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Open‐shell organic radical semiconductor materials have received increasing attention in recent years due to their distinctive properties compared to the traditional materials with closed‐shell singlet ground state. However, their poor chemical and photothermal stability in ambient conditions remains a significant challenge, primarily owing to their high reactivity with oxygen. Herein, a novel open‐shell poly(3,4‐dioxythiophene) radical PTTO2 is designed and readily synthesized for the first time using low‐cost raw material via a straightforward BBr3‐demethylation of the copolymer PTTOMe2 precursor. The open‐shell character of PTTO2 is carefully studied and confirmed via the signal‐silent 1H nuclear magnetic resonance spectrum, highly enhanced electron spin resonance signal compared with PTTOMe2, as well as the ultra‐wide ultraviolet‐visible‐near nfraredUV–vis–NIR absorption and other technologies. Interestingly, the powder of PTTO2 exhibits an extraordinary absorption range spanning from 300 to 2500 nm and can reach 274 °C under the irradiation of 1.2 W cm−2, substantially higher than the 108 °C achieved by PTTOMe2. The low‐cost PTTO2 stands as one of the best photothermal conversion materials among the pure organic photothermal materials and provides a new scaffold for the design of stable non‐doped open‐shell polymers. [ABSTRACT FROM AUTHOR]

The intensive interest in expanded porphyrins can be attributed to their appealing photoelectric and coordination behavior. In this work, an N‐confused heptaphyrin 1 was synthesized by an acid‐catalyzed [3+4] condensation reaction. The introduction of an N‐confused pyrrolic unit into the heptaphyrin macrocycle led to the formation of a figure‐eight‐like conformation with nonsymmetrical "NNNN" and "NNNC" coordination cavities employable for bimetallic coordination. As a result, chelation of 1 with Zn(II) and Cu(II) afforded mono‐Zn(II) complex 2 and bis‐Cu(II) complex 3, respectively, with the metal atoms exhibiting distorted square‐planar geometries. In complex 3, an oxygen atom is attached to the α‐C atom of N‐confused pyrrole D, and thus the N and C atoms of ring D participate in coordination within the two cavities. Interestingly, treatment of 1 with Cs2CO3 in MeOH resulted in regioselective substitution of all the seven para‐F atoms in the meso‐C6F5 groups as well as the α‐H of ring D by eight methoxy moieties. Complex 3 displays a red‐shifted absorption band edge of ca. 2200 nm, compared to that of ca. 1600 nm observed for 1. This work provides an example of incorporating an N‐confused pyrrole to construct expanded porphyrins with distinctive coordination behavior and tunable NIR absorption. [ABSTRACT FROM AUTHOR]

The design of near‐infrared photosensitizers with high photodynamic and photothermal synergistic therapeutic properties is of great significance for tumor therapy. In this study, An‐cyclic‐BDP with excellent near‐infrared absorption (ε = 1.94 × 105 m−1 cm−1 at 804 nm) is prepared using a dual strategy of twisted π‐conjugated system induction (T‐π‐CSI) and spin‐orbit charge transfer (SOCT). Theoretical calculations, steady‐state and transient absorption spectra are used to investigate the intrinsic regulatory mechanisms between molecular structure and intersystem crossing (ISC) capacity. The results indicate that the application of the T‐π‐CSI and SOCT approach can be superimposed to increase ISC capacity and the triplet lifetime of An‐cyclic‐BDP (τ = 2961 ps). Electron paramagnetic resonance (EPR) results confirm that An‐cyclic‐BDP has the ability to generate hydroxyl radical (·OH) and singlet oxygen (1O2). Furthermore, the calculated 1O2 yield of An‐cyclic‐BDP is found to be 13%. The experimental results of the photothermal conversion indicates that An‐cyclic‐BDP exhibits a photothermal conversion efficiency of up to 48%. In vitro cell experiments demonstrate that An‐cyclic‐BDP‐NPs, constructed by encapsulating An‐cyclic‐BDP with DSPE‐mPEG2000, exhibit excellent biocompatibility and tumor cell‐killing ability. Therefore, the strong near‐IR absorption photosensitizer prepared in this study exhibits significant potential for application in the area of photodynamic and photothermal synergistic therapy. [ABSTRACT FROM AUTHOR]

Organic photovoltaics (OPVs) represent one of the most promising photovoltaic technologies owing to their high capacity to convert solar energy to electricity. With the continuous structure upgradation of photovoltaic materials, especially that of non‐fullerene acceptors (NFAs), the OPV field has witnessed rapid progress with power conversion efficiency (PCE) exceeding 19%. However, it remains challenging to overcome the intrinsic trade‐off between the photocurrent and photovoltage, restricting the further promotion of the OPV efficiency. In this regard, it is urgent to further tailor the structure of NFAs to broaden their absorption spectra while mitigating the energy loss of relevant devices concomitantly. Heteroatom substitution on the fused‐ring π‐core of NFAs is an efficient way to achieve this goal. In addition to improve the near‐infrared light harvest by strengthening the intramolecular charge transfer, it can also enhance the molecular stacking via forming multiple noncovalent interactions, which is favorable for reducing the energetic disorder. Therefore, in this review we focus on the design rules of NFAs, including the polymerized NFAs, of which the core moiety is substituted by various kinds of heteroatoms. We also afford a comprehensive understanding on the structure–property−performance relationships of these NFAs. Finally, we anticipate the challenges restricting the efficiency promotion and industrial utilization of OPV, and provide potential solutions based on the further heteroatom optimization on NFA core‐moiety. [ABSTRACT FROM AUTHOR]

Context: For the advancement in fields of organic and perovskite solar cells, various techniques of structural alterations are being employed on previously reported chromophores. In this study, the end-capped engineering is carried out on DBT-4F (R) by modifying terminal acceptors to improve optoelectronic and photovoltaic attributes. Seven molecules (AD1-AD7) are modeled using different push–pull acceptors. DFT/B3LYP/6-31G along with its time-dependent approach (TD-DFT) are on a payroll to investigate ground state geometries, absorption maxima (λmax), energy gap (Eg), excitation energy (Ex), internal reorganization energy, light harvesting efficiency (LHE), dielectric constant, open circuit voltage (VOC), fill factor (FF), etc. of OSCs. AD1 displayed the lowest band gap (1.76 eV), highest λmax (876 nm), lowest Ex (1.41 eV), and lowest binding energy (0.21 eV). Among various calculated parameters, all of the sketched molecules demonstrated greater dielectric constant when compared to R. The highest dielectric constant was exhibited by AD3 (56.26). AD5 exhibited maximum LHE (0.9980). Lower reorganization energies demonstrated improved charge mobility. AD5 and AD7 (1.63 and 1.68 eV) have higher values of VOC than R (1.51 eV). All novel molecules having outperforming attributes will be better candidates to enhance the efficacy of OSCs for future use. Methods: Precisely, a DFT and TD-DFT analysis on all of the proposed organic molecules were conducted, using the functional MPW1PW91 at 6-31G (d,p) basis set to examine their optoelectronic aspects, additionally the solvent-state computations were studied with a TD-SCF simulation. For all these simulations, Guassian 09 and GuassView 5.0 were employed. Moreover, the Origin 6.0, Multiwfn 3.8, and PyMOlyze 1.1 software were utilized for the visual depiction of the graphs of absorption, TDM, and DOS, respectively of the studied molecules. A number of crucial aspects such as FMOs, bandgaps, light-harvesting efficiency, electrostatic potential, dipole moment, ionization potential, open-circuit voltage, fill factor, binding energy, interaction coefficient, chemical hardness–softness, and electrophilicity index were also investigated for the studied molecules. [ABSTRACT FROM AUTHOR]

