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This study delves into enhancing the efficiency and stability of perovskite solar cells (PSCs) by optimizing the surface morphologies and optoelectronic properties of the electron transport layer (ETL) using tungsten (W) doping in zinc oxide (ZnO). Through a unique green synthesis process and spin-coating technique, W-doped ZnO films were prepared, exhibiting improved electrical conductivity and reduced interface defects between the ETL and perovskite layers, thus facilitating efficient electron transfer at the interface. High-quality PSCs with superior ETL demonstrated a substantial 30% increase in power conversion efficiency (PCE) compared to those employing pristine ZnO ETL. These solar cells retained over 70% of their initial PCE after 4000 h of moisture exposure, surpassing reference PSCs by 50% PCE over this period. Advanced numerical multiphysics solvers, employing finite-difference time-domain (FDTD) and finite element method (FEM) techniques, were utilized to elucidate the underlying optoelectrical characteristics of the PSCs, with simulated results corroborating experimental findings. The study concludes with a thorough discussion on charge transport and recombination mechanisms, providing insights into the enhanced performance and stability achieved through W-doped ZnO ETL optimization.

Azide-oligo(ethylene glycol)-terminated self-assembled monolayers (N 3 -OEG-SAMs) are promising interfacial structures for surface functionalization. Its many potential applications include chemical/bio-sensing and construction of surface models owing to its cross-coupling activity that originates from the azide group and oligo(ethylene glycol) (OEG) units for non-specific adsorption resistance. However, there are only a few studies and limited information, particularly on the molecular-scale structures and local cross-coupling activities of N 3 -OEG-SAMs, which are vital to understanding its surface properties and interfacial molecular design. In this study, molecular-scale surface structures and cross-coupling activity of azide-hexa(ethylene glycol)-terminated SAMs (N 3 -EG 6 -SAMs) were investigated using frequency modulation atomic force microscopy (FM-AFM) in liquid. The N 3 -EG 6 -SAMs were prepared on Au(111) substrates through the self-assembly of 11-azido-hexa(ethylene glycol)-undecane-1-thiol (N 3 -EG 6 -C 11 -HS) molecules obtained from a liquid phase. Subnanometer-resolution surface structures were visualized in an aqueous solution using a laboratory-built FM-AFM instrument. The results show a well-ordered molecular arrangement in the N 3 -EG 6 -SAM and its clean surfaces originating from the adsorption resistance property of the terminal EG 6 units. Surface functionalization by the cross-coupling reaction of copper(I)-catalyzed azide-alkyne cycloaddition was observed, indicating a structural change in the form of fluctuating structures and island-shaped structures depending on the concentration of the alkyne molecules. The FM-AFM imaging enabled to provide information on the relationship between the surface structures and cross-coupling activity. These findings provide molecular-scale information on the functionalization of the N 3 -EG 6 -SAMs, which is helpful for the interfacial molecular design based on alkanethiol SAMs in many applications.

In this study, the spontaneous microstructure tuning of TiO 2 was observed by aging the ethanol/water TiO 2 paste for up to 20 days at ambient conditions. A dynamic light scattering study reveals that it formed the outstanding reproducible TiO 2 microstructure with a ∼200 nm average particle size and stabilizes in 6 to 20 days under an ambient atmosphere. Interestingly, the as-deposited day 15 sample spontaneously changed its crystallinity upon keeping the paste at ambient conditions; meanwhile the day 0 sample showed an amorphous structure. A dense, uniform, and stable TiO 2 electrode was cast on a fluorine doped-tin oxide substrate using the electrospray technique. We exploit the spontaneous evolution of the TiO 2 nanopowder to revisit the fabrication procedure of the TiO 2 photoelectrode for dye-sensitized solar cells (DSSCs). The controlled microstructure TiO 2 film was used in DSSCs, which, to the best of our knowledge, achieved the highest power conversion efficiency of 9.65% using N719 dye in sensitizing the TiO 2 photoanode.

With the rapid improvement of perovskite solar cells (PSCs), long-life operational stability has become a major requirement for their commercialization. In this work, we devised a pristine cesium-formamidinium-methylammonium (termed as CsFAMA) triple-cation-based perovskite precursor solution into the ionic liquid (IL)-assisted MAPbI 3 nanoparticles (NPs) through a seeded growth approach in which the host IL-assisted MAPbI 3 NPs remarkably promote high-quality perovskite films with large single-crystal domains, enhancing the device performance and stability. The power conversion efficiency (PCE) of the MAPbI 3 NP-seeded growth of MAPbI 3 NPs/CsFAMA-based PSCs is as high as 19.44%, which is superior to those of MAPbI 3 NPs and pristine CsFAMA films as the photoactive layer (9.52 and 17.33%, respectively). The long-term light-soaking and moisture stability of IL-aided MAPbI 3 NPs/CsFAMA-based devices (non-encapsulated) remain above 90 and 80%, respectively, of their initial output after 2 h of light illumination (1 sun) and 6000 h storage at ambient with a relative humidity range of 30-40%. The use of the IL-assisted MAPbI 3 NP-seeded growth for PSCs is a significant step toward developing stable and reliable perovskite photovoltaic devices.

Nicotinic acetylcholine (nACh) receptors are pentameric ligand-gated ion channels that mediate fast synaptic transmission. The α4β2 nACh receptor is highly expressed in the brain and exists in two functional stoichiometries: the (α4) 2 (β2) 3 and (α4) 3 (β2) 2 that differ by an ACh-binding site at the α4-α4 interface of (α4) 3 (β2) 2 receptors. Methyllycaconitine (MLA) is an nACh receptor antagonist, and while potent at both α7 and α4β2 nACh receptors, it has a higher selectivity for the α7 nACh receptor. The anthranilate-succinimide ester side-chain is important for its activity and selectivity. Here we identify a simplified MLA analogue that contains only the A and E ring skeleton of MLA, AE succinimide, that binds close to the channel lumen to display insurmountable inhibition at α4β2 nACh receptors. Although inhibition by AE succinimide was found to be voltage-dependent indicating a possible pore channel blocker, substituted-cysteine accessibility experiments indicated it did not bind between 2'-16' region of the channel pore. Instead, we found that upon binding and in the presence of ACh, there is a conformational change to the channel membrane that was identified when the compound was assessed against (α4 V13'C)β2 nACh receptors. It was found that in the 3:2 stoichiometry the two adjacent α4 subunits containing 13' cysteine mutations formed a disulfide bond and occluded ion conductance. This was reversed by treