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We summarize various effective methods for controlling the film thickness and structural phases in 2D/3D perovskite heterojunction structures and discuss possible solutions to improve the performance of perovskite devices.

This review critically analyses the chemical design and functionality of phthalocyanines in perovskite solar cells, which are generally applied in the perovskite layer, as the hole transport layer, or as an interlayer.

Lewis acid–base passivation is a significant technique to achieve structural stability of perovskite solar cells (PSCs) by overcoming the issues of wide grain boundaries, crystal defects, and the instability of PSCs. In this work, the combined effects of thiophene with phthalocyanine (Pc) as isomers (S2 and S3) on the photovoltaic performance of PSCs were studied for the first time. Through density functional theory calculations, we confirmed that the position of the S atom in the structure affects Lewis acid–base interactions with under-coordinated Pb2+ sites. The morphology of methylammonium lead iodide (MAPbI3) for passivated devices was improved and thin dense layers with compact surface and large grain size were observed, leading to improvement of the charge extraction ability and reduction of non-radiative recombination and the trap density. A highest power conversion efficiency of 18% was achieved for the Pc S3 passivated device, which was 6.69% more than that of the controlled device. Furthermore, the Pcs passivated devices demonstrated remarkable stability under high-moisture and high-temperature conditions.

Chiral organometallic complexes have demonstrated many potential and practical applications. However, building metal-induced chirality for square-planar complexes still remains a big challenge, because their 2D planar molecular structures are usually superimposable on their mirror images. Herein, we report a straightforward and efficient way to achieve a novel kind of planar chirality by constructing 3D double-layer molecular structures. When the achiral ligand 1,3,4-oxadiazole-2-thiol (OXT) was used to bridge two square-planar complexes, a pair of racemic

Inorganic hole transporting materials (HTMs), particularly NiOX, have shown significant promise in boosting the efficiency and stability of perovskite solar cells. However, a major challenge facing NiOX-based p-i-n perovskite solar cells (PSCs) is their direct contact with the absorber layer, which can lead to photovoltage and filling factor losses. Additionally, under-coordinated Ni cations can react with the perovskite and cause damage. In this work, we address these issues by using an ionic compound (QAPyBF4) as a perovskite additive to passivate the entire perovskite layer and interact with under-coordinated Ni cations. Our results show that the introduction of QAPyBF4 significantly enhances the performance and stability of NiOX-based PSCs. Specifically, the decorated cells achieved a power conversion efficiency (PCE) of 23.38% and a fill factor (FF) of 85.46%, with no need for complicated surface treatment or NiOX doping. The QAPyBF4 compound passivates the buried NiOX/perovskite interface, effectively reducing photovoltage and filling factor losses. Moreover, the [BF4]‒ component of the compound interacts with under-coordinated Ni cations to prevent their negative impact on the perovskite layer. Overall, our study proposes a simple and effective approach to optimize the performance and stability of NiOX-based PSCs through the use of ionic compound additives. Our findings suggest that addressing buried NiOX/perovskite interface issues and under-coordinated Ni cation considerations are critical in achieving high-performance and stable NiOX-based PSCs.

Perovskite solar cells (PSCs) have grabbed much attention of researchers owing to their quick rise in power conversion efficiency (PCE). However, long-term stability remains a hurdle in commercialization, partly due to the inclusion of necessary hygroscopic dopants in hole transporting materials, enhancing the complexity and total cost. Generally, the efforts in designing dopant-free hole transporting materials (HTMs) are devoted toward small molecule and polymeric HTMs, where small molecule based HTMs (SM-HTMs) are dominant due to their reproducibility, facile synthesis, and low cost. Still, the state-of-art dopant-free SM-HTM has not been achieved yet, mainly because of the knowledge gap between device engineering and molecular designs. From a molecular engineering perspective, this article reviews dopant-free SM-HTMs for PSCs, outlining analyses of chemical structures with promising properties toward achieving effective, low-cost, and scalable materials for devices with higher stability. Finally, an outlook of dopant-free SM-HTMs toward commercial application and insight into the development of long-term stability PSCs devices is provided.