Abstract Open‐shell organic radical semiconductor materials have received increasing attention in recent years due to their distinctive properties compared to the traditional materials with closed‐shell singlet ground state. However, their poor chemical and photothermal stability in ambient conditions remains a significant challenge, primarily owing to their high reactivity with oxygen. Herein, a novel open‐shell poly(3,4‐dioxythiophene) radical PTTO2 is designed and readily synthesized for the first time using low‐cost raw material via a straightforward BBr3‐demethylation of the copolymer PTTOMe2 precursor. The open‐shell character of PTTO2 is carefully studied and confirmed via the signal‐silent 1H nuclear magnetic resonance spectrum, highly enhanced electron spin resonance signal compared with PTTOMe2, as well as the ultra‐wide ultraviolet‐visible‐near nfraredUV–vis–NIR absorption and other technologies. Interestingly, the powder of PTTO2 exhibits an extraordinary absorption range spanning from 300 to 2500 nm and can reach 274 °C under the irradiation of 1.2 W cm−2, substantially higher than the 108 °C achieved by PTTOMe2. The low‐cost PTTO2 stands as one of the best photothermal conversion materials among the pure organic photothermal materials and provides a new scaffold for the design of stable non‐doped open‐shell polymers.

Abstract Recent optical analyses of cesium-doped hexagonal tungsten bronze have accurately replicated the absorption peak and identified both plasmonic and polaronic absorptions in the near-infrared region, which have been exploited in various technological applications. However, the absorption peaks of tungsten oxides and bronzes have not generally been reproduced well, including those of the homologous potassium- and rubidium-doped hexagonal tungsten bronzes that lacked evidence of polaronic subpeaks. The present study reports a modified and simplified Mie scattering integration method which incorporates the ensemble inhomogeneity effect and allows precise peak decomposition and determination of the physical parameters of nanoparticles. The decomposed peaks were interpreted in terms of electronic structures, screening effect, and modified dielectric functions. The analysis revealed that the plasma frequencies, polaron energies, and the number of oxygen vacancies decrease in the dopant order Cs → Rb → K. The coexistence of plasmonic and polaronic excitations was confirmed for all the alkali-doped hexagonal tungsten bronzes.

Abstract Organic photovoltaics (OPVs) represent one of the most promising photovoltaic technologies owing to their high capacity to convert solar energy to electricity. With the continuous structure upgradation of photovoltaic materials, especially that of non‐fullerene acceptors (NFAs), the OPV field has witnessed rapid progress with power conversion efficiency (PCE) exceeding 19%. However, it remains challenging to overcome the intrinsic trade‐off between the photocurrent and photovoltage, restricting the further promotion of the OPV efficiency. In this regard, it is urgent to further tailor the structure of NFAs to broaden their absorption spectra while mitigating the energy loss of relevant devices concomitantly. Heteroatom substitution on the fused‐ring π‐core of NFAs is an efficient way to achieve this goal. In addition to improve the near‐infrared light harvest by strengthening the intramolecular charge transfer, it can also enhance the molecular stacking via forming multiple noncovalent interactions, which is favorable for reducing the energetic disorder. Therefore, in this review we focus on the design rules of NFAs, including the polymerized NFAs, of which the core moiety is substituted by various kinds of heteroatoms. We also afford a comprehensive understanding on the structure–property−performance relationships of these NFAs. Finally, we anticipate the challenges restricting the efficiency promotion and industrial utilization of OPV, and provide potential solutions based on the further heteroatom optimization on NFA core‐moiety.

Organic donor‐acceptor semiconductors exhibit great potential in photothermal conversion. However, it is still challenging to achieve pure organic materials with broad absorption comparable with inorganic materials such as graphene. Herein, two D‐A‐D type DPA‐BT‐O4 and NDI‐TPA‐O4 and three D‐A‐π‐A‐D type Th‐O4, Th2‐O4, and IDT‐O4 were readily prepared via two high‐yield steps and simple air oxidization. The stability can be attributed to their multiple resonance structures based on the aromatic nitric acid radical mechanism. Compared with the D‐A‐D radicals, the conjugation extension of the D‐A‐π‐A‐D radicals endows them with a narrowed band gap and broad absorption in powder. Interestingly, the IDT‐O4 powder with aggregation‐induced radical effect exhibits broad absorption between 300 and 2500 nm, which is comparable with graphene and other inorganic materials. Under irradiation of 0.9 W/cm2 (808 nm), the temperature of IDT‐O4 powder rises to 250°C within 60 s. The water evaporation conversion efficiency of 94.38 % and an evaporation rate of 1.365 kg/m2 h−1 under one sun illumination were achieved. IDT‐O4 stands as one of the most efficient photothermal conversion materials among pure organic materials via a rational design strategy. [ABSTRACT FROM AUTHOR]

Tumor hypoxia severely limits the therapeutic efficacy of photodynamic therapy (PDT) for solid tumors, which is highly dependent on tissue oxygen concentration. In this study, we developed a platinum(II)-acetylide-based metallacycle compound bearing six 1,4-dimethylnaphthalenes (DMN) groups, and controlled the photodynamic and photothermal effects of the compound by adjusting the power of 730 nm laser to achieve reversible sensitization, storage and release of 1O2 within a single molecule. The compound formed nanoparticles by self-assembly and exhibited good water solubility and biocompatibility. Under laser irradiation, the strong spin-orbit coupling of platinum atoms in the metallacycle facilitated 1O2 generation. The produced 1O2 was captured by the DMN carriers and transported into the hypoxic tumor, where 1O2 release was triggered owing to the good photothermal effect of the extended conjugation of the metallacycle. During therapy, the metallacycle serving as a photosensitizer, 1O2 carrier, and photothermal reagent, achieved the synergistic therapy of PDT/PTT, demonstrating the versatility of the metallacycle. This study proposes a new strategy to develop phototherapy agents that are suitable for hypoxic tumors. [ABSTRACT FROM AUTHOR]

Abstract Organic donor‐acceptor semiconductors exhibit great potential in photothermal conversion. However, it is still challenging to achieve pure organic materials with broad absorption comparable with inorganic materials such as graphene. Herein, two D‐A‐D type DPA‐BT‐O4 and NDI‐TPA‐O4 and three D‐A‐π‐A‐D type Th‐O4, Th2‐O4, and IDT‐O4 were readily prepared via two high‐yield steps and simple air oxidization. The stability can be attributed to their multiple resonance structures based on the aromatic nitric acid radical mechanism. Compared with the D‐A‐D radicals, the conjugation extension of the D‐A‐π‐A‐D radicals endows them with a narrowed band gap and broad absorption in powder. Interestingly, the IDT‐O4 powder with aggregation‐induced radical effect exhibits broad absorption between 300 and 2500 nm, which is comparable with graphene and other inorganic materials. Under irradiation of 0.9 W/cm2 (808 nm), the temperature of IDT‐O4 powder rises to 250°C within 60 s. The water evaporation conversion efficiency of 94.38 % and an evaporation rate of 1.365 kg/m2 h−1 under one sun illumination were achieved. IDT‐O4 stands as one of the most efficient photothermal conversion materials among pure organic materials via a rational design strategy.

