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The performance of perovskite solar cells (PSCs) is often constrained by significant open‐circuit voltage (VOC) losses attributed to non‐radiative recombination processes induced by detrimental trap states. Surface treatments using passivating ligands typically involve single active binding sites on perovskite, posing challenges for effective passivation. Here, an aromatic donor‐acceptor (D‐A) configured phthalocyanine treatment is proposed to aim at dual‐site passivation of uncoordinated lead ions and effective mitigation of shallow and deep‐level defects on the perovskite surface. The resulting benign p‐type surface facilitates a more favorable energy level alignment and reduces energetic mismatches at the perovskite/Spiro‐OMeTAD interface. Pc‐BTBC, with its aromatic D‐A configuration, demonstrated compatibility with various perovskite compositions. Optimized PSCs achieves a power conversion efficiency (PCE) of 25.15% and reduces the VOC deficit to 0.379 V. Furthermore, encapsulated devices exhibited enhanced stability under damp‐heat conditions (ISOS‐D‐2, 50% RH, 65°C) with a T92 of 1000 h and maintained maximum power point tracking under continuous light in ambient air at 65°C (ISOS‐L‐2). Notably, fabricated wide‐bandgap semitransparent PSCs (ST‐PSCs) achieved a PCE of 20.29%, while four‐terminal perovskite/silicon tandem solar cells (4T‐P/STSCs) demonstrated an efficiency of 29.38%. This study provides insights into minimizing VOC losses and represents significant progress toward commercializing perovskite photovoltaics. [ABSTRACT FROM AUTHOR]

A kind of D-π-A mechanoresponsive luminescent molecule 2- (4- (1H-phenanthro[9,10-d] imidazol) benzylidene) malononitrile (ANPPI) was synthesized and characterized by UV absorption, photoluminescence, and other techniques. The obvious mechanoresponsive properties of ANPPI were reversible upon grinding and fuming, and were demonstrated by X-ray diffraction, scanning electron microscopy, and differential scanning calorimetry. [ABSTRACT FROM AUTHOR]

In this study, the computational studies of the PO3H2, CONHOH, and SO2H (A1–A3) molecules were investigated for optoelectronic applications on the basis of tetrahydroquinoline (C1-1) dye. Besides, a detailed calculation of the molecular structures, energy levels, driving force of injection, regeneration, non-linear optical (NLO) property, chemical hardness, excitation binding energy, light-harvesting efficiency (LHE), absorption spectra, and photovoltaic (PV) parameters were all discussed in details using density functional theory (DFT) and time-dependent DFT (TD-DFT) methods. The optoelectronic properties of C1-1-based A1–A3 molecules are originated to be tuned by changing the position of the acceptor. To get a maximum absorption spectrum of C1-1, Becke's three-parameter and Lee–Yang–Parr (B3LYP), Coulomb-attenuating method-B3LYP (CAM-B3LYP), and Head-Gordon model (ωB97XD) were used for the TD-DFT method. Results reveal that the TD-ɷB97XD and 6-31G(d) combined functionals were provided reliable effects to the C1-1. Therefore, absorption spectra of the A1–A3 dyes were followed by the TD-ɷB97XD/6-31G(d) techniques. The designed A1 (PO3H2) dye displayed a smaller energy gap and red-shifted broadened spectra than the other dyes and C1-1 can be utilized to get a better PV properties. In addition, NLO properties of the A1–A3 chromophores were calculated by the polarizability and first-order hyperpolarizability. Consequently, A1 dye has a superior value of the NLO activity. This study will deliver a valuable reference to the upcoming molecular proposal of tetrahydroquinoline dyes for optoelectronic applications. [ABSTRACT FROM AUTHOR]

A series of D-π-A type conjugated microporous polymers (CMPs) are constructed with the PDI as strong electron donors (D), biphenyl as "π-bridge" (π), and BTDO as strong electron acceptors (A) units, and the polymers show characteristics of adjusted geometrical and energy adaptability of polymeric structure for the highly improved photocatalytic hydrogen evolution rate (HER) (48.54 mmol/h g−1) under visible light condition. [Display omitted] • A series of D-π-A type CMPs based on the perylene diimide (PDI) are constructed. • The PDI was firstly introduced in the CMPs as ideal structure and energy regulator. • The CMPs show highly improved HER activity (48.54 mmol/h g−1) in visible light. • The coplanarity of the CMPs is promoted as the added biphenyl acted as π-bridges. • The structural and energy adaptability of the CMPs is associated on HER activity. Efficient photocatalysts rely on constructing heterostructure with reasonable configuration. In this study, a novel conjugated polymer with a D-π-A structure was fabricated from polycondensation of perylene diimide and dibenzothiophene sulfone through the suzuki coupling reaction, during which the biphenyl was incorporated as a π-bridge. The photocatalytic hydrogen evolution performance of these copolymers were optimized by introducing different mass fractions of π-bridges via adjusting the additions of biphenyls The optimized PyBpDBSO-5 copolymer, with 17 wt.% perylene diimide and 5 wt% biphenyl, obtained photocatalytic hydrogen productivity of 48.54mmol/h g−1 under visible light without adding Pt as cocatalyst, which is 146.1 % improvement compared to the poly(dibenzothiophene-S,S-dioxide) (PDBTSO, 19.72mmol/h g−1). Based on the analysis of physical and chemical properties, electrochemical testing, the significant advantages of D-π-A configuration in promoting light absorption, photogenerated carriers transfer and separation was confirmed, which was further rationalized by the larger co-planarity of the polymer based on DFT calculations. This study provides inspiration about construction of conjugated organic polymer catalyst towards efficient photocatalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] Five new dyes with D–π–A structure bearing 5-(methylene)-rhodanine-3-acetic acid as an acceptor-anchoring part and thieno[3,2- b ]indole or benzo[ g ]thieno[3,2- b ]indole as an electron-donating part were synthesized and applied as photosensitizers for dye-sensitized solar cells (DSSCs). In addition, thermal stability, optical and electrochemical properties of these dyes were investigated. The highest PCE value of 1.09% (J sc = 3.01 mA cm–2, V oc = 0.53 V, FF = 0.69) was achieved for DSSC based on benzo[ g ]thieno[3,2- b ]indole dye under AM 1.5G irradiation. [ABSTRACT FROM AUTHOR]

