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A fascinating multifunctional screen window containing air filtration, rain-flow transportation and photochromic functions.

In the recent COVID-19 pandemic, World Health Organization emphasized that early detection is an effective strategy to reduce the spread of SARS-CoV-2 viruses. Several diagnostic methods, such as reverse transcription-polymerase chain reaction (RT-PCR) and lateral flow immunoassay (LFIA), have been applied based on the mechanism of specific recognition and binding of the probes to viruses or viral antigens. Although the remarkable progress, these methods still suffer from inadequate cellular materials or errors in the detection and sampling procedure of nasopharyngeal/oropharyngeal swab collection. Therefore, developing accurate, ultrafast, and visualized detection calls for more advanced materials and technology urgently to fight against the epidemic. In this review, we first summarize the current methodologies for SARS-CoV-2 diagnosis. Then, recent representative examples are introduced based on various output signals (e.g., colorimetric, fluorometric, electronic, acoustic). Finally, we discuss the limitations of the methods and provide our perspectives on priorities for future test development.

The advocacy of smart living results in a high demand for wearable and flexible sensors to monitor human motions. Among these, sensors based on strain–optics conversion are attractive due to their ...

Organic conjugated porous polymers, triazine-Ph-CPP and triazine-Th-CPP, are synthesized and characterized. Without further addition of co-catalysts, triazine-Ph-CPP exhibits a HER of 16 287 μmol g−1 h−1 and an apparent quantum yield of 61.5% at 365 nm, which demonstrates that the dibenzo[b,d]thiophene sulfone and 1,3,5-triazine based polymer is a unique prototype of a highly efficient hydrogen evolution photocatalyst.

Halogen-halogen (X···X) interaction is a kind of strong intermolecular interaction. This interaction has great impact on the aggregation structures and optoelectronic properties of organic π-conjugated molecules. However, it is still a great challenge to tune the X···X interactions among organic π-conjugated molecules. In this article, with trans -stilbene as an example, the regulation of halogen-halogen interactions between organic π-conjugated molecules is achieved through chemical structure modification, that is introducing electron-donating methylthio group and changing the position of halogen substituents on trans -stilbene skeleton. The influence of halogen-halogen interactions on the aggregation structure and luminescence properties of trans -stilbenes was investigated.

It is a very important and challenging topic to design high performance n-channel organic semiconductors with a new type conjugated skeleton. Herein, a new class of n-channel organic semiconductors, pyrrolo[3,2-b]pyrrole-based quinoidal molecules QBPBP and QFBPBP, was designed and synthesized. Both compounds have low-lying lowest unoccupied molecular orbital energy level and high thermal stability. Single crystal structures reveal they adopt unusual two-dimensional layer-type packing structures in single crystals. Multiple π–π and CN···H interactions are observed in the layer, and alkyl–alkyl chain interactions exist between layers. Transistors based on single ribbons displayed gate voltage-dependent electron mobility with an average of 4.0 cm2 V–1 s–1 and a peak over 6.0 cm2 V–1 s–1 under N2. These results demonstrate pyrrolo[3,2-b]pyrrole-based quinoidal molecules are a new prototype for high performance n-channel organic semiconductors.

Due to their strong intermolecular interactions, polymer semiconductors aggregate in solution even at elevated temperature. With the aim to study the effect of this kind preaggregation on the order of thin films and further transistor performance, bi-thieno[3,4-c]pyrrole-4,6-dione and fluorinated oligothiophene copolymerized polymer semiconductor P1, which shows strong temperature-dependent aggregation behavior in solution, is synthesized. Its films are deposited through a temperature-controlled dip-coating technique. X-ray diffraction and atomic force microscopy results reveal that the aggregation behavior of P1 in solution affects the microstructures and order of P1 films. The charge transport properties of P1 films are investigated with bottom-gate top-contacted thin-film transistors. The variation of device performance (from 0.014 to 1.03 cm2 V–1 s–1) demonstrates the importance of optimizing preaggregation degree. The correlation between preaggregation degree and transistor performance of P1 films is explored.