Acceleration of singlet-triplet intersystem crossings (ISC) is instrumental in bolstering triplet exciton harvesting of multi-resonance thermally activated delayed fluorescent (MR-TADF) emitters. This work describes a simple gold(I) coordination strategy to enhance the spin-orbit coupling of green and blue BN(O)-based MR-TADF emitters, which results in a notable increase in rate constants of the spectroscopically observed ISC process to 3×10

Ultralong room-temperature phosphorescence (RTP) is greatly important in a series of applications, but obtaining RTP from metal-free organic materials is still an enormous challenge due to the spin-forbidden nature of triplet excitons. Because of its electron-rich nature and easy derivatization, carbazole (Cz) is widely used to build organic RTP and thermally activated delayed fluorescence (TADF) materials. However, Liu et al. (

Layered double hydroxide (LDH) materials, especially metal–organic framework (MOF)-derived LDHs, have attracted much attention in electrochemical capacitor applications. However, the construction o...

Three novel aggregation induced emission (AIE) active molecules TriPE-PA, TriPE-α-NA and TriPE-β-NA were designed and successfully synthesized through a simple synthetic route. The position 9 of chromophore anthracene was introduced with the phenyl, 1-naphthyl and 2-naphthyl group, respectively, and afterwards the triphenylethylene was embedded as an AIE active group at position 10, thus generating two kinds of stable asymmetric configurations in the latter two compounds. These materials display sky-blue emission and typical AIE characteristics, among which TriPE-PA presents the best AIE phenomenon with an αAIE value (ΦF(Film)/ΦF(THF)) of 63. Subsequent studies show that they exhibit very similar photophysical and electrochemical properties. However, it was observed that the TriPE-α-NA and TriPE-β-NA performances were much superior to TriPE-PA when they all functioned as the non-doped emitting layers in OLEDs, among which TriPE-β-NA presented an over six times higher EQE value in comparison to TriPE-PA. This probably resulted from the support of double stable asymmetric configurations in TriPE-α-NA and TriPE-β-NA, which gives them a better membrane morphology and thermodynamic stability. The theories of energy traps at grain boundaries were employed to explain such a causal relationship. Such results reemphasize a neglected strategy which may be helpful for the design of new AIE materials with high stability of efficiency.

Perovskite solar cells (PSCs), one of the most promising photovoltaic technologies, have been widely studied due to their high power conversion efficiency (PCE), low cost, and solution processability. The architecture of PSCs determines that high PCE and stability are highly dependent on each layer and the related interface, where nonradiative recombination occurs. Conventional synthetic chemical materials as modifiers have disadvantages of being toxic and costly. Natural molecules with advantages of low cost, biocompatibility, and being eco-friendly, and have improved PCE and stability by modifying both functional layers and interface. In this review, we discuss the roles of natural molecules on PSCs devices in terms of the perovskite active layer, interface, carrier transport layers (CTLs), and substrate. Finally, the summary and outlook for the future development of natural molecule-modified PSCs are also addressed.

Defects and energy offsets at the bulk and heterojunction interfaces of perovskite are detrimental to the efficiency and stability of perovskite solar cells (PSCs). Herein, we designed an amphiphilic π-conjugated ionic compound (QAPyBF

A new series of axially chiral binuclear Pt(II) complexes with bridging ligands of binaphthalenes and octahydro-binaphthalenes and auxiliary ligands of β-diketones were designed and prepared. These complexes, identified by spectral and electrochemical methods and single-crystal X-ray diffraction, emit an orange-red phosphorescence with a quantum yield up to 21% and 70% in solution and solid, respectively, due to the effect of steric hindrance from bridging ligands and the 2,3-position extension of chiral axis planes. They can be used as emitters in solution-processed organic light-emitting diodes to achieve luminance efficiency, asymmetry factor, and external quantum efficiency up to 5.4 cd A-1, 3.0 × 10-3, and 3.1%, respectively. Moreover, the essential relationships between their chemical structures and luminescence quantum efficiency and asymmetry factor are discussed, which affords explicit insights for designing circularly polarized luminescent materials and devices.