The efficient development of latent fingerprint (LFP) is attractively important for criminal investigation. The low-cost and high-contrast developer is still a challenge. In this study, we designed and synthesized dicyanomethylene-4H-pyran (DCM) derivatives PZ-DCM and Boc-PZ-DCM by introducing of large steric hindrance group Boc, the solid-state fluorescence of DCM derivatives was greatly enhanced. The low-cost fluorescent LFP developers were prepared by blending with different proportion of montmorillonite (MMT). As a result, clear and high contrast fingerprint patterns were obtained with dusting method by the developer with 3% content of Boc-PZ-DCM. Furthermore, we employed the developer with 3% content of Boc-PZ-DCM to develop the sweat latent fingerprints on different substrates by powder dusting, and collected clear fingerprint patterns, indicating that the developer is universal. In a word, the Boc-PZ-DCM/MMT powder is a promising candidate for LFP developer.

Introduction: Photothermal therapy (PTT) was considered as one of the most promising cancer therapies to overcome the severe side effects caused by chemotherapy. Objective: To develope four thiophene analogs to construct novel organic photothermal agents (PTAs) for many biomedical applications in cancer biosensing and photothermal therapies. Methods: The efficacy of four compounds was demonstrated by studies of photothermal properties as well as photothermal therapeutic effects. Results: Tumor ablation experiments indicated that HTN2 can effectively suppress tumors in vivo and in vitro as a novel PTA. Conclusion: PTAs that we designed and synthesized with their advantage of good biocompatibility and facile structural design could be candidates for PTT.

Based on (E)-2-cyano-3-(5-(2-(4-(dimethylamino)phenyl)ethynyl)thiophene-2-yl)acrylic acid (CSD-01) dye, newly designed isolated organic (CSDS1-CBDS7) molecules were investigated for dye-sensitised solar cells (DSSCs) application using the density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations. The electronic and optimised geometry of the CSDS1–CSDS7 derivatives were contained in the electron-donor (D), π-linker (π) and electron–acceptor (A) groups to form a D–π–A structure. Different hybrid functionals were used to get a maximum value of optical absorption UV-Vis peak in CSD-01 dye. Accordingly, a ωB97XD was sensibly found by calculating the UV-Vis in CSD-01. Further, UV-Vis spectra were used to design newly efficient sensitisers by the TD-DFT-ωB97XD-6-31G(d) theory. The CSDS1–CSDS7 dyes were implemented on the driving force of the electron injection ( Δ G inject ), dye regeneration ( Δ G reg ), dipole moment ( μ normal ), light-harvesting efficiency, theoretical open-circuit photovoltage ( e V OC ), excited-state lifetime (τ), the density of state, the exciton binding energy ( E b ) and molecular electrostatic potential. The highest occupied molecular orbitals below the redox electrolyte and lowest unoccupied molecular orbitals above the conduction band edge of the TiO2 surface were successfully identified. Finally, the newly CSDS5 and CSDS6 structured sensitisers were offered theoretical tools for highly efficient organic photosensitisers for further research. [ABSTRACT FROM AUTHOR]

A series of D-π-A type large cyclic polymeric skeletons conjugated microporous polymers (CMPs) are constructed with the TPA as strong electron donors (D), thiophene as "π-bridge" (T), and BTDO as strong electron acceptors (A) units, and the polymers show characteristics of adjusted geometrical and energy adaptability of polymeric structure for the highly improved photocatalytic hydrogen production (PHP) activity (65.41 mmol h−1 g−1) under visible light condition. [Display omitted] • A series of D-π-A type large cyclic polymeric skeletons CMPs are constructed. • The CMPs show highly improved PHP activity (65.41 mmol h−1 g−1) in visible light. • The "bimodal distribution" phenomenon of PHP activity appears twice for the CMPs. • The coplanarity of polymer backbone of CMPs is promoted by structure adjusting. • The geometrical and energy adaptability of the CMPs is associated on PHP activity. Conjugated microporous polymers (CMPs) with a donor–acceptor (D-A) molecular structure usually express the properties of well light-induced electron/hole separation efficacy and high photocatalytic activity. The triphenylamine (TPA) with a special three-dimensional propeller structure was chose as the electron donor, and the dibenzothiophene sulfone (BTDO) groups as the chain scaffold and electron acceptor to construct and prepare a unique "macrocyclic structure" D-A type CMPs photocatalyst (TPA-BTDO) for photocatalytic hydrogen production (PHP). In order to further improve the conjugation degree of the CMPs and enhance the electron transfer capacity and light absorption, the thiophene units was introduced as "π-bridge" to form a macrocyclic D-π-A type CMPs photocatalyst (TPA-T-BTDO). The results show that the addition of thiophene greatly improves the coplanarity between the donor–acceptor units, and the prepared TPA-T-BTDO-1 exhibited an amazing PHP efficiency of 65.41 mmol h−1 g−1 in the visible light region. More importantly, the PHP efficiency also reaches up to 39.63 mmol h−1 g−1 under the natural light conditions. Both the characterizations and DFT simulation results prove that the twisted structure of the TPA donor decreases the dihedral angle between the benzene rings of BTDO and TPA, which improves the coplanarity of polymer skeleton and then prevents the charges transfer along the polymer chain for recombination. This study highlights the significant influence of the geometry of the electron donor on the photocatalytic activity, as well as the strategy of the structure adjusting by adding suitable bridges between the donor–acceptor units. [ABSTRACT FROM AUTHOR]