Porphyrins are attracting increasing attention in materials science and photochemistry owing to their unique properties and diverse applications. This study focuses on modifying and tuning the absorption properties of porphyrins, specifically those of quinoidal porphyrins, to extend their spectral range into the near‐infrared (NIR) region. We report the synthesis and structural and physical properties of quinone compounds derived from doubly and triply linked diporphyrins and their metal complexes. Doubly linked diporphyrinquinone exhibits broad panchromatic absorption properties in solution owing to its low symmetry. Metal complexation markedly extends its absorption range into the near‐infrared region. In contrast, the metal complexes of the triply linked diporphyrinquinones exhibit sharp and strong absorption bands in the visible to near‐infrared region owing to their higher symmetry. The longest absorption wavelength of the triply linked diporphyrinquinones was approximately 1500 nm, which was significantly more red‐shifted than that of the doubly linked ones. [ABSTRACT FROM AUTHOR]

Five gallium naphthalocyanines, Cl-GaNcTl, OH-GaNcTl, OSiR3-GaNcTI, F5Ph-GaNcTI and QL-GaNcTI, have been designed and synthesized as acceptor materials for bulk heterojunction organic solar cells (BHJ OSCs) . They exhibit strong near-infrared absorption at 300~1100 nm, a high maximum extinction coefficient of 6. 18×105 L/ (mol·cm), a low minimum unoccupied molecular orbital (LUMO) energy level of -3. 9 eV, and good thermal stability (Td＞320 ℃) . The introduction of long chain substituents in the axial direction of naphthalocyanine is found to be effective in decreasing molecular aggregation. All of them could be used as acceptor materials for bulk-phase heterojunction organic solar cells. [ABSTRACT FROM AUTHOR]

In order to solve the problem of near-infrared (NIR) absorbance attenuation of silicon, a method of preparing gold nanoparticles (AuNPs) on the micro–nano-structured black silicon (B-Si) is proposed. In this study, the local surface plasmon resonance (LSPR) of AuNPs excited by a light field is used to achieve B-Si materials with broad spectrum and high absorption. The results show that nanometer B-Si composited with 25-nm AuNPs has an average absorption of 98.6% in the spectral range of 400–1100 nm and 97.8% in the spectral range of 1100–2500 nm. Compared with ordinary B-Si, the absorption spectrum is broadened from 400–1100 nm to 400–2500 nm, and the absorption is increased from 90.1 to 97.8% at 1100–2500 nm. It is possible to use the B-Si materials in the field of NIR-enhanced photoelectric detection and micro-optical night vision imaging due to the low cost, high compatibility, and reliability. [ABSTRACT FROM AUTHOR]

Photodynamic therapy (PDT) has shown promising development due to its low toxicity, high selectivity and low side effects. However, the effectiveness of PDT is dependent on the concentration of oxygen and tumor cells have a hypoxia microenvironment that reduces the therapeutic effect of PDT. Therefore, near-infrared absorbing conjugated copolymers with perfluorocarbon side chains, 2,5-bis(2- octyldodecyl)-3,6-di(thiophen-2-yl)-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione-co-2,5-thiophene-co-9,9-bis(N-methylperfluorohexylsulfonamidoethyl propionate)- fluorene copolymers, with the ability to generate singlet oxygen under hypoxia conditions were designed and synthesized. The structures of the copolymers were characterized by Fourier transform infrared spectrometer (FTIR) and proton nuclear magnetic resonance spectrum (1HNMR). The singlet oxygen generation ability of the copolymers and corresponding nanoparticles under organic solvents and aqueous conditions was investigated. The results show that the absorption wavelengths of the fluorine-containing conjugated copolymers are greater than 650 nm and they show strong absorption in near-infrared region. The perfluorocarbon (PFC) side chain endows the copolymers with high singlet oxygen generation capability. As the content of fluorine-containing structural units increases, the generation capability of singlet oxygen increases. When the proportion of fluorine-containing structural units is 35%mol (P3-F35%), the copolymer has the singlet oxygen quantum yield of 36.29%. And the singlet oxygen generation capability of the fluorine-containing copolymers is significantly enhanced even under hypoxia conditions. The nanoparticle of fluorine-containing conjugated polymer shows good singlet oxygen generation ability in aqueous suspension. The results of this study indicate that introducing fluorine-containing structure unit into near-infrared absorbing conjugated copolymers is an effective way to enhance the singlet oxygen generation capability of copolymers, which may have broad application prospects in the field of photodynamic therapy. [ABSTRACT FROM AUTHOR]

The relationship between the overall electronic structure of π‐conjugated molecules and the arrangement of their constituent elements is of fundamental importance. Establishing rational design guidelines for conjugated hydrocarbons with narrow HOMO‐LUMO gaps is useful to develop near‐infrared (NIR) responsive dyes and redox‐active materials. This study describes the synthesis and properties of three conjugated hydrocarbons, i. e. an indenonaphthoperylene, an indenoterrylene, and a diindenoterrylene. These molecules exhibit NIR absorption despite the absence of significant antiaromaticity and diradical character. Notably, the indenonaphthoperylene exhibits red‐to‐NIR emission in the 620–850 nm region. The indenoterrylene and the diindenoterrylene exhibit NIR absorption tailing to 870 and 940 nm, respectively. Moreover, the effect of the π‐extension of indenoperylene is disclosed in order to propose guidelines for achieving a narrow HOMO‐LUMO gap with negligible antiaromaticity and diradical character. [ABSTRACT FROM AUTHOR]

2,7,12,17‐Tetrakis(pinacolatoboryl) NiII porphyrin 5 Ni was synthesized in 75 % yield by Ir‐catalyzed borylation of porphine followed by NiII metalation and has been demonstrated to be a useful synthon, giving 2,7,12,17‐tetraaryated NiII porphyrins 6 a–d, peripherally octaarylated NiII porphyrins 8 a–d, quadruply bridged face‐to‐face non‐offset NiII‐porphyrin dimer 12, and cross‐shaped β‐meso singly linked porphyrin pentamers and nonamers. Oxidation of cross‐shaped β‐meso singly linked porphyrin pentamers 14 Ni and 14 Zn gave fused pentameric tapes 15 Ni and 15 Zn. The structures of 12, 14 Zn, and 15 Ni have been revealed by X‐ray diffraction analysis. Optical separation of 12 has been accomplished, showing a bisignate coupling pattern for exciton‐coupled blue‐shifted Soret band. Pentameric porphyrin tape 15 Zn exhibits a red‐shifted absorption band at 1156 nm and seven reversible redox waves. [ABSTRACT FROM AUTHOR]