A facile and unusual reaction between thienoquinone compound QDTBDT2C and copper is reported. The formation of Cu-QDTBDT2C complex is proved by absorption spectra, IR spectra, Raman spectra, and X-ray photoelectron spectroscopy data. This complex can serve as a doping layer at the interface of Cu/QDTBDT2C and greatly improve the performance of organic transistors in which the copper electrode is source/drain electrodes and QDTBDT2C is an active layer. The transistors display an electron mobility of 0.95 cm

Bi-thieno[3,4]pyrrole-4,6-dione (bi-TPD) based copolymers containing 1,2-bis(2-thienyl)ethene (P1) and 1,2-diphenylethene (P2) units are synthesized and characterized. Their physicochemical and electrical properties as well as molecular packing structures in thin films have been fully investigated. P1 has higher HOMO energy levels and smaller bandgap than P2, which is attributed to the stronger electron-donating ability of 1,2-bis(2-thienyl)ethene unit. Both polymers form continuous films and adopt face-on and edge-on co-orientation in the aggregation states. The crystallinity of P1 film is higher than that of P2 film. The optimal field-effect mobility is 0.74 cm2V−1s−1 for P1 films and 0.32 cm2V−1s−1 for P2 films. These results demonstrated the merits of 1, 2-bis(2-thienyl)ethene unit and the potential applications of bi-TPD based polymers in high performance polymer transistors.

Bithienopyrroledione (bi-TPD) based polymers P1 and P2 are designed and synthesized. Photovoltaic devices based on P1:PC71BM and P2:PC71BM blend films show power conversion efficiencies (PCEs) of 8.22% and 9.08%, respectively, whereas devices based on their thienopyrroledione (TPD)-based analogue P3 and PC71BM blend films display a PCE of 5.10%.

The novel dicyanomethylene-substituted 1,2-bis(thieno[3,2-b]thiophene-2-yl)ethene based quinoidal compounds QBTTE and F2-QBTTE are reported. The F⋯H (vinylene) hydrogen bonds lock the backbone conformation and greatly improve the transistor performance of F2-QBTTE.

The furan-thiophene-based quinoidal organic semiconductor, TFT-CN, is designed and synthesized. TFT-CN displays a high electron mobility of 7.7 cm(2) V(-1) s(-1) , two orders of magnitude higher than the corresponding thiophene-based derivative.

Bi-thieno[3,4-c]pyrrole-4,6-dione (bi-TPD) and oligothiophene copolymer semiconductors P1–P4, with different alkyl side chain densities and orientations, were synthesized. Their physicochemical properties were systematically characterized. With trimethoxy(octadecyl)silane (OTMS) modified SiO2 as substrates, the as-spun thin films of P1, P3 and P4 adopted the face-on packing structure while the P2 films displayed the edge-on packing arrangement. The packing differences of P1–P4 were ascribed to their different alkyl chain densities and orientations. The higher alkyl chain density is favorable to the face-on packing structure. After thermal annealing, the packing orientation of P2 remained and the packing structures of P1, P3 and P4 changed. P1 and P4 based films exhibited the coexistence of the edge-on and face-on packing structures in which the edge-on structure was predominant, and P3 based thin films were converted to the edge-on packing arrangement. The relationship between the aggregation structures and charge carrier transport properties of these films was explored through thin film transistors. All devices exhibited p-channel behavior with a maximum mobility larger than 1.0 cm2 V−1 s−1. Interestingly, the P3 films with face-on packing structures displayed a high mobility up to 1.18 cm2 V−1 s−1 (average mobility of 1.02 cm2 V−1 s−1), very close to the edge-on packed films which showed a maximum mobility of 1.4 cm2 V−1 s−1 (average mobility of 1.16 cm2 V−1 s−1). These results demonstrated, similar to edge-on packing structures, the face-on packing arrangement with π–π interactions facilitated charge carrier transport.

Organic field-effect transistors have found wide applications in flexible displays, smart cards, sensors and so on because they can be fabricated on flexible substrates with large scale and low cost. Though great progress has been made on p-channel organic field effect transistors, the development of n-channel organic field-effect transistors is largely lagged behind their p-channel counterparts. The lack of high performance n-channel organic semiconductors has become one of the bottlenecks for organic field-effect transistors. Low LUMO energy level is one of the characteristics of n- type organic semiconductors. The low LUMO level of organic semiconductors can not only reduce the electron injection barrier, in favor of electrons transferring from the electrode into the semiconductor layer, but also prevent the electron charge carriers being trapped by air and water and obtain ambient stability. Thiophene quinoidal organic semiconductors have attracted great attentions recently because they have low-lying LUMO energy levels and strong intermolecular interactions, and usually display high electron mobility. This review summarizes the application of the thiophene quinoidal organic semiconductors in organic transistors in recent years. According to the characteristic of the molecular structures, in the review, the thiophene quinoidal organic semiconductors are divided into two classes: the oligo- thiophene quinoidal organic semiconductors and fused-ring thiophene quinoidal organic semiconductors. Compared to the extensive studied aromatic diimide n-type organic semiconductors, the research on thiophene quinoidal organic semiconductors is not sufficient and the molecular species of thiophene quinoidal compounds is not rich. However, the excellent electron transport properties of thiophene quinoidal organic semiconductors support their potential applications as high performance solution processable n-channel organic semiconductors. In addition to the application in organic transistors, thiophene quinoidal compounds usually have reversible redox property, high electron affinity and other characteristics, and will have potential applications in organic solar cells, charge transfer salts, organic memories and sensors. We believe that the research of thiophene quinoidal organic semiconductors will make more progress.