The donor–acceptor–π-conjugated (D–π–)2A fluorescent dyes OUY-2, OUK-2 and OUJ-2 with two (diphenylamino)carbazole thiophene units as D (electron-donating group)–π (π-conjugated bridge) moiety and a pyridine, pyrazine or triazine ring as electron-withdrawing group (electron-accepting group, A) have been designed and synthesized. The photophysical and electrochemical properties of the three dyes were investigated by photoabsorption and fluorescence spectroscopy, Lippert–Mataga plots, cyclic voltammetry and density functional theory calculations. The photoabsorption maximum (λmax,abs) and the fluorescence maximum (λmax,fl) for the intramolecular charge-transfer characteristic band of the (D–π–)2A fluorescent dyes show bathochromic shifts in the order of OUY-2 < OUK-2 < OUJ-2. Moreover, the photoabsorption bands of the (D–π–)2A fluorescent dyes are nearly independent of solvent polarity, while the fluorescence bands showed bathochromic shifts with increasing solvent polarity (i.e., positive fluorescence solvatochromism). The Lippert–Mataga plots for OUY-2, OUK-2 and OUJ-2 indicate that the Δμ (= μe − μg) value, which is the difference in the dipole moment of the dye between the excited (μe) and the ground (μg) states, increases in the order of OUY-2 < OUK-2 < OUJ-2. Therefore, the fact explains our findings that OUJ-2 shows large bathochromic shifts of the fluorescence maxima in polar solvents, as well as the Stokes shift values of OUJ-2 in polar solvents are much larger than those in nonpolar solvents. The cyclic voltammetry of OUY-2, OUK-2 and OUJ-2 demonstrated that there is little difference in the HOMO energy level among the three dyes, but the LUMO energy levels decrease in the order of OUY-2 > OUK-2 > OUJ-2. Consequently, this work reveals that for the (D–π–)2A fluorescent dyes OUY-2, OUK-2 and OUJ-2 the bathochromic shifts of λmax,abs and λmax,fl and the lowering of the LUMO energy level are dependent on the electron-withdrawing ability of the azine ring, which increases in the order of OUY-2 < OUK-2 < OUJ-2.

Based on 1-phenylpyrrolidine (PT) dye, six new metal-free organic molecules S1–S6, containing PT as donor (D) connected through different linkages (π) and cyanoacrylic acid as acceptor (A), were designed and studied for dye sensitised solar cells (DSSCs). In this paper, D-π-A system of S1–S6 dye molecules was investigated by quantum chemical calculations to inspect the optical absorption properties and photovoltaic (PV) parameters. In particular, there are applied three long-range corrected (LC) functionals, such as B3PW91, CAM-B3LYP and ωB97XD with the time-dependent DFT (TD-DFT) calculation to systematically investigate the absorption peak in PT dye. From the calculated results, CAM-B3LYP functional was a good match with the PT dye. Therefore, the S1–S6 molecules' optical absorption spectra have been computed by using the CAM-B3LYP/6-31+G(d) theory. The conductor-like polarisable continuum model (C-PCM) results show that the precise absorption spectra have attained solvent effect included in the excited state geometries. The frontier molecular orbitals (FMOs) of the HOMOs and LUMOs energies of S1–S6 derivatives confirm positive results on the dye regeneration and electron injection processes. The outcomes display that the benzo[c][1,2,5]thiadizole (S4) and benzo[c][1,2,5]oxadizole (S5) molecules are the most suitable spacers for D to A, owing to longer absorption peaks and revealing red-shifted optical absorption. [ABSTRACT FROM AUTHOR]

A charge transfer dye with the D– π –A structure was synthesized by Pd catalyzed Hartwig–Buchwald coupling and Knoevenagel condensation reaction, using N, N-dihexylbenzo[b]thiophen-6-amine as donor and 2-(3-cyano-4, 5, 5-trimethylfuran-2 (5H)-ylidene)malononitrile (TCF) as acceptor. The solvatochromic and pH switch properties of the as-synthesized dye were investigated through UV-vis absorption and fluorescence emission spectra. A positive solvatochromism of the dye in different polar solvents was observed along with a visible color change of the solution. By adding acid/base into the DMSO solution of the dye, the color as well as the absorption and emission spectra of the solution exhibited outstanding characteristics of pH switch. [ABSTRACT FROM AUTHOR]