Context: Density functional theory (DFT) method was employed to investigate the electronic structure properties, excited state dynamics, charge transfer, and photovoltaic potential of benzo [1,2,5] thiadiazole fused to 3,7-dimethyl-3a,6,7,7b-tetrahydro-5H-thieno[2′,3′:4,5]thieno[3,2-b]pyrrole to form 3,9,12,13-tetramethyl-12,13-dihydro-[1,2,5]thiadiazolo[3,4-e]thieno[2″,3″:4,5]pyrrolo[3.2-g]thieno[2′,3′:4,5]thieno[3,2-b]indole as the acceptor (A), bridge with thiophene as π-spacer to the donor moieties (D) which are 2,3-dihydrobenzo [b]thiophene-6-carboxylic acid (M4) and functionalized R, M1, M2, M3, and M5 to give a D-π-A-π-D. Here is the reverse combination for our molecules: the A-π-D-π-A type of chromophore configuration. It is also observed that tuning the dono-bridge configuration significantly increases the ease of charge transfer as the energy gap decreases in the order of 1.29 eV in M4 < 1.59 eV in M3 < 1.67 eV < 1.99 in M2 and 2.06 eV. The reorganization energy (RE) of M3 (0.0031) and M5 (0.0031) indicates an increase in the order of M3 > M5 > R > M2 > M4 > M1. The HOMO-LUMO indicates that the reactivity decreased, while the stability increased for the reference R at 0.990 eV, compared to the designed molecules M1–M5, with M1 being the least stable at 0.970 eV, while M4 exhibited the highest stability at 1.550 eV. The stability of the designed molecule decreased in the order of M4:1.550 > M3:1.257 > M5:1.197 > M2:1.010 > M1:0.970. Therefore, all results point to the electron-deficient core as an effective end-capped electron acceptor in M1–M5 compounds. As the ideal pair for successfully optimizing optoelectronic properties by reducing the HOMO-LUMO energy levels, reorganization energy, and binding energy and enhancing the absorption maximum and open-circuit voltage values in these designed molecules. Methods: DFT and TDDFT calculations were performed with Gaussian 16 program. The modelled compounds were optimized fully using the CAM-B3LYP, WB97XD, B3LYP, and MPW1PW91 functionals with the 6-31 G (d,p) basis set. The graphs for the density of states were plotted using the PyMOlyze software. Other molecular properties like the transition density matrix (TDM) and electron density difference maps (EDD) were rendered via the Multiwfn software. [ABSTRACT FROM AUTHOR]

The double-bridged N–B ← N bipyridine unit (BNBP) with boron-nitrogen covalent bond and coordination bond can reduce the electronic energy level of the π-conjugated system, resulting in a reduction of band gap and a red shift in the absorption spectrum. Embedding the BNBP building block into organic optoelectronic materials provides a novel possibility in molecule design. In this paper, under the guidance of density functional theory (DFT) calculations, a series of 3D "airfoil-shaped" small molecule donors (SMDs) have been designed and successfully synthesized through Sonogashira, Suzuki and Stille coupling reactions. BNBP is adopted as the central electron-withdrawing unit and strong electron-rich triphenylamine (TPA) as the terminal group. The novel "airfoil-shaped" structure plays a supporting role in reducing the carrier recombination in the active layer. It reveals that molecular design engineering can achieve the expected results by the following steps: Firstly, the introduction of electron-rich alkoxy groups into the end of TPA through side chain engineering helps to improve the solubility and film-forming properties of the materials. Then, the π-bridge regulation not only extends the conjugate structure, but also plays a crucial role in the regulation of photovoltaic properties. It is worth noting that the compound BNBP(3TTPA) 2 was synthesized by introducing thiophene oligomer into BNBP-based SMDs for the first time. Finally, the compound BNBP(EDPPTPA) 2 was constructed by combining BNBP with DPP dye unit. Its narrow band gap is only 1.36 eV, which is one of the narrowest band gaps in small molecular organic-boron materials. In particular, compared with the starting compound BNBP(ETPA) 2 , the synergistic effects of DPP and BNBP broaden the edge absorption wavelength to 814 nm, resulting in a red shift of 170 nm. The power conversion efficiency (PCE) of 4.48 % is obtained in BNBP(EDPPTPA) 2 -based bulk heterojunction (BHJ) organic solar cells (OSCs), which is more than twice that of reference compound BNBP(ETPA) 2. This work provides important references for the future development of 3D BNBP-based organic-boron SMDs and the structural regulation of materials through molecular engineering. A series of 3D "airfoil-shaped" small molecular donors (SMDs) were designed and synthesized based on double-bridged N–B ← N bipyridine (BNBP). In which BNBP(3TTPA) 2 was synthesized by introducing thiophene oligomer into BNBP-based SMDs for the first time. The DPP-bridged compound BNBP(EDPPTPA) 2 was constructed with a narrow band gap of 1.36 eV. In particular, compared with the starting compound BNBP(ETPA) 2 , the synergistic effects of DPP and BNBP broaden the absorption wavelength to 814 nm, resulting in a red shift of 170 nm. The power conversion efficiency (PCE) of 4.48 % is obtained in BNBP(EDPPTPA) 2 -based device, which is more than twice that of reference compound BNBP(ETPA) 2. This work provides important references for the development of 3D BNBP-based organic-boron SMDs and structural regulation through molecular engineering. [Display omitted] • A series of BNBP-based 3D "airfoil-shaped" SMDs were designed and synthesized. • Thiophene oligomer was introduced to organic-boron SMDs for the first time. • The DPP-bridged compound BNBP(EDPPTPA) 2 was constructed with a narrow E g of 1.36 eV. • The synergistic effect of DPP and BNBP makes the PCE of BNBP(EDPPTPA) 2 -based devices increase to 4.48 %. • BNBP(EDPPTPA) 2 broadens the absorption to 814 nm, resulting in a red shift of 170 nm. [ABSTRACT FROM AUTHOR]

The imination of a cage‐opened fullerene C60 derivative was examined using N,N‐dimethyl‐1,4‐phenylenediamine. The desired imine derivative showed a remarkably intense near‐infrared (NIR) absorption band (λedge=1050 nm). According to theoretical calculations, the longest wavelength absorption is assignable to the HOMO→LUMO transition with a strong charge‐transfer character, in which the HOMO localizes on the introduced imine moiety while the high LUMO coefficients can be seen over the entire C60 skeleton. It should be noted that the two reduced compounds bearing an amine or methylene group were also formed in the reaction producing the imine derivative, the former of which again showed NIR absorption tailing to 1200 nm. In this reduction, the hydride source is considered to be α‐hydrogen of the diamine so that the use of N,N,N',N'‐tetramethyl‐1,4‐phenylenediamine increased the yield of the methylene derivative up to 20%. [ABSTRACT FROM AUTHOR]

