is that the genomic mutation level is strongly associated with the intracellular oxidative stress level. Based on this, a statistical analysis is conducted to identify a set of enzyme-encoding genes, whose combined expression levels can well explain the mutation rates in individual cancer tissues in the TCGA database. We have assessed the validity of the predictor by assessing it against genes that are known to have anti-oxidative functions for specific types of oxidative stressors. Then the applications of the predictor are conducted to illustrate its utility.

Bladder cancer (BLCA) is the fourth common cancer among males in the United States, which is also the fourth leading cause of cancer-related death in old males. BLCA has a high recurrence rate, with over 50% of patients which has at least one recurrence within five years. Due to the complexity of the molecular mechanisms and heterogeneous cancer feature, BLCA clinicians find it hard to make an efficient management decision as they lack reliable assessment of mortality risk. Meanwhile, there is currently no screening suitable prognostic signature or method recommended for early detection, which is significantly important to early-stage detection and prognosis. In this study, a novel model, named the risk-weighted sparse regression (RWSR) model, is constructed to identify a robust signature for patients of early-stage BLCA. The 17-gene signature is generated and then validated as an independent prognostic factor in BLCA cohorts from GSE13507 and TCGA_BLCA datasets. Meanwhile, a risk score model is developed and validated among the 17-gene signature. The risk score is also considered an independent factor for prognosis prediction, which is confirmed through prognosis analysis. The Kaplan-Meier with the log-rank test is used to assess survival difference. Furthermore, the predictive capacity of the signature is proved through stratification analysis. Finally, an effective patient classification is completed by a combination of the 17-gene signature and stage information, which is for better survival prediction and treatment decisions. Besides, 11 genes in the signature, such as coiled-coil domain containing 73 (CCDC73) and protein kinase, DNA-activated, and catalytic subunit (PRKDC), are proved to be prognosis marker genes or strongly associated with prognosis and progress of other types of cancer in published literature already. As a result, this paper would more accurately predict a patient's prognosis and improve surveillance in the clinical setting, which may provide a quantitative and reliable decision-making basis for the treatment plan.

All inorganic perovskite quantum dots (QDs) (CsPbX3, X = Cl, Br, I) have been applied on light-emitting devices (LEDs) in recent years due to their excellent optical and optoelectronic properties. However, blue-light emitting perovskite QD LEDs (PQD-LEDs) exhibit poor performances compared with their green- and red-light emitting counterparts. Herein, we fabricated high performing blue-light emitting PQD-LEDs based on phenethylammonium chloride (PEACl) modified CsPb(Cl/Br)3 QDs. Firstly, the PEA-CsPbCl3 QDs were synthesized by introducing certain amounts of PEACl in the conventional hot-injection synthesis process. The merit of our synthesis lies in the fact that not only the Cl vacancies of CsPbCl3 QDs are efficiently modified by introducing the PEACl precursor, but also the partial long-chain organic ligands (OLA) capping on the surface of CsPbCl3 QDs are simultaneously replaced by shorter PEACl chains. Consequently, the PEA-CsPbCl3 QDs emitting at 410 nm with a PLQY of 62.3% were achieved. Furthermore, to meet the requirement of display applications, we exchanged Cl- with Br- ions at room temperature to precisely control the blue emission in the 460-470 nm spectral region and with a maximum PLQY of 80.2% at 470 nm. Finally, the PQD-LEDs based on PEA-CsPb(Cl/Br)3 perovskite QDs emitting at 462, 465, 468 and 470 nm were fabricated. The PQD-LEDs exhibit a maximal EQE of 2.15% and luminance of 620 cd m-2, which provides the highest value of luminance for the PQD-LEDs in the blue spectral range that satisfies the requirement of practical display applications.

The conversion between normal emission and ESIPT can be successfully achieved under pressure and temperature.

The effects of the sintering time on the electrical properties and the positive temperature coefficient of resistance (PTCR) effect of Ba1.006(Ti1-xNbx)O3 (BTN) ceramics were investigated, which were sintered at 1190 ºC for 0.5-6 hours in a reducing atmosphere and then re-oxidized at 800 ºC for 1 hour. The results indicated that the sintering time affected the electrical properties and the PTCR effect of the multilayer BTN samples, whose room-temperature resistance decreased with an increase of the sintering time at same sintering temperature of 1190 ºC. However, the resistance jump first increased and then reduced as a function of the sintering time. Furthermore, The BTN ceramics exhibited a pronounced PTCR effect, with a resistance jump greater by 3.6 orders of magnitude, along with a low RT resistance of 0.14 Ω at a reoxidated temperature of 800 ºC after sintering at 1190 ºC for 2 h in a reducing atmosphere. In addition, the activation energy of samples obtained at different sintering times had also been investigated.