Preparation of near-infrared (NIR) emissive fluorophore for imaging-guided PDT (photodynamic therapy) has attracted enormous attention. Hence, NIR photosensitizers of two-photon (TP) fluorescent imaging and photodynamic therapy are highly desirable. In this contribution, a novel D-π-A structured NIR photosensitizer (TTRE) is synthesized. TTRE demonstrates near-infrared (NIR) emission, good biocompatibility, and superior photostability, which can act as TP fluorescent agent for clear visualization of cells and vascular in tissue with deep-tissue penetration. The PDT efficacy of TTRE as photosensitizer is exploited in vitro and in vivo. All these results confirm that TTRE would serve as potential platform for TP fluorescence imaging and imaging-guided photodynamic therapy.

Photothermal therapy (PTT) was considered as one of the most promising cancer therapies to overcome the severe side effects caused by chemotherapy. To develope four thiophene analogs to construct novel organic photothermal agents (PTAs) for many biomedical applications in cancer biosensing and photothermal therapies. The efficacy of four compounds was demonstrated by studies of photothermal properties as well as photothermal therapeutic effects. Tumor ablation experiments indicated that HTN2 can effectively suppress tumors in vivo and in vitro as a novel PTA. PTAs that we designed and synthesized with their advantage of good biocompatibility and facile structural design could be candidates for PTT. [ABSTRACT FROM AUTHOR]

A new series of 4‐hexyl‐4H‐thieno[3,2‐b]indole (HxTI) based organic chromophores is developed by structural engineering of the electron donor (D) group in the D–HxTI–benzothiadiazole‐phenyl‐acceptor platform with different fluorenyl moieties, such as unsubstituted fluorenyl (SGT‐146) and hexyloxy (SGT‐147), decyloxy (SGT‐148) and hexyloxy‐phenyl substituted (SGT‐149) fluorenyl moieties. In comparison to a reference dye SGT‐137 with a biphenyl‐based donor, the effects of the donating ability and bulkiness of the fluorenyl based donor in this D–π–A‐structured platform on molecular properties and photovoltaic performance are investigated to establish the structure–property relationship. The photovoltaic performance of dye‐sensitized solar cells (DSSCs) is improved according to the bulkiness of the donor groups. As a result, the DSSCs based on SGT‐149 show high power conversion efficiencies (PCEs) of 11.7% and 10.0% with a [Co(bpy)3]2+/3+ (bpy = 2,2′‐bipyridine) and an I−/I3− redox electrolyte, respectively. Notably, the co‐sensitization of SGT‐149 with a SGT‐021 porphyrin dye by utilizing a simple "cocktail" method, exhibit state‐of‐the‐art PCEs of 14.2% and 11.6% with a [Co(bpy)3]2+/3+ and an I−/I3− redox electrolyte, respectively. [ABSTRACT FROM AUTHOR]

In this work, new D-π-A dyes bearing thieno[3,2- b ]indole, 7-(tert -butyl)thieno[3,2- b ]indole or benzo[ g ]thieno[3,2- b ]indole as an electron-donating part, 2,2′-bithiophene unit as π-linker and 2-cyanoacrylic acid as an electron acceptor-anchoring part have been readily synthesized and used for dye-sensitized solar cells (DSSCs). In addition, thermal stability, optical and electrochemical properties of these dyes were investigated. The DSSCs based on dyes IS-BTh exhibited values of PCE in the range of 3.43–4.41 % under AM 1.5 G irradiation. The highest PCE value of 4.41 % (J sc = 11.61 mA cm−2, V oc = 0.64 V, FF = 0.59) was achieved for DSSC based on dye IS-BTh-1 , bearing thieno[3,2- b ]indole as an electron-donating part. The temperature dependencies of the photovoltaic parameters for DSSC based on dye IS-BTh-1 were investigated. Three new D-π-A compounds were synthesized and used as photosensitizers for dye-sensitized solar cells (DSSCs), and the highest power conversion efficiency of 4.41 % was achieved for DSSC based on dye IS-BTh-1. [Display omitted] • Novel D-π-A thieno[3,2- b ]indole based photosensitizers were synthesized and used for dye-sensitized solar cells (DSSCs). • The effect at modifying thieno[3,2- b ]indole donor part in the structure of these dyes was investigated. • The highest PCE value of 4.41 % was achieved for DSSC based on dye IS-BTh-1 , bearing thieno[3,2- b ]indole as an electron-donating part. • The temperature dependencies of the photovoltaic parameters for DSSC based on dye IS-BTh-1 were investigated. [ABSTRACT FROM AUTHOR]