The one‐pot self‐coupling reaction of 3‐amino‐5‐bromo‐BODIPY 9 under Buchwald–Hartwig amination conditions gave nitrogen‐bridged cyclic BODIPY tetramer 10, pentamer 11, and hexamer 12. Oxidation of 10, 11, and 12 in the presence of alkali metal ions provided 13, 15, and 16, respectively, as the first examples of expanded azaporphyrins possessing more than six pyrrole rings. Curiously, the oxidation even in the absence of alkali metal ions gave the same complexes as a result of spontaneous complexation. 10–12 showed large association constants (104–106 M−1) with K+ and Na+, but the spontaneous complexations were not observed, indicating the extremely high affinities of 13–16 toward alkali metal ions, which can be ascribed to the multiple and effective ion–dipole interaction of the alkali metal ion with the negatively polarized F atoms of the BF2 walls surrounding the cavity. Importantly, 13, 14, and 15 show diatropic ring currents as a result of global aromaticity. [ABSTRACT FROM AUTHOR]

Carbon dots (CDs) have attracted significant interest as one of the most emerging photoluminescence (PL) nanomaterials. However, the realization of CDs with dominant near‐infrared (NIR) absorption/emission peaks in aqueous solution remains a great challenge. Herein, CDs with both main NIR absorption bands at 720 nm and NIR emission bands at 745 nm in an aqueous solution are fabricated for the first time by fusing large conjugated perylene derivatives under solvothermal treatment. With post‐surface engineering, the polyethyleneimine modified CDs (PEI‐CDs) exhibit enhanced PL quantum yields (PLQY) up to 8.3% and 18.8% in bovine serum albumin aqueous and DMF solutions, which is the highest PLQY of CDs in NIR region under NIR excitation. Density functional theory calculations support the strategy of fusing large conjugated perylene derivatives to achieve NIR emissions from CDs. Compared to the commercial NIR dye Indocyanine green, PEI‐CDs exhibit excellent photostability and much lower cost. Furthermore, the obtained PEI‐CDs illustrate the advantages of remarkable two‐photon NIR angiography and in vivo NIR fluorescence bioimaging. This work demonstrates a promising strategy of fusing large conjugated molecules for preparing CDs with strong NIR absorption/emission to promote their bioimaging applications. [ABSTRACT FROM AUTHOR]

We synthesize and compare four near-infrared absorbing fused-ring electron acceptors named as nTTIC (n=2, 3, 4, and 5), based on different number of thieno[3,2-b]thiophene (TT) unit as the electron-donating core. With increasing the TT unit, absorption spectrum of the TTIC series red shifts, and the highest occupied molecular orbital (HOMO) upshifts notably. It is worth noting that 4TTIC and 5TTIC exhibit absorption edges approaching 1100 nm, which is the photoresponse limit of solar cells based on crystal silicon. When the TTIC series acceptors are blended with polymer donor PM6, the binary-blend organic solar cells based on 3TTIC show the best power conversion efficiency (PCE) of 13.1%. In contrast, 2TTIC-based devices exhibit relatively lower PCE of 8.32%, mainly caused by the larger energy loss and blue-shifted absorption. Due to insufficient driving force of charge separation caused by very high HOMO, 4TTIC and 5TTIC show poor PCEs lower than 3%. [ABSTRACT FROM AUTHOR]

The preparation of radicals with intense and redox‐switchable absorption beyond 1000 nm is a long‐standing challenge in the chemistry of functional dyes. Here we report the preparation of a series of unprecedented stable neutral nickel(II) and copper(II) complexes of "Manitoba dipyrromethenes" (MB‐DIPYs) in which the organic chromophore is present in the radical‐anion state. The new stable radicals have an intense absorption at λmax∼1300 nm and can be either oxidized to regular [MII(MB‐DIPY)]+ (M=Cu or Ni) or reduced to [MII(MB‐DIPY)]− compounds. The radical nature of the stable [MII(MB‐DIPY)] complexes was confirmed by EPR spectroscopy with additional insight into their electronic structure obtained by UV‐Vis spectroscopy, electro‐ and spectroelectrochemistry, magnetic measurements, and X‐ray crystallography. The electronic structures and spectroscopic properties of the radical‐based chromophores were also probed by density functional theory (DFT) and time‐dependent DFT (TDDFT) calculations. These nickel(II) and copper(II) complexes represent the first stable radical compounds with a MB‐DIPY ligand. [ABSTRACT FROM AUTHOR]

Abstract Carbon dots (CDs) have attracted significant interest as one of the most emerging photoluminescence (PL) nanomaterials. However, the realization of CDs with dominant near‐infrared (NIR) absorption/emission peaks in aqueous solution remains a great challenge. Herein, CDs with both main NIR absorption bands at 720 nm and NIR emission bands at 745 nm in an aqueous solution are fabricated for the first time by fusing large conjugated perylene derivatives under solvothermal treatment. With post‐surface engineering, the polyethyleneimine modified CDs (PEI‐CDs) exhibit enhanced PL quantum yields (PLQY) up to 8.3% and 18.8% in bovine serum albumin aqueous and DMF solutions, which is the highest PLQY of CDs in NIR region under NIR excitation. Density functional theory calculations support the strategy of fusing large conjugated perylene derivatives to achieve NIR emissions from CDs. Compared to the commercial NIR dye Indocyanine green, PEI‐CDs exhibit excellent photostability and much lower cost. Furthermore, the obtained PEI‐CDs illustrate the advantages of remarkable two‐photon NIR angiography and in vivo NIR fluorescence bioimaging. This work demonstrates a promising strategy of fusing large conjugated molecules for preparing CDs with strong NIR absorption/emission to promote their bioimaging applications.