In this study, a nanocomposite based on graphene oxide (GO) and non-peripheral octamethyl-substituted copper(II) phthalocyanine (N-CuMe2Pc) nanorod as photosensitizer, was synthesized and characterized by X-ray diffraction, transmission electron microscopy (TEM), scanning electron microscopy (SEM), UV–vis diffuse reflectance spectroscopy, FTIR and Raman spectroscopy. For the first time, the photocatalytic activity of GO/Pc nanocomposite was tested for the reduction of aqueous chromium (VI) (10 mg/L) as a model pollutant, and the results were compared with those of pure N-CuMe2Pc and GO. Visible light was used as source and Cr(VI) concentration was monitored during 120 min of treatment period. Up to 95% photocatalytic reduction of toxic Cr(VI) ions confirms that GO/Pc nanocomposite photocatalyst is clearly effective for wastewater treatment. Meanwhile, neat GO and N-CuMe2Pc nanorod were able to reduce only less than 10% of initial Cr(VI) ions. The reusability of the developed photocatalyst was also investigated. The retained amount of Cr(VI) increased from 2% at first cycle to around 17% at third cycle, due to loss of photocatalyst during collection process and morphology changes from nanorods to nanoparticles. Our results demonstrate the remarkably improved photocatalytic performance of GO/Pc nanocomposite for the practical application in wastewater remediation.

This work involves the preparation and characterization of poly(styrene-b-isoprene-b-styrene)-poly(dimethylsiloxane-co-methylhydrosiloxane) (SIS-c-PDMS-co-PMHS) crosslinked membranes towards CH4/N2 separation. SIS-c-PDMS-co-PMHS was synthesized via a simple hydrosilylation reaction with various PDMS-co-PMHS contents. The structure of crosslinked membranes was investigated by Fourier transform infrared spectroscopy, indicating the degree of hydrosilylation reaction. The morphology of sample membranes was observed in detail by means of Scanning Electron Microscope analysis. Thermodynamic stability and the crosslinked behavior of crosslinked membranes were explored by thermogravimetric analysis and Soxhlet extraction experiments. Furthermore, single gas (CH4, N2) permeability was measured using the time-lag method. The CH4 permeability of crosslinked membranes with 70 wt% PDMS-co-PMHS could reach 503 Barrer at 25 °C and 1 bar, which is significantly greater than that of SIS (25.9 Barrer), while the CH4/N2 ideal selectivity hardly changed. Notably, CH4 permeability further improved by 77.6% (893.4 Barrer) as the temperature increased to 55 °C. For the CH4/N2 (50/50 vol%) mixed gas, the SIS-c-PDMS-co-PMHS-70 sample membrane exhibited ideal gas separation performance relative to that of the pure SIS membrane (CH4: 447.4 vs. 24.2 Barrer，N2: 188.1 vs. 9.46 Barrer).

A tetra-dentate ligand L [3,3′-((pyridin-2-ylmethyl)azanediyl)dipropanamide] was synthesized and characterized by spectroscopic and structural methods. The reaction of L with two different copper(II) halides [CuX2; X = Br, Cl] in a similar condition yielded two different compounds of [LCuCl]Cl, 1 and [CuLBr]2[CuBr4]·CH3OH·H2O, 2. Both compounds were characterized by several physicochemical techniques. Single-crystal X-ray studies revealed that the Cu(II) centers in the cationic complexes 1 and 2 are in a square pyramidal N2O2X (X = Cl and Br) environment. Compound 1 is chromotropic and its solvatochromism and halochromism properties were investigated. It was found that the observed positive solvatochromism is due to structural change and solvation of the vacant site of the complex. The complex demonstrated distinct reversible spectral change over the pH range 1.3–12.1 and can act as pH-induced off–on–off absorption switch through deprotonation and the Cu–O to Cu–N bond rearrangement of the coordinated amide groups in aqueous solution.

Owing to their excellent thermal and chemical stability properties, low cost, and easy purification processes, metal phthalocyanines have received extensive research attention. To reveal the influence of alkyl-chain length of substituents on phthalocyanines rings, we prepared three small organic molecules based on copper phthalocyanine rings substituted with end-capping ethyl, butyl, and hexyl, alkyl groups. The molecular orientation and intermolecular π-π stacking of these materials were affected by the alkyl chains, resulting in different hole mobilities. The crystallization of the phthalocyanines improved as the carbon chain length was extended, which we attributed to increased intermolecular π-π stacking. We used density functional theory calculations and solution cyclic voltammetry and ionization potential measurements to confirm a small difference in the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels. The morphology, molecular orientation and π-stacking were affected by the introduction of alkyl chains and resulted in differences in the photovoltaic performance of solution processed PSC based on these copper phthalocyanines. The long-term stability of devices based on CuEtPc, CuBuPc, and CuHePc was improved by elongating the carbon chains because of the better hydrophobicity of the phthalocyanines.