Herein, three novel bipolar host materials with D-π-A structure, termed 2CzPm , 3CzPm , and 9CzPm , were successfully synthesized by incorporating a pyrimidine moiety as an accepter and N -phenylcarbazole group as a donor through different connection sites. The three hosts exhibited good thermal stability with a glass transition temperature (T g) of 104, 103, and 102 °C, respectively. They also possessed high enough triplet energy level (E T = 2.58–2.75 eV) to be efficient hosts for red and green phosphorescent organic light-emitting diodes (PhOLEDs) (E T dopants <2.5 eV). Moreover, considerable hole and electron current density in the conventional voltage range were observed, suggesting their good bipolar transport properties. When utilized in green and red PhOLEDs, the devices hosted by 9CzPm exhibited the best electroluminescence (EL) performance with low turn-on voltages (V on) of 2.6 and 2.5 V, and maximum external quantum efficiency (EQE max) of 21.79% and 25.03%, respectively, indicating that pyrimidine moiety is a promising building block for bipolar host materials. [Display omitted] • Three novel bipolar host materials with the D-π-A structure were presented. • Using pyrimidine and pyridine units as an acceptor to facilitate electron transport. • They possess high E T of 2.58–2.75 eV to be efficient hosts for green and red PhOLEDs. • The green device hosted by 9CzPm exhibits the best performance with EQE max of 21.79%. • The red PhOLED based on 9CzPm shows V on of 2.5 V and EQE max of 25.03%, respectively. [ABSTRACT FROM AUTHOR]

A novel symmetrical indolo[3,2- b ]carbazole derivative ( ICZ-CN ) containing dicyanovinyl groups has been designed and synthesized. The typical D-π-A type conjugated compound exhibited an obvious intramolecular charge transfer (ICT) property, which was evidenced by UV-vis absorption, fluorescent emission spectroscopy and density functional theory (DFT) calculations. Meanwhile, ICZ-CN exhibited a strong aggregation-enhanced emission (AEE) characteristic. Interestingly, compound ICZ-CN showed a reversible mechanofluorochromic (MFC) property between yellow and orange-red emission by grinding-fuming processes. The MFC mechanism was investigated through the single crystal structure, the scanning electron microscope (SEM) and the powder X-ray diffraction (XRD). The results showed that the mechanofluorochromic property is attributed to the loose molecular packing by weak intermolecular hydrogen bond interactions was destroyed and generated the phase transformation from crystalline to amorphous states under external stimulations. The results would be of great help in understanding and designing new MFC materials. [ABSTRACT FROM AUTHOR]

Novel D-π-A conjugated dyes of BODIPY-stilbenes constructed through palladium catalyzed cross coupling reaction, are found to be promising red AIE-active building blocks. Three new aggregation-induced emission enhancement (AIEE) chromophores BODIPY-stilbene 1, 2, 3 with stilbene-based donor-π bridge-acceptor BODIPY (D-π-A) structure have been built, which emit red fluorescence in the solid state with a maximum emission wavelength at 657, 626 and 656 nm, respectively. BODIPY-stilbene 1 show weak fluorescence in pure THF (Φ F =0.05). However, the fluorescence intensities in 90% water fraction THF/H 2 O mixtures (λ em = 636 nm) increased obviously, with the quantum yields of up to 0.10. Meanwhile, BODIPY stilbene 1 with terminal carboxylic acid can achieve fast detection for bovine serum albumin (BSA) based on the AIEE. The red fluorescence intensity of BODIPY-stilbene 1 in the test system at 636 nm is increased by 5.7-fold when the concentration of BSA increased from 0 to50 μM. [ABSTRACT FROM AUTHOR]

We screened five π-conjugated bridges and further designed four dyes FSQ101-FSQ104 with screened π-linker B 1 as bridge, four electron-rich units D 1 -D 4 as donors and electron-withdrawing cyanoacrylic acid as acceptor, based on experimentally synthesized dye SM315 for highly efficient dye-sensitized solar cells (DSSCs) using density functional theory (DFT) and time-dependent density functional theory (TDDFT) methods. Our theoretical results reveal that designed dyes FSQ101-FSQ104 have not only remarkably better light harvesting abilities toward the near-infrared (NIR) region with broader light harvesting efficiency (LHE) curves and higher maximum short circuit current densities ( J sc max ), but also obviously narrower band gaps, larger adsorption energies ( E ads ), lower exciton binding energies (EBEs), larger conduction band energy shifts (Δ E CB ) compared to dye SM315. Therefore, the designed dyes FSQ101-FSQ104 might have superior performances and could be promising sensitizer candidates for highly efficient DSSCs. [ABSTRACT FROM AUTHOR]