Numerous photothermal agents (PTAs) require high-intensity and long-duration laser excitation for photothermal therapy (PTT), resulting in light damage to healthy skin and tissue as well as limiting their biomedical applications. Integrating desirable near-infrared (NIR) absorption and high photothermal conversion efficiency (PCE) into a single small-molecule PTA is an important prerequisite for realizing efficient PTT, but is a serious challenge. Herein, through molecular engineering strategy, an acceptor-donor-acceptor (A-D-A) type PTA (ADA3) was readily developed for 808 nm laser-driving photothermal imaging and PTT of tumor. Theoretical calculations and experiment results show molecular engineering strategy is significant in regulating the structure and energy gap of PTAs, so as to effectively induce a narrow band gap for NIR absorption and further optimize photothermal properties. ADA3 possesses molar extinction coefficient of 3.1 × 104 M−1 cm−1 at 808 nm, followed being assembled into nanoparticles, ADA3-NPs show high PCE of 80.3%. In vivo experiments indicate that ADA3-NPs have excellent antitumor capability under one-time, low-intensity and short-duration (808 nm, 330 mW/cm2, 3 min) laser irradiation. Therefore, this work definitely exemplifies the enormous potential of molecular engineering strategy and provides an effective method for developing small-molecule PTAs. [Display omitted] • Improving the photothermal properties of PTA through molecular engineering strategy. • Integrating desirable NIR absorption and high PCE into a single small-molecule PTA. • Tumor ablation by one-time, low-intensity and short-duration NIR laser irradiation. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel photocatalyst (ZnPc/PCN) with near-infrared absorption ability (400–800 nm) was synthesized by π-π stacking. • The ZnPc/PCN with a strong built-in electric field exhibits efficient photogenerated charge separation. • The AQY of photocatalytic H 2 O 2 production by ZnPc/PCN under 800 nm irradiation was 1.11 %. • A stable ZnPc aggregates as photocatalysts was designed. Hydrogen peroxide (H 2 O 2) serves as a critical industrial chemical and potential energy carrier. Photocatalytic synthesis presents a viable alternative to the anthraquinone process, yet existing catalyst systems exhibit restricted sunlight wavelength responses and inadequate activity. In this study, zinc phthalocyanine/polymer carbon nitride (ZnPc/PCN) S-scheme heterojunction formation extends the photocatalyst's light absorption range to the near-infrared region (400–800 nm) and generates an internal electric field at the interface, facilitating photogenerated carrier separation and transfer. ZnPc/PCN exhibits an AQY of 1.11 % for H 2 O 2 production under 800 nm irradiation. The optimized ZnPc/PCN yields 1.87 mM H 2 O 2 , surpassing the original PCN and ZnPc by 1.36 and 93.5 times, respectively·H 2 O 2 production remains above 1.5 mM (80 %) after five cycles, demonstrating ZnPc/PCN stability. Detection of intermediate ·OOH suggests H 2 O 2 production via 2 e- oxygen reduction processes. This research offers novel insights for designing near-infrared absorbing photocatalysts. [ABSTRACT FROM AUTHOR]

Anti‐Stokes Raman spectroscopy is an excellent method to suppress optical backgrounds from Raman scatters and surrounding materials, even in electronic resonance conditions. The upshift of scattered light can avoid the fluorescence or phosphorescence that is usually red‐shifted with respect to the excitation wavelength. However, this method's competence is circumscribed by its low scattering efficiency, which results from an insufficient population of upper vibrational states that obey temperature‐dependent Boltzmann statistics. To overcome this limitation, we propose that the mode‐selective absorption of overtone or combination vibrations leads to enhanced anti‐Stokes Raman scattering under simultaneous optical pumping and Raman excitation. In this work, we applied near‐infrared (NIR) pumping resonant with vibrational overtones of nonfluorescent systems. Vibrationally resonant pumping is efficient for population transfer, and the excess energy is thermodynamically distributed over all fundamental vibrations. Furthermore, we present that NIR absorbing molecules can be employed as matrices to amplify anti‐Stokes Raman signals of weak scattering targets. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fused tris(thienothiophene)-based acceptors with strong absorption in NIR region. • Halogenation effects of Cl and Br atoms on end groups. • Manipulating the intermolecular stacking and charge transport for OSCs. The fused-ring electron acceptors (FREAs) with A-D-A structures have experienced rapid development recent years. However, these FREAs still suffer the relative limited absorption in the near-infrared (NIR) region thus leading to low utilization of the solar light. Herein, two FREAs with strong absorption in NIR region, namely 6TIC-2Cl and 6TIC-2Br, were designed and synthesized by employing the fused tris(thienothiophene) (3TT) unit as the "D" along with 2-(5(6)-chloro-3-oxo-2,3-dihydro-1H-inden-1-ylidene) malononitrile (DCI-Cl) and 2-(5(6)-bromo-3-oxo-2,3-dihydro-1H-inden-1-ylidene) malononitrile (DCI-Br) as the end-groups, respectively. The strong electron-donating and molecular packing ability of 3TT and the enhanced electron-withdrawing ability of the halogenated terminal groups facilitated the intramolecular charge transfer thus bathochromic-shifting the absorption edges of 6TIC-2Cl and 6TIC-2Br to 940 nm and 934 nm, respectively. Consequently, the best-performing organic solar cells (OSCs) based on PBDB-T:6TIC-2Cl and PBDB-T:6TIC-2Br achieved the impressive short-circuit current density (J SC) of 23.83 mA cm−2 and 22.74 mA cm−2. In addition, the results showed that brominated terminal group was more beneficial to obtain a higher open-circuit voltage (V OC) and fill factor (FF) than the chlorinated end-group, which contributed to a decent PCE of 11.77%. This work revealed the impact of halogen atoms in the terminal group with 3TT units as core on the organic photovoltaic performance and provided guidance for designing SMAs with strong absorption in the visible-NIR region. [ABSTRACT FROM AUTHOR]

DNA-wrapped single-walled carbon nanotubes (DNA-SWCNTs) in stable dispersion are expected to be used as biosensors in the future, because they have the property of absorption of light in the near infrared (NIR) region, which is safe for the human body. However, this practical application requires the understanding of the DNA-SWCNTs' detailed response characteristics. The purpose of this study is to predict, in detail, the response characteristics of the absorption spectra that result when the antioxidant catechin is added to oxidized DNA-SWCNTs, from a small amount of experimental data. Therefore, in the present study, we predicted the characteristics of the absorption spectra of DNA-SWCNTs using the Bayesian regularization backpropagation neural network (BRBPNN) model. The BRBPNN model was trained with the catechin concentration and initial absorption peaks as inputs and the absorption spectra after catechin addition as outputs. The accuracy of the predicted absorption peaks and wavelengths after the addition of catechin, as predicted by the BRBPNN model, was within 1% of the error of the experimental data. By inputting the catechin concentrations under hundreds of conditions into this BRBPNN model, we were able to obtain detailed prediction curves for the absorption peaks. This method has the potential to help to reduce the experimental costs and improve the efficiency of investigating the properties of high-cost materials such as SWCNTs. [ABSTRACT FROM AUTHOR]

Organic semiconductors with very small optical energy gaps have attracted a lot of attention for near‐infrared‐active optoelectronic applications. Herein, we present a series of donor‐acceptor‐donor (D−A−D) organic semiconductors consisting of a highly electron‐deficient naphtho[1,2‐b:5,6‐b′]dithiophene‐2,7‐dione quinoidal acceptor and oligothiophene donors that show very small optical energy gaps of down to 0.72 eV in the solid state. Investigation of the physicochemical properties of the D−A−D molecules as well as theoretical calculations of their electronic structures revealed an efficient intramolecular interaction between the quinoidal acceptor and the aromatic oligothiophene donors in the D−A−D molecules; this significantly enhances the backbone resonance and thus reduces the bond length alternation along the π‐conjugated backbones. Despite the very small optical energy gaps, the D−A−D molecules have low‐lying frontier orbital energy levels that give rise to air‐stable ambipolar carrier transport properties with hole and electron mobilities of up to 0.026 and 0.043 cm2 V−1 s−1, respectively, in field‐effect transistors. [ABSTRACT FROM AUTHOR]