The influence of the Nb5+-doped content and the doping CaCO3 on the electrical properties and the microdefects of BSTN ceramics by Positron Annihilation Techniques were studied, which were fired at 1350 ºC for 2 hours in air. The PTCR characteristics in the BSTN samples were also investigated. Moreover, the information on microdefects in BSTN ceramics was demonstrated by coincidence Doppler broadening spectrum measurements and positron annihilation lifetime spectra. Meanwhile, the influence of the defects on the electrical properties of the ceramics was also revealed. Furthermore, the critical donor-dopant content was 0.4 mol%, which corresponding room-temperature resistivity and the resistivity jumping ratio was 714.3 Ω·cm and 2.77 × 102, respectively. In addition, the average positrons annihilate lifetime t of the BSTN ceramics was investigated as well.

Perovskite white light-emitting devices (WLEDs) without intercalation layers have not been achieved due to the ion exchange. Although the intercalation layers prevent ion exchange between perovskite nanocrystals (NCs), it also creates a new problem of charge imbalance and the structure becomes more complex. In this study, blue emitting ZnCdS/ZnS NCs with high quantum yield and stability are introduced to work with the yellow emission from CsPb(Br/I)3 perovskite NCs for WLEDs. The WLEDs are constituted of ITO/ZnO/PEI/ZnCdS/ZnS NCs/CsPb(Br/I)3 NCs/TCTA/MoO3/Au. This design avoids ion exchange between different perovskites NCs, and realizes white light emission by simple fabrication. As a result, we achieved the white light coordinates of (0.34, 0.34) and a correlated color temperature of 5153 K.

Electrochemical deposition as a liquid phase epitaxial growth method is widely used to fabricate different kinds of hierarchical structures. As a typical heterostructure, TiO2/PbS is widely utilized in the areas of photovoltaics and photocatalysis. Oriented TiO2 nanorod (NR) arrays can provide direct pathways for the electron transport of photoanode. However, the lattice mismatch between TiO2 NR sides and PbS is very large; PbS nanoparticles (NPs) only formed on the top of TiO2 NRs. To solve this problem, TiO2/CdS core/shell nanocables were firstly prepared electrochemically because the lattice ratio between TiO2 and CdS was 0.916; and then, PbS NPs were successfully deposited over CdS shells (the lattice ratio between CdS and PbS was 0.697) to form TiO2/CdS/PbS hierarchical heterostructures. Experimental results demonstrated that the CdS interlayer could effectively promote the growth of PbS NPs on the surface and improve the fill factor and short current density of the photoanodes.

Lead halide perovskites are important materials for solar cells and light emitting diodes (LEDs), but the toxicity of lead is a matter of concern for these and other commercial applications. Here, we demonstrate a lead-free two-dimensional (2D) Ruddlesden–Popper-type (C18H35NH3)2SnBr4 perovskite with a strong emission from the self-trapped states, whose photoluminescence quantum yields in colloidal suspension and in a film are 88 and 68%, respectively. The insulating character of the organic oleylamine cation prevents electronic band formation between the [SnBr6]4– octahedron layers, which results in the Stokes-shifted orange emission. Electroluminescence of these 2D lead-free perovskite materials was demonstrated in an inverted LED structure with a low turn-on voltage of 2.2 V and a luminance of 350 cd/m2.

Pressure-induced remarkable responsive behaviours can be realized in the D–A–D molecule TPA-Py-CN with a dimeric structure.

The individual WO3 film and a series of Hierarchical structure WO3/TiO2 complex films were fabricated by Radio Frequency (RF) magnetron sputtering. The influence of TiO2 thickness on electrochromic properties of WO3 thin films is investigated. The capability for accommodating H+, the diffusion coefficient (D) value of H+ and the life-time or cycle stability of WO3 films were effectively enhanced by appropriate thickness (60 nm) of TiO2 coated on WO3.

Two polymorphs of 9,10-bis(phenylethynyl)anthracene (OC and RC) were obtained and they were characterized by multi spectroscopies including X-ray diffraction, absorption, fluorescence and Raman. The single-crystal structure analysis shows that RC has richer intermolecular interactions (C–H … π and C–H⋯H–C) than OC, which accounts for different spectroscopic behaviors of RC from OC in high pressure studies. Under mechanical grinding, two polymorphs have similar spectral changes in their fluorescence as significant enhancement and slight blue-shifts of the shoulder emission bands at lower wavelength, except that RC shows more sensitive to grinding than OC. During the compression process applied by diamond anvil cell (DAC), OC and RC both demonstrate remarkable red-shifts with increasing pressure, while RC shows a smaller shifting rate than OC. These spectral phenomena reveal that the richer intermolecular interactions in RC can be easily destroyed upon grinding. This work provides the in-depth insight into the mechanism of mechanochromism and the structure-property relation, and proves again that the intermolecular interactions play the key role in modulating the photo-physical properties.