The design and synthesis of D–π–A structured Zn(II)–porphyrin sensitizers with extended π-conjugation, coded as SGT-012, SGT-016, SGT-052 and SGT-053 , were explored. The key schematic concept for the molecular design and synthesis of porphyrin sensitizers, with the target of modulation of donor groups by embedding an electron donor into the skeleton of two typical D‐π‐A porphyrin models, such as D–porphyrin-A sensitizers ( SGT-012 and SGT-016 ) and D-triple bond-porphyrin-triple bond- BTD -acceptor sensitizers ( SGT-052 and SGT-053 ), was proposed investigate the influence of the donor ability and the bulk of donor groups on the photophysical properties and cell performance of dye-sensitized solar cells (DSSCs). Also, based on the photophysical properties and cell performances, the co-sensitisation strategy was conducted to further enhance the cell performances. SGT-012 and SGT-052 porphyrins, containing a strong donor unit, exhibited similar S-band absorption and a slightly red-shifted Q-band absorption compared to SGT-016 and SGT-053 porphyrins containing a weak bulky donor unit, respectively. To further extend the π-conjugation and absorption to a longer wavelength range, the triple bond at two meso -positions of the porphyrin core and a benzothiadiazole ( BTD ) strong electron acceptor was introduced to yield SGT-052 and SGT-053 , resulting in a red-shift and broad visible region absorption ability. It was indicated that these modifications lead to the formation of a stronger intramolecular charge transfer complex, which is favourable for harvesting sunlight, than those of SGT-012 and SGT-016 porphyrins. To prevent undesirably reduced V oc caused by charge recombination processes and dye aggregation from porphyrin-sensitized solar cells, HC-Al of co-adsorbent was adopted to fabricate SGT-052- and SGT-053 -based solar cells. The DSSCs with SGT-052 and SGT-053 exhibit better light harvesting ability than the DSSCs with SGT-012 and SGT-016 porphyrins, due to the formation of the stronger intramolecular charge transfer complex. Thus, the incident photon-to-current conversion efficiency ( IPCE ) of SGT-052 and SGT-053 -based DSSCs was extremely red-shifted to a wavelength of 800 nm, resulting in higher J sc values of 15.3 and 14.6 mA cm −2 , respectively. The DSSC utilising SGT-052 and HC-A1 exhibited a higher photovoltaic performance ( η eff ∼9.6%) than did other sensitizers. On the basis of SGT-052 -based DSSC, its DSSCs co-sensitized with SGT-012 were prepared to improve the J sc , V oc and power conversion efficiency (10.2%). [ABSTRACT FROM AUTHOR]

Facile probing organic solvents is attracting intense attention due to the growing environmental issues. Herein, for the first time, we report a novel D-π-A structured methanol responsive fluorescence molecule (TTO), synthesized by coupling triphenylamine (electron-donor) and p -toluenesulfonyl (electron-acceptor) via Cu (I) catalytic 1,3-dipolar cycloaddition (click chemistry) forming a triazole bridge. Density functional theory (DFT) calculations and X-ray single crystal structure reveal that TTO has a highly twisted conformation and unique D-π-A structure which render it exceptional optical properties. TTO exhibits strong fluorescence in methanol (QE > 0.67) but weak fluorescence in other organic solvents (QE < 0.1) including various alcohols and can be used as a highly selective fluorescence probe for methanol identification. Notably, TTO is able to excellently probe methanol from its homologue ethanol in water with a detection limit of below 0.7% (volume concentration), which demonstrates the promise potential of TTO for practical applications. [ABSTRACT FROM AUTHOR]

Zn(II)-porphyrin sensitizers, coded as SGT-020 and SGT-021, are designed and synthesized through donor structural engineering. The photovoltaic (PV) performances of SGT sensitizer-based dye-sensitized solar cells (DSSCs) are systematically evaluated in a thorough SM315 as a reference sensitizer. The effect of the donor ability and the donor bulkiness on photovoltaic performances is investigated for establishing the structure-performance relationship in the platform of porphyrin-triple bond-benzothiadiazole-acceptor sensitizers. By introducing a more bulky fluorene unit to the amine group in the SM315, the power conversion efficiency (PCE) is enhanced with the increased short-circuit current ( Jsc) and open-circuit voltage ( Voc), due to the improved light-harvesting ability and the efficient prevention of charge recombination, respectively. As a consequence, a maximum PCE of 12.11% is obtained for SGT-021, whose PCE is much higher than the 11.70% PCE for SM315. To further improve their maximum efficiency, the first parallel tandem DSSCs employing cobalt electrolyte in the top and bottom cells are demonstrated and an extremely high efficiency of 14% is achieved, which is currently the highest reported value for tandem DSSCs. The series tandem DSSCs give a remarkably high Voc value of >1.83 V. From this DSSC tandem configuration, 7.4% applied bias photon-to-current efficiency is achieved for solar water splitting. [ABSTRACT FROM AUTHOR]

Organic materials with solution and solid dual efficient, color-tunable luminescence are potentially useful for sensors and optical devices. Herein, a series of donor-π-acceptor luminophores, named BM s, with different phenyl substituents at the 3-positions of 7-diethylamino-coumarin was developed. All four compounds with slightly twisted structure rendering BM s have bright emission in solution and solid state. BM s not only possess solvatochromic properties in solution but also realize color tuning from cyan (480 nm) to deep red (661 nm) in solid states. Among them, the fluorescence quantum yield of compound BM1 in solid state reached 98.2%, and the fluorescence quantum yield in solution was 77.1%. Time dependent density functional theory calculation and single crystal analysis show that with the increase in the electron-withdrawing ability of 4-phenyl moiety at the 3-position of coumarin, the charge transfer effect was strengthened gradually, and the photoluminescence mechanism changed from intramolecular charge transfer (ICT) to twisted ICT on account of the electron acceptor changed accordingly. Moreover, the cyan phosphor BM1 and the deep-red phosphor BM4 were laminated to fabricate an impressive warm-white light-emitting diode device with a maximum brightness of 52,090 cd/m2 at an operating voltage of 4.0 V. • A series of donor-π-acceptor luminophores, 7-diethylamino-coumarin derivatives, was developed. • The subtle difference in substituents resulted in remarkable color change both in solution and in solid states. • The photoluminescence mechanism of BM1 - BM4 changed from intramolecular charge transfer (ICT) to twisted ICT. • The synthesized compounds BM1 and BM4 were successfully applied to LED devices. [ABSTRACT FROM AUTHOR]