Semitransparent organic solar cells (STOSCs) are consisted of semitransparent active layer with a structure of both top and bottom transparent electrodes and can be used as power generation windows for both electricity generation and light transmission. In order to better realize these two functions, numerous attentions have been paid on the transparent top electrodes to acquire excellent transparency and maintain high conductivity, as well as the novel photoactive materials to achieve the absorption of near-infrared region. Herein, we review recent advances in a variety of transparent top electrodes and active materials for highly efficient STOSCs, moreover, we also further highlight the application of optical engineering in STOSCs, and give some thoughts about these STOSCs. [ABSTRACT FROM AUTHOR]

• This research investigates the enhanced near-infrared absorption of Cs 0.32 WO 3 nanoparticles for efficient interfacial solar steam generation. • Cs 0.32 WO 3 nanoparticles effectively converted solar energy into heat, resulting in efficient interfacial steam generation. • The synthetic nanoparticles were incorporated into a porous membrane, which showed a high evaporation rate of ∼ 3.15 kg·m−2·h−1 under one sun illumination. Solar steam generation has gained significant attention as a promising method for clean and sustainable water purification and desalination. The spectral absorption performance of the photothermal conversion material directly affects its thermal conversion efficiency. This research investigates the enhanced near-infrared absorption of Cs 0.32 WO 3 nanoparticles for efficient interfacial solar steam generation. In this study, Cs 0.32 WO 3 nanoparticles were synthesized using a simple co-precipitation and heat treatment method. The synthetic nanoparticles were then incorporated into a porous membrane to create a photothermal conversion material for solar steam generation and their near-infrared absorption properties were characterized. The experimental results demonstrated that the Cs 0.32 WO 3 nanoparticles effectively converted solar energy into heat, resulting in efficient interfacial steam generation. The membrane showed a high evaporation rate of of ∼ 3.15 kg·m−2·h−1 under one sun illumination. The findings of this study provide valuable insights into the design and development of efficient solar steam generation systems using near-infrared absorption nanomaterials. [ABSTRACT FROM AUTHOR]

Potassium- and rubidium-doped hexagonal tungsten bronzes (K- and Rb-HTBs) were examined in comparison with cesium-doped hexagonal tungsten bronze (Cs-HTB) for their crystal structure and dielectric functions via spectrophotometry, spectroscopic ellipsometry, X-ray diffraction, and X-ray photoelectron spectroscopy. A substantial amount of oxygen vacancy (V O) was detected in all HTBs via chemical analysis, which increased depending on the dopant K → Rb → Cs. A minute (201) peak appeared for K- and Rb-HTBs, indicating symmetry transition from P 6 3 / mcm to P 6 3 22 due to the pseudo Jahn–Teller distortion; this suggests that K- and Rb-HTBs contain lesser conduction electrons than Cs-HTB. Double-peaked loss functions were decomposed using the Drude−Lorentz theory, and the associated plasma frequency, polaron energies, and W5+ fractions increased as the dopants changed, K → Rb → Cs, with increasing V O content. The origin of the decreased V O content in K- and Rb-HTBs was discussed in relation to water-related defects on prismatic planes. Hexagonal tungsten bronzes were found to involve numerous oxygen vacancies (V O s), which produce both localized and delocalized electrons to trigger prominent near-infrared optical absorptions as well as destabilize the pseudo Jahn-Teller distortion. [Display omitted] • A substantial amount of oxygen vacancy (V O) was detected in alkali-doped hexagonal tungsten bronzes (HTBs). • V O content increased with the alkali kind as K.→ Rb → Cs. • Destabilization of pseudo Jahn-Teller distortion was observed in every HTB. • The plasma frequency, polaron energy, and W5+ fraction increased as K.→ Rb → Cs. • The origin of the decrease in V O could be related to the water-related defects on prismatic planes. [ABSTRACT FROM AUTHOR]

Two triphenylamines with thieno [3,2- b ] thiophene units were designed and synthesized. The radical cations obtained by the one-electron oxidation of these amines show a significant absorption in the near-infrared region. In particular, the derivative with three hexyl groups has excellent solubility, and its radical cation has a maximum absorption wavelength above 1400 nm. DFT calculations support these experimental results. A novel design strategy for NIR-II dyes is described. Two triphenylamines with thieno [3,2- b ] thiophene units were designed and synthesized. The radical cation with long-chain hexyl groups was stable in solution and showed a maximum absorption at 1430 nm. [Display omitted] • Novel triphenylamine with three thieno[3,2- b ]thiophenes. • The derivative with hexyl groups has excellent solubility. • The radical cation with hexyl groups was stable at room temperature in solution, and showed an absorption at 1430 nm. • Near-infrared absorbing dyes with high solubility and absorption in longer wavelength regions. [ABSTRACT FROM AUTHOR]

In this article, we focused on the interaction study of chemically fabricated PbS quantum dots (QDs) with model protein bovine serum albumin (BSA). The absorption of the PbS QDs has been observed in the NIR region at λ ≈ 1453 nm with a band gap ≈ 0.91 eV. The average size of the PbS QDs from the HRTEM study was found to be 3.5 nm with well crystalline nature and face-centered cubic (FCC) crystal phase as observed from the XRD study. The ground state complex formation between BSA and PbS QDs at room temperature has been observed and discussed from UV–VIS spectroscopy. The bioconjugate of PbS QDs-BSA formation has been occurring within a colony by the assembly of mesh formation as observed from the HRTEM images. The emission quenching of albumin in the presence of PbS QDs was occurring as observed from the emission spectrum. The energy transfer between serum protein and PbS QDs has been observed. The photo-current within the pure PbS QDs and PbS QDs-BSA conjugate was observed in the nA and µA range, respectively, under photo-conducting process. The albumin corona formation on the PbS QD was accounted for under the four temperatures (T = 300 K, 305 K, 311 K, 316 K) from the dynamic light scattering study. [ABSTRACT FROM AUTHOR]

Organic compounds with selective near‐infrared absorption and visible transparency are very desirable for fabrication of transparent/semitransparent optoelectronic devices. Herein, we develop a molecule with selective near‐infrared absorption property, QBNA‐O, in which four B←N units are incorporated to the core and two benzodioxin groups are introduced at the termini of the dibenzo‐azaacene skeleton. QBNA‐O exhibits a small optical gap of 1.39 eV due to the strong electron‐donating benzodioxin groups and the strong electron‐withdrawing B←N units. In toluene solution, QBNA‐O shows a strong absorption peak at 856 nm with the full width at half maximum (FWHM) of only 41 nm as well as very weak absorption in the visible range from 380 nm to 760 nm. Thin films of QBNA‐O exhibit the average visible transparency (AVT) of 78 % at the thickness of 205 nm and 90 % at the thickness of 45 nm. Solution‐processed organic field‐effect transistors (OFETs) of QBNA‐O display ambipolar transporting behavior with the electron mobility of 0.52 cm2 V−1 s−1 and the hole mobility of 0.013 cm2 V−1 s−1 together with excellent air‐stability. The selective NIR absorbing property and excellent charge transporting property imply that QBNA‐O can be used to fabricate transparent organic optoelectronic devices. [ABSTRACT FROM AUTHOR]