Recently, flexible organic field-effect transistor (OFET)-based pressure sensors have been attracting significant interest for promising applications in electronic skin (e-skin) and wearable health...

Recent progress in the construction of non-peripheral octamethyl-substituted copper(II) phthalocyanine (N-CuMe2Pc) has opened up new strategies for energy storage applications. Since metal phthalocyanines can deliver excellent redox activities, we have prepared composite based on different ratios of N-CuMe2Pc and graphene oxide (GO) through a simple ultrasound process and evaluated their electrochemical performance for supercapacitor applications. As-prepared composites exhibit superior electrochemical activities as the results of the synergistic effect. A maximum specific capacitance of 291.6 F g−1 is achieved for the G10P2 electrode (Graphene oxide 10 mg and N-CuMe2Pc 2 mg) at 0.5 A g−1 which two times higher than their individual components. Further, the fabricated symmetric device shows that the excellent cyclic stability of about 100.1% over 5000 cycles. The experimental findings ensure the potential application of copper-phthalocyanine/GO composite as an electrode material for the next-generation supercapacitor applications.

The amorphous/nanocrystal hybrid TiO2 based butterfly wing structure (ANH-TiO2-BW) is successfully fabricated via an easily controlled self-deposition sintering method. The hybrid configuration greatly enhances the structural toughness and maintains the original morphology throughout the experiment. The ANH-TiO2-BW configuration is very conductive to gas diffusion, and the calculated value of the diffusion coefficient (Dk) is 0.37 cm2 s−1 at room temperature (27 °C). As the completely reserved structure provides sufficient effective gas diffusion channels and gas molecule reaction sites, the ANH-TiO2-BW based gas sensor demonstrates a remarkable sensitivity to acetone, up to 1.88 at a detection limit of 5 ppm at room temperature and 180.08 for 200 ppm at an optimal operating temperature of 65 °C. Meanwhile, the device exhibits long-term stability, good cycle-to-cycle repeatability and selectivity to trace acetone at room temperature. Moreover, benefiting from the 3D penetrating porous structure, the average response time of the device is only about 1.8 s. This work may open up a new way for the design and application of toxic and harmful gas detection at room temperature.

Graphene quantum dots (GQDs) have received much attention in biosensor applications due to their unique properties. In this work, we demonstrate the introduction of GQDs into cobalt phthalocyanine (CoPc) for simultaneous electrochemical Dopamine (DA) and Uric acid (UA) detections. The GQDs with size of less than 10 nm were decorated onto the CoPc, and the modified electrode exhibited superior sensing performance towards DA and UA. The fabricated sensor showed a detection limit of 18 and 145 nM for DA and UA, respectively. Besides, the sensor displayed a wide linear range with excellent reproducibility and repeatability characteristics.

After discovering graphene, the two-dimensional materials have gained considerable interest in the electrochemical applications, especially in energy conversion, storage, and bio-sensors. Siloxene, a novel two-dimensional low-buckled structure of Si networks with unique properties, has received the researcher’s attention for a wide range of applications. Though the electronic and optical properties of siloxene have been explored in detail previously, there is a lack of electrochemistry studies of siloxene as the result of material degradation, and the investigation is still open-ended to enhance the electrochemical application. Recently, siloxene has been used for supercapacitor, lithium-ion batteries, and dopamine bio-marker detections. This chapter highlights the recent development of siloxene synthesis and its electrochemical properties in energy and sensor applications. The plannar Si structure with Si6 rings interconnected with different oxygen, hydroxyl functional groups, and large interlayer spacing of siloxene sheets can promote the active sites for enhanced electrochemical performance. This chapter provides the current state-of-the-art in the field and a perspective for future development in the electrochemistry field of siloxene.