A class of novel carbazole sensitizers was synthesized with carbazole derivatives as the electron donor, 4-phenyl-2-(thiophen-2-yl) thiazole as π-bridge and cyanoacetic acid as the electron acceptor. Their absorption spectra, photovoltaic performance and electrochemical properties were evaluated. These carbazole sensitizers share the same π-bridge and electron acceptor and display the similar absorption spectra. However, the differences in link mode and substituent bring about the absorptivity variation. It is observed that the link mode of π-bridge at the benzene ring instead of N atom of the carbazole unit favors improving the light absorptivity and lowering the charge recombination. Those carbazole sensitizers show the optimal photovoltaic performance with a J sc of 10.01 mA/cm 2 , V oc of 0.66 V, and ff of 0.72, corresponding to an overall conversion efficiency η of 4.72% under standard AM 1.5G irradiation. [ABSTRACT FROM AUTHOR]

Abstract: A new class of metal-free organic dyes (DH-41–DH-44) containing triphenylamine group as an electron donor, cyanoacrylic acid group as an electron acceptor and a π-linker of 2,2′-bithiophene unit with two hexyl groups at different β-substituted positions have been designed and synthesized. Their photovoltaic performances are characterized experimentally and the structure–performance relationship is explored with the aid of theoretical calculation. Although all the DH dyes show the same structural backbone, changing β-substituted positions of hexyl group at 2,2′-bithiophene unit can alter the molecular coplanarity of conjugated skeleton and the intramolecular charge transfer (ICT) that finally affects the UV–Vis absorption and the photovoltaic performances of the DH dyes. By comparison, the dyes with two hexyl groups at nonortho β-positions of 2,2′-bithiophene unit shows less steric hindrance and better molecular coplanarity that is favorable for improving photovoltaic performances. Among them, DH-44 has the best optimized structure for ICT, so it shows broadened and red-shifted absorption with high molar extinction coefficient, and exhibits excellent photovoltaic performances with high power conversion efficiency of 5.86%, which reaches over 95% of the reference dye N719-based cell fabricated and measured under the same conditions. [Copyright &y& Elsevier]

Organic dyes with a D-π-A structure have drawn increasing attention as sensitizers in dye-sensitized solar cells (DSSCs), due to their rich photophysical properties, easy molecular tailoring, and low-cost production. This review mainly focuses on the relationship between dye structure and photovoltaic properties for organic dyes containing cyanoacrylic acid as both an anchor and an acceptor. This review also introduces different donors and π-conjugation units as building blocks for sensitizer synthesis. [ABSTRACT FROM AUTHOR]

A series of novel acrylate monomers bearing stilbene segments with D-π -A structure, 4-methacrylate-4'-nitro stilbene (NS), 4-(6-methacrylate)hexyl-4'-nitro stilbene (HNS) and 4-(6-methacrylate)hexyl-2,3-dimethoxy-4'-nitro stilbene (DMHNS), were synthesized by the Witting reaction and polymerized by free radical polymerization. These stilbene-containing monomers and polymers were fully characterized, and their fluorescent properties in solution and solid state were also investigated. The emission band of monomers and corresponding polymers in solution also showed a remarkable effect with increasing polarity of the solvent. More importantly, the fluorescence emission could be adjusted from green to orange and even red regions by forming donor-π -acceptor (D-π -A) construction. [ABSTRACT FROM AUTHOR]

Donor-π bridge-acceptor (D-π-A) design principle has been widely employed to build functionalized materials with excellent optical properties, whereas its feasibility in electrocatalytic reactions is seldom investigated. We demonstrate the primary study of D-π-A rule in constructing electrocatalysts for oxygen reduction reaction (ORR) purpose by rationally designing three cobalt porphyrins EGZ1–3 with 9H-carbazole, triphenylamine and N,N-diphenyl-[1,1′-biphenyl]-4-amine as the donor substituents, respectively, cobalt porphyrin as the π bridge, and cyanoacrylic acid as the acceptor unit. The electronic properties of the molecules are calculated using the density functional theory and the composite catalysts EGZs/C are characterized by a series of spectroscopic approaches. The electrochemical measurements show that EGZ3/C attains a more positive reduction potential and a greater response current density than EGZ1/C and EGZ2/C, which is possibly due to the optimized electronic structure and the substituent effect. The electron transfer number as well as hydrogen peroxide generation yield values suggest slightly better selectivity of EGZ3/C and EGZ2/C than those of EGZ1/C (i.e., ~ 2.9, ~ 2.9 vs. ~ 2.7 and ~ 54%, ~ 53% vs. ~ 62%, respectively) towards full oxygen reduction. Our result reveals the feasibility of the D-π-A design rule and the importance of molecular electronic state and the substituent feature in constructing ORR electrocatalysts. [Display omitted] • Three donor-π-acceptor cobalt porphyrins are synthesized. • The electronic structure of porphyrins is calculated by density functional theory. • Porphyrin-carbon black composites are studied in oxygen reduction reaction. • The electrocatalyst EGZ3/C attains the best ORR performance. • Both electronic structure and substituents affect the electrocatalytic activity. [ABSTRACT FROM AUTHOR]