A series of near infrared absorption photothermal conversion polyurethane (PTPU) was synthesized with a cyanine dye to act as near infrared absorption component and polyethylene glycol 10,000 (PEG10000) to act as phase change material (PCM). The light resistant, pH dependence of dye and the effect of PEG10000 content on the properties of PTPU were investigated. The results showed that the cyanine dye had good light stability and was sensitive to pH, so a saturated solution of boric acid was added in the synthesis of PTPU to adjust its pH to 6 ~ 7. The crystalline degree of PTPU increased and its thermal stability decreased with the increasing of PEG10000 content; the light absorption of PTPU was mainly determined by the dye; the photothermal conversion efficiency and energy storage capability of PTPU increased with the increasing of PEG10000 and the PTPU can reach a higher temperature under illumination comparing to control polyurethane (PU); the PTPUs underwent a solid–solid phase change process and had excellent durability. [ABSTRACT FROM AUTHOR]

The present band‐selective photodetection is realized by incorporating different optical filters with broadband photodetectors (PDs). However, the use of the optical filters reduces the overall PD sensitivity. This work reports on the effort to develop high‐performance filter‐free band‐selective organic photodetectors (OPDs) having a heterostructure photoactive layer architecture, comprising a semiconducting shorter‐wavelength light depletion layer and a bulk heterojunction (BHJ) layer with an extended absorption to longer wavelengths. The filter‐free band‐selective photodetection is realized by adjusting the difference in wavelengths between the transmission cut‐off wavelength of the semiconducting light depletion layer and the absorption edge of the BHJ layer. For example, a filter‐free visible‐blind near‐infrared OPD, with a spectral rejection ratio of 100, a high responsivity of 0.39 A W−1, a high −3 dB cutoff frequency of 80 kHz, and a fast response time of ≈7 µs, is demonstrated, offering an exciting option for a plethora of applications in imaging and light communications. [ABSTRACT FROM AUTHOR]

Lead‐free halide double perovskites (A2BIBIIIX6) with attractive optical and electronic features are considered to be a promising candidate to overcome the toxicity and stability issues of lead halide perovskites (APbX3). However, their poor absorption profiles limit device performance. Here the absorption band edge of Cs2AgBiBr6 double perovskite to the near‐infrared range is significantly broadened by developing doped double perovskites, Cs2(Ag:Cu)BiBr6. The partial replacement of Ag ions by Cu ions in the crystal lattice is confirmed by the X‐ray photoelectron spectroscopy (XPS) and solid‐state nuclear magnetic resonance (ssNMR) measurements. Cu doping barely affects the bandgap of Cs2AgBiBr6; instead it introduces subbandgap states with strong absorption to the near‐infrared range. More interestingly, the near‐infrared absorption can generate band carriers upon excitation, as indicated by the photoconductivity measurement. This work sheds new light on the absorption modulation of halide double perovskites for future efficient optoelectronic devices. [ABSTRACT FROM AUTHOR]

Lead‐free halide double perovskites (A2BIBIIIX6) with attractive optical and electronic features are considered to be a promising candidate to overcome the toxicity and stability issues of lead halide perovskites (APbX3). However, their poor absorption profiles limit device performance. Here the absorption band edge of Cs2AgBiBr6 double perovskite to the near‐infrared range is significantly broadened by developing doped double perovskites, Cs2(Ag:Cu)BiBr6. The partial replacement of Ag ions by Cu ions in the crystal lattice is confirmed by the X‐ray photoelectron spectroscopy (XPS) and solid‐state nuclear magnetic resonance (ssNMR) measurements. Cu doping barely affects the bandgap of Cs2AgBiBr6; instead it introduces subbandgap states with strong absorption to the near‐infrared range. More interestingly, the near‐infrared absorption can generate band carriers upon excitation, as indicated by the photoconductivity measurement. This work sheds new light on the absorption modulation of halide double perovskites for future efficient optoelectronic devices. [ABSTRACT FROM AUTHOR]

The doped semiconductor nanocrystal with free holes in valence band exhibits strong near-infrared (NIR) local surface plasmon resonance effects, which is essential for photothermal agents. Herein, the hydrophilic Sb doped SnO2 nanocrystals were successfully prepared by a simple hydrothermal synthesis method. The doping makes the Sb doped SnO2 nanocrystals possessing defect structures. Compared with the un-doped SnO2 nanocrystals, Sb doped SnO2 nanocrystals exhibit stronger absorption in the NIR region from 500 to 1,100 nm and higher photothermal conversion efficiency (up to 73.6%) which makes the synthesized Sb doped SnO2 nanocrystals be used as excellent photothermal agents. Importantly, Sb doped SnO2 nanocrystals can efficiently kill cancer cells both in vitro and in vivo under the irradiation of a 980 nm laser with a power density of 0.6 W cm–2. In addition, Sb doped SnO2 nanocrystals can also be served as efficient CT imaging agents owing to the large X-ray attenuation coefficient of tin.

Two narrow band gap conjugated ternary copolymers comprising two electron-rich (donor, D) and one electron-deficient (acceptor, A) moieties regularly alternating along the polymer backbone were designed and synthesized. The polymers with the repeating unit in a D1-A-D2-A manner were constructed by copolymerizing a bisstannyled-D1 (D1 = n-alkyl-substituted cyclopentadithiophene) and a dibromo-monomer (Br-A-D2-A-Br, D2 = branched-alkyl-substituted cyclopentadithiophene, A =[1,2,5]selenadiazolo[3,4-c]pyridine or 5-fluorobenzo[c][1,2,5]selenadiazole) through a palladium-catalyzed Stille polymerization. This approach that enables variations in the donor fragment substituents can not only control the polymer regiochemistry but also the solubility. Two ternary copolymers exhibited absorbance up to near-infrared region along with relatively narrow band gap in the range of 1.02–1.26 eV. The polymeric photovoltaic cells based on CDTPSE/PC61BM show the short circuit density of 1.45 mA cm−2, open current voltage of 0.53 V, and photocurrent spectra response from 300 to 1,150 nm under AM 1.5 simulator (100 mW cm−2). It is indicated that it can be potentially applied to near infrared photodetectors.

Chloroaluminum phthalocyanine nanoparticles were successfully prepared by laser ablation in liquid, and the photoacoustic signal of the nanoparticles was measured. Chloroaluminum phthalocyanine powders were irradiated with nanosecond-pulsed laser (Nd:YAG, SHG) to prepare nanoparticles. The particle size of prepared nanoparticles decreased with the increase in laser fluence. Absorbance of prepared nanoparticles was increased with the increase in laser fluence. The ratio between two peaks would be changed because of crystal structure change by photothermal laser heating. The production yield from raw material powder to nanoparticle was 92.8% at a laser fluence of 300 mJ/cm2. The nanoparticle-dispersed solution was stable for 80 days. The photoacoustic signal intensity of prepared nanoparticles increased with the increase in laser fluence. [ABSTRACT FROM AUTHOR]