Acceptor-donor-acceptor type compounds W1–W3 were designed and synthesized. These compounds had the same donor moiety of 2,6-di(thiophen-2-yl)dithieno[3,2-b:2′,3′-d]thiophene and different acceptor groups of 2-dicyanomethylen-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran (TCF), dicyanovinyl (DCV) and 3-ethyl-2-thioxothiazolidin-4-one. Experimental results showed all compounds had high thermal stability and strong absorption in the visible light region. Among them, compound W1 with TCF as acceptor group displayed the lowest LUMO energy level of −3.74 eV and the smallest HOMO-LUMO band gap of 1.74 eV, suggesting the potential applications of TCF unit in low band gap organic semiconductors.

pi-conjugated oligomers 1a-b and 2a-b, containing furan-fused and thiophene-fused aromatic units, were systematically designed and successfully synthesized. Their physicochemical properties were thoroughly investigated. Experimental results showed that different furan/thiophene ratios and fused-aromatic skeletons strongly affected the HOMO energy levels, fluorescent quantum yields and aggregation behaviors of the oligomers. Single crystal structures revealed compound 1b adopted typical herringbone structure with strong C-H center dot center dot center dot pi, S center dot center dot center dot pi and S center dot center dot center dot S interactions in the crystals. 2a formed slipped pi-pi stacking in the crystals, and strong pi center dot center dot center dot pi and O center dot center dot center dot O interactions were observed. (C) 2014 Elsevier Ltd. All rights reserved.

Two novel polymers PDPP3T-CN and PDPPTPT-CN containing nitrile-substituted thienyl and phenyl units were designed and synthesized. The influence of nitrile groups on the electronic properties and charge-carrier transport of the polymers was thoroughly investigated and highlighted by comparing with the corresponding non-nitrile substituted polymers. Experimental results showed that the introduction of nitrile groups lowered the HOMO and LUMO energy levels of polymers by about 0.3 eV and 0.2 eV, respectively. Thin film transistor characteristics displayed that both polymers exhibited electron-dominated ambipolar behavior under ambient conditions. The highest electron/hole mobilities were 0.18/0.0083 cm2 V−1 s−1 for PDPPTPT-CN and 0.09/0.0017 cm2 V−1 s−1 for PDPP3T-CN, one of the highest electron mobilities for DPP-based polymers measured under ambient conditions with bottom-gate/top-contact device configurations.

π-Extended nine-ring-fused linear thienoacenes 1a–c with internal thieno[3,2-b;4,5-b′]dithiophene substructures were synthesized. Their optical and electrochemical properties were investigated. Thin-film transistor characteristics showed all compounds displayed high device reproducibility and nearly no dependence on substrate temperatures. The highest performance was observed for 1c-based devices with mobility up to 1.0 cm2/Vs and current on/off ratio of 10(7), whereas the maximum mobility was 0.5 cm2/Vs for 1b and 0.011 cm2/Vs for 1a.

Three regioisomeric sulfur-bridged pyrene-thienoacenes (PTAs) have been synthesized. The crystal structures and optoelectronic properties of these ring-fused PTAs and their ring-opened precursors have been fully investigated. Among these isomers, the [3,4]-extended compound (4-S-PTA) shows the most pronounced spectral red-shift and highest quantum yield as well as large transistor mobility.

A solution-processable tetrathienoquinoidal semiconductor CMHT was synthesized and characterized. Single crystal diffraction results showed that CMHT adopted slipped π–π stacking in the crystal structure. Multiple intermolecular interactions, such as S⋯N and S⋯C (where C is the carbon on the cyano group), existed among neighboring molecules, which formed a 2-dimensional charge transport network. Solution-processed thin film transistors of CMHT displayed a high electron mobility of up to 0.22 cm2 V−1 s−1 under ambient conditions, one of the highest electron mobilities for quinoidal semiconductors. The correlation between the molecular packing of the CMHT and transistor performance was studied by AFM and XRD.

We herein report on an efficient synthesis of diacenaphthylene-fused benzo[1,2-b:4,5-b′]dithiophenes and demonstrate that their packing structure in the solid state depends on the substituent groups. These compounds form dimers with their radical cations in high concentration solution and exhibit good field-effect mobility.