Two new D-π-A-structured dyes (SGT-160 and SGT-161) with the extension of π-conjugation in the acceptor unit have been designed and synthesized to modulate LUMO energy levels and to investigate the photophysical and electrochemical properties as well as cell performances. Based on a reference dye of SGT-130 as a platform of donor-π-bridge-BTD-phenyl-acceptor sensitizers, ethynylphenylene (T-Ph) and 2-ethynylthiophene (T-Th) moieties as an auxiliary π-spacer were introduced to replace the traditional phenylene (Ph) moiety for SGT-160 and SGT-161, respectively. It was found that the insertion of an additional ethynyl moiety into the BTD-Ph acceptor unit significantly enhanced the light-harvesting capability by extending the absorption bands and intensifying the molar absorptivity. Moreover, the π-extension in the acceptor part was beneficial for stabilizing the LUMO energy levels. The density functional theory (DFT) calculations and the partial density of states (PDOS) suggest that the variation of acceptor units affects the electronic transition between the major orbitals of the dyes. As a result, dye-sensitized solar cells (DSSCs) based on SGT-160 with a chenodeoxycholic acid (CDCA) co-adsorbent exhibited high power conversion efficiencies (PCEs) of 10.28%, while DSSCs based on SGT-161 and SGT-130 showed moderate PCEs of 8.05% and 10.06%, respectively. [Display omitted] • D-π-A structured organic dyes of SGT-130, SGT-160 and SGT-161 were designed and synthesized. • The effect of auxiliary ethynyl-based acceptor units on the photovoltaic properties was investigated. • The introduction of π-extended acceptors is a rational design strategy to improve light-harvesting capability. • SGT-160-based DSSCs showed a better PCE (10.28%) than other dyes. [ABSTRACT FROM AUTHOR]

• D-π-A TANI derivatives from TANI and substituted benzaldehyde were synthesized. • TANI derivatives substituted by -OH and -NR 2 showed khaki to green color change. • TANI-4DMA-2OH-BA had short switching time and good cycling stability. Tetraaniline (TANI) and the benzene ring modified by different groups (-OH, -NR 2) are connected by the π bond (C=N). A series of TANI derivatives with D-π-A structure are easily synthesized by the Schiff-base reaction and named as TANI-2OH-BA, TANI-4DEA-BA, TANI-4DEA-2OH-BA and TANI-4DMA-2OH-BA, according to the type and location of substituent groups. The introduction of D-π-A structure can not only reduce the redox potential, but also regulate the electrochromic properties of materials by changing the substituent groups. TANI-4DEA-2OH-BA and TANI-4DMA-2OH-BA films show the khaki (reduction state) to green (oxidation state) color change, which are obviously different from that of TANI (colorless to blue). TANI-4DMA-2OH-BA has the shortest switching time (t b /t c =1.6 s/2.6 s) and best cycling stability (charge retention of 93.3% after 500 CV cycles), attributed to the reduction of intermolecular forces and film compactness. Moreover, the TANI-4DMA-2OH-BA/WO 3 electrochromic device presents similar color changes with the TANI-4DMA-2OH-BA film, and also has good cycling stability and short switching time. In short, constructing D-π-A structure is an effective method to design the color of oligoaniline, and TANI-4DMA-2OH-BA will be a promising material in camouflage and other aspects. [ABSTRACT FROM AUTHOR]

Dye-Sensitized Solar Cells: 14.2% Efficiency Dye-Sensitized Solar Cells by Co-sensitizing Novel Thieno[3,2-b]indole-Based Organic Dyes with a Promising Porphyrin Sensitizer (Adv. Keywords: co-sensitization; dye-sensitized solar cells; D- -A structure; organic dyes; structure-performance relationship EN co-sensitization dye-sensitized solar cells D- -A structure organic dyes structure-performance relationship 1 1 1 04/23/20 20200421 NES 200421 In article number 2000124, Hwan Kyu Kim and co-workers develop a series of highly efficient organic dyes and a simple co-sensitization method for dye-sensitized solar cells with state-of-the-art efficiency. Co-sensitization, dye-sensitized solar cells, D- -A structure, organic dyes, structure-performance relationship. [Extracted from the article]

• A novel AIE molecule was facilely synthesized through a single-step reaction with commercially available materials. • The D-π-A structure endows the AIE molecule with TICT characteristic, making it a reversible fluorescent thermometer. • The AIE molecule exhibited good biocompatibility. • The AIE molecule can be used as a probe for lipid droplets-specific imaging and a photosensitizer to kill cancer cells. Luminogens with aggregation-induced emission (AIE) characteristic drew extraordinary attention owing to their excellent luminescence properties in aggregated state or solid state, which showed wide application prospect in chemical sensing, bioimaging, lighting material and display material. In this work, a novel AIE molecule of (2,3-bis(4-(dimethylamino)phenyl)quinoxalin-6-yl)(phenyl)methanone (designated as LD-red) was facilely synthesized through a single-step reaction with commercially available materials. Based on its intrinsic twisted intramolecular charge transfer (TICT) characteristic, LD-red was successfully utilized as a reversible fluorescent thermometer. More importantly, LD-red exhibited good biocompatibility, which not only can be used as a probe for lipid droplets-specific imaging, but also can work as a promising photosensitizer to kill cancer cells through generation of reactive oxygen species (ROS) upon white light irradiation. LD-red enriches the kinds of AIEgens and, more importantly, this work provides a new strategy for constructing multifunctional AIEgen with TICT characteristic. [ABSTRACT FROM AUTHOR]