Memristive devices and systems have emerged as powerful technologies to fuel neuromorphic chips. However, the traditional two-terminal memristor still suffers from nonideal device characteristics, raising challenges for its further application in versatile biomimetic emulation for neuromorphic computing owing to insufficient control of filament forming for filamentary-type cells and a transport barrier for interfacial switching cells. Here, we propose three-terminal memristors with a top-gate field-effect geometry by employing a ferroelectric material, poly(vinylidene fluoride–trifluoroethylene), as the dielectric layer. This approach can finely modulate ion transport and contact barrier at the switching interface in non-filamentary perovskite memristors, thus, creating two distinct operation modes (volatile and nonvolatile). Additionally, perovskite memristors show desirable resistive switching performance, including forming-free operation, high yield of 88.9%, cycle-to-cycle variation of 7.8%, and low operating current of sub-100 nA. The dual-mode memristor is capable of emulating biological nociception in both active (perceiving pain) and blocked states (suppressing pain signaling).

Metal-organic framework derivatives are potential candidates for supercapacitors electrodes because of their controllable structure and high surface area. In this study, we report, for the first time, the in-situ conversion of NiCe-LDH from Ni-MOF at different synthesis time and its electrochemical activities towards asymmetric supercapacitor. The flower-like NiCe-LDHs provide extra active sites for redox reactions and achieved a maximum specific capacitance of 1500.6 F g-1 for NiCe-LDH/10 electrode as a result of higher surface area and rich redox chemistry. The fabricated asymmetric supercapacitor device exhibited a maximum energy density of 13.86 Wh kg-1 with superior cyclic stability. This work proves the potential of MOF derived LDH materials for electrochemical supercapacitor applications.

Copper(II) phthalocyanine (CuPc) and non-peripheral octamethyl-substituted copper(II) phthalocyanine (N-CuMe2Pc) were combined with reduced graphene oxide (rGO) via a precipitation method to form CuPc/rGO and N-CuMe2Pc/rGO nanocomposites, respectively. CuPc nanorods are distributed on rGO, and N-CuMe2Pc exists as nanorods and nanoparticles on rGO. The Cr(VI) removal ratio of N-CuMe2Pc/rGO exposed in simulated sunlight is 99.0% with a fast photocatalytic reaction rate of 0.0320 min−1, which is approximately 1.5 times faster than that of CuPc/rGO (0.0215 min−1) and far surpasses that of pristine phthalocyanine and rGO. As an electron acceptor, rGO can suppress the recombination of photo-induced electron-hole pairs and also can provide a large surface area for Cr(VI) removal, both of which are beneficial to the reducing capacity of the nanocomposites. The higher removal efficiency of N-CuMe2Pc/rGO compared with that of CuPc/rGO is attributed to the higher specific surface area, higher light harvesting, higher conductivity and more negative lowest unoccupied molecular orbital level of N-CuMe2Pc/rGO. The N-CuMe2Pc/rGO nanocomposite shows excellent photochemical recyclability which is essential for application in wastewater treatment.

Graphene-based composites are widely used in the photocatalytic treatment of heavy-metal ions or dyes. In this study, we developed a facile in situ precipitation method for preparing a non-peripheral octamethyl-substituted cobalt(II)phthalocyanine (N-CoMe

Artificial limbs have been widely investigated in the past several decades, and multifuncional bionic limbs have already been constructed. However, due the lack of nociceptive systems, amputees still cannot feel ubiquitous noxious stimuli through bionic limbs. The construction of artificial nociceptors can bring bionic limbs closer to real flesh and bone. In daily life, UV irradiation is an invisible potential noxious stimulus to human skin and eyes. Furthermore, it is well known that the synthetic polymers widely used in bionic limbs can be degraded by UV radiation, accelerating their aging. Based on the above, UV damage-sensing nociceptors could be a feasible strategy to solve these existing problems. Here, azobenzene-functionalized gold nanoparticles (Azo-Au NPs) are embedded in insulating poly(methyl methacrylate) (PMMA) to construct a two-terminal memristor. With UV irradiation as a light damage medium, major nociceptive behaviors such as "threshold", "relaxation" and "sensitization" are successfully emulated, demonstrating its potential application as a nociceptive system.