Advanced Optical MaterialsVolume 6, Issue 3 1870013 Back CoverFree Access Reversible Emission Shift: Pressure-Induced Wide-Range Reversible Emission Shift of Triphenylamine-Substituted Anthracene via Hybridized Local and Charge Transfer (HLCT) Excited State (Advanced Optical Materials 3/2018) Aisen Li, Aisen Li State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, Jilin University, Changchun, 130012 P. R. China College of Physics, Jilin University, Changchun, 130012 P. R. ChinaSearch for more papers by this authorZhiyong Ma, Zhiyong Ma College of Chemical Engineering, Beijing University of Chemical Technology, Beijing, 100029 P. R. ChinaSearch for more papers by this authorJinxia Wu, Jinxia Wu State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, Jilin University, Changchun, 130012 P. R. ChinaSearch for more papers by this authorPing Li, Ping Li State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, Jilin University, Changchun, 130012 P. R. ChinaSearch for more papers by this authorHailong Wang, Hailong Wang State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, Jilin University, Changchun, 130012 P. R. ChinaSearch for more papers by this authorYijia Geng, Yijia Geng State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, Jilin University, Changchun, 130012 P. R. ChinaSearch for more papers by this authorShuping Xu, Shuping Xu State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, Jilin University, Changchun, 130012 P. R. ChinaSearch for more papers by this authorBing Yang, Bing Yang State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012 P. R. ChinaSearch for more papers by this authorHouyu Zhang, Houyu Zhang State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, Jilin University, Changchun, 130012 P. R. ChinaSearch for more papers by this authorHaining Cui, Haining Cui College of Physics, Jilin University, Changchun, 130012 P. R. ChinaSearch for more papers by this authorWeiqing Xu, Weiqing Xu State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, Jilin University, Changchun, 130012 P. R. ChinaSearch for more papers by this author Aisen Li, Aisen Li State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, Jilin University, Changchun, 130012 P. R. China College of Physics, Jilin University, Changchun, 130012 P. R. ChinaSearch for more papers by this authorZhiyong Ma, Zhiyong Ma College of Chemical Engineering, Beijing University of Chemical Technology, Beijing, 100029 P. R. ChinaSearch for more papers by this authorJinxia Wu, Jinxia Wu State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, Jilin University, Changchun, 130012 P. R. ChinaSearch for more papers by this authorPing Li, Ping Li State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, Jilin University, Changchun, 130012 P. R. ChinaSearch for more papers by this authorHailong Wang, Hailong Wang State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, Jilin University, Changchun, 130012 P. R. ChinaSearch for more papers by this authorYijia Geng, Yijia Geng State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, Jilin University, Changchun, 130012 P. R. ChinaSearch for more papers by this authorShuping Xu, Shuping Xu State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, Jilin University, Changchun, 130012 P. R. ChinaSearch for more papers by this authorBing Yang, Bing Yang State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012 P. R. ChinaSearch for more papers by this authorHouyu Zhang, Houyu Zhang State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, Jilin University, Changchun, 130012 P. R. ChinaSearch for more papers by this authorHaining Cui, Haining Cui College of Physics, Jilin University, Changchun, 130012 P. R. ChinaSearch for more papers by this authorWeiqing Xu, Weiqing Xu State Key Laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, Jilin University, Changchun, 130012 P. R. ChinaSearch for more papers by this author First published: 05 February 2018 https://doi.org/10.1002/adom.201870013Citations: 2AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Graphical Abstract The 4-(anthracen-9-yl)-N,N-diphenylaniline (TPA-AN) material displays a wide-range emission shift along with an obvious color change ranging from blue to red under the hydrostatic pressure produced by a diamond anvil cell device. As shown by Weiqing Xu and co-workers in article number 1700647, this mechanochromism is dominated by the separation of hybridized local and charge transfer excited state and the intermolecular interaction between molecules. Citing Literature Volume6, Issue3February 5, 20181870013 RelatedInformation

Inorganic perovskite quantum dots (QDs) have attracted wide attention in display and solid-state lighting because of their easily tunable band-gaps and high photoluminescence quantum yields (PLQY) of green light emission. However, some drawbacks limit their practical applications, including the low PLQY of blue light emission and the instability in the moisture environment. In this work, efficient blue-light emitting CsPbBr3 perovskite QDs with PLQY of 72% were developed through a bandgap engineering approach. The achieved blue-light emitting PLQY is much higher than the values acquired in the inorganic perovskite QDs in the literature. And the emission color of the as-prepared QDs can be facially tuned by only adjusting the reaction temperature. Further, the mono-dispersed perovskite QDs@SiO2 composites were constructed benefiting from the low temperature synthesis. The optical performance of the QDs could be well persisted even in the moisture environment. Finally, the as-prepared QDs@SiO2 composite was fabricated as the QD ink on the anti-counterfeit printing technology, from which the obtained pattern would emit varied color under UV lamp. And the as-prepared composites was also applied for fabricating WLED, with Commission Internationale de l'Eclairage (CIE) color coordinates of (0.33, 0.38) and power efficiency of 32.5 lmW(-1), demonstrating their promising potentials in solid-state lighting.