Thieno[3,4-c]pyrrole-4,6-dione (TPD) containing copolymer semiconductors P1–P3 were strategically designed and successfully synthesized. Their physicochemical properties were thoroughly investigated. All polymers exhibited good solution processability and high humidity stability in thin film transistors (TFTs). Transistor electrical characterization showed the device performance was sensitive to the alkyl chain substituent orientations of the polymers. A maximum TFT hole mobility of ∼1.29 cm2/(V s) was observed for P3-based devices, a recorded mobility for TPD containing polymer semiconductors reported to date. The corresponding thin-film morphologies and polymer chains packing were investigated in detail by AFM and 2D-GIXD to correlate with the alkyl orientation-dependent carrier mobility of P1–P3. Experimental results showed the alkyl chain orientations determined the polymer chains packing pattern in the thin films, the film morphologies, and the resulting device performances of P1–P3.

A series of dicyanomethylene-substituted 2,5-di(thiophen-2-yl)thieno[3,2-b]thieno-quinoids, in which soluble alkyl chains (2-decyltetradecyls) are substituted at different positions (namely, 2,2′-positions (Compound 1); 3,3′- positions (Compound 2); 6,6′-positions (Compound 3)), are strategically designed and successfully synthesized. The photophysical and electrochemical properties as well as molecular packing of these new compounds are thoroughly investigated. Thin film transistor measurements reveal that Compounds 1–3 display markedly different charge transport performance. The solution processed thin film transistors of Compound 2 exhibits the highest electron mobility of up to 0.22 cm2 V−1 s−1 under ambient conditions, one and three orders of magnitude higher than those of Compounds 3 and 1, respectively, demonstrating the strong impact of alkyl chain orientations on transistor performance.

The film morphology, structure, and electrical properties of lead phthalocyanine (PbPc) epitaxially grown on 5,5 ''-bis(3'-fluoro-biphenyl-4-yl)-2,2':5',2 ''-terthiophene (m-F2BP3T) inducing layer substrates were systematic investigated. The morphologies of PbPc films sensitively depend on the thickness of the inducing layer and substrate temperature. All the epitaxial PbPc films with high quality presented the triclinic form with a variation of the out-of-plane orientation. The field-effect mobility of the epitaxial PbPc films was 0.05-0.31 cm(2)/V s, which was significantly improved by 1-2 orders of magnitude compared to the traditional films. The evolution of the device performance is the synergistic effect of the morphology and out-of-plane orientation of the triclinic form of PbPc. The higher quality of the films and the smaller ratio of (100)/(001), the higher device performance is. A clear relationship between the morphology, structure, and the performance of epitaxial PbPc-based organic field-effect transistors was reported. (C) 2012 Elsevier B.V. All rights reserved.

Efficient planar organic solar cells extending the response into the near-infrared (NIR) were fabricated using the highly ordered Titanyl phthalocyanines (TiOPc) films as the donor layer. This type of films obtained through the weak epitaxy growth (WEG) method presents good continuity and integrity with the low density of grain boundaries. More importantly the films own a strong absorption in the NIR (750-950 nm) and a broad absorption spectrum from 550 to 950 nm. Meanwhile the high external quantum efficiency (EQE) is obtained in the NIR with the peak value over 38% and the EQE is over 18% in the entire response range, which could benefit from the long exciton diffusion length and the high carrier mobility of the highly ordered films. Thereby the fabricated planar solar cells achieve a high short-circuit current density (J(sc)) of 9.26 mA cm(-2) and a power conversion efficiency (PCE) of 2.67%. (C) 2012 Elsevier B.V. All rights reserved.

Weak epitaxy growth (WEG) is an effective method in the preparation of high-mobility thin films of disk-like organic semiconductors. The growth behavior and quality of the epitaxial thin film are closely related to the inducing layers. Here, a series of fluorinated molecules, 5,5"-bis(3'-fluoro-biphenyl-4-yl)-2,2':5',2"-terthiophene (m-F2BP3T), 5,5"-bis(3',5'-difluoro-biphenyl-4-yl)-2,2':5',2"-terthiophene (F4BP3T), and 5,5"-bis(4'-fluoro-biphenyl-4-yl)-2,2':5',2"-terthiophene (p-F2BP3T) as well as a referenced molecule 5,5"-bis(biphenyl-4-yl)-2,2':5',2"-terthiophene (BP3T), are introduced to serve as inducing layers for the epitaxy growth of phthalocyanine. Compared to the nonfluorinated inducing layer, the interactions between the fluorinated inducing layer and phthalocyanine might be relatively strong due to the potential existence of C-H···F weak hydrogen bonds. The growth behavior and mechanism of phthalocyanine on the fluorinated inducing layers are investigated by atomic force microscopy (AFM), grazing incidence X-ray diffraction (GIXD), selected area electron diffraction (SAED). According to the AFM and SAED, H(2)Pc presents a selective epitaxy growth depending on the position of fluorine: epitaxy growth on m-F2BP3T and F4BP4T, and nonepitaxy growth on p-F2BP3T. Comparison of CuPc with F(16)CuPc on monolayer p-F2BP3T further revealed that the uncommon nonepitaxy growth behavior of H(2)Pc (CuPc) on p-F2BP3T mainly originates from the enhanced interactions between the two types of molecules. As a consequence, the capability of molecules orienting themselves along the surface channel is decreased; meanwhile, the demand of the upper limit of the lattice mismatch is more rigorous for commensurate epitaxy. Finally, the oriented nucleation of H(2)Pc (CuPc) on monolayer p-F2BP3T is affected, and netlike crystals are formed. The sudden change of H(2)Pc (CuPc) from multiorientation on monolayer to just one orientation on double-layer p-F2BP3T suggests that there is a critical lattice mismatch value for commensurate epitaxy in WEG when the molecule-substrate interactions are enhanced.

A donor–acceptor–donor (D–A–D) type small molecule DHB-QDTB, with dicyano-substituted quinoidal benzo[1,2-b:4,5-b′]dithiophene as the acceptor, was designed and synthesized. A high electron mobility up to 0.88 cm2 V−1 s−1 was observed for DHB-QDTB based transistors under ambient conditions, suggesting quinoidal benzo[1,2-b:4,5-b′]dithiophene is an excellent acceptor unit in D–A type n-channel organic semiconductors.

The growth process and phase state of 5,5''-bis(3'-fluoro-biphenyl-4-yl)-2,2' : 5',2''- terthiophene (m-F2BP3T) thin films were investigated by atomic force microscopy (AFM), in-plane and out-of-plane X-ray diffraction (XRD), and selected area electron diffraction (SAED). Two meso-phases (thin film phases) of m-F2BP3T films on SiO(2) surface were obtained in the early stages. The m-F2BP3T films initially exhibited two-dimensional (2D) layers (≤4 ML) followed by three-dimensional (3D) island growth. The film structure evolved two thin film phases in the first four layers and the bulk phase was formed from the fifth layer, which occurred concomitantly with the change of the growth mode. Moreover, the variation of weak epitaxy growth behavior of ZnPc from 2D to 3D growth further reflects that the phase state of the first three layers is different from that of the fourth layer, in spite of ZnPc crystals showing just one orientation corresponding to commensurate epitaxy. The novel phase behavior is closely related to the synergistic effects of the outstanding soft matter properties, limited elasticity of organic molecules, and strain originating from the SiO(2) substrate. This study investigates novel phase behavior in organic thin films and provides significant insight into the mechanism of the phase transition.

High-quality mixed crystals with mixing-ratio-dependent lattice parameters and electronic structure are obtained by co-deposition of two organic molecules. Using the mixed films as the inducing layer in weak epitaxy growth, the mobility of VOPc transistors is finely tuned. This is possible because of the cooperative effect between the tunable lattice parameters and electronic structure.

A novel solution-processable dicyano-substituted quinoidal oligothiophene molecule CDT-2T(CN)4 was synthesized and characterized. CDT-2T(CN)4 displayed high thermal stability and broad thin film absorption in the near IR region. Electrochemical results showed that CDT-2T(CN)4 exhibited reversible oxidation and reduction peaks with the LUMO energy level at −4.2 eV and the HOMO energy level at −5.3 eV. The solution processed thin film transistors of CDT-2T(CN)4 displayed electron-dominant ambipolar transport behavior under ambient conditions. The optimal saturation hole and electron mobilities were 0.003 and 0.023 cm2 V−1 s−1, respectively, one of the highest values for solution processed quinoidal based ambipolar organic semiconductors with good ambient stability.

Efficient parallel tandem organic solar cells are demonstrated by using the highly crystalline chloroaluminum phthalocyanine (AlClPc) films as the planar layer. Their broad photoresponse from 400–900 nm is contributed to the strong near-infrared absorption of the AlClPc films and the good complementarity between AlClPc and zinc phthalocyanine. Importantly, the high external quantum efficiency is obtained in the entire response range with the peak value 65% due to the high carrier mobility of the AlClPc films, and correspondingly the high power conversion efficiency of 3.5% is attributed to the large short circuit current density of 12.15 mA/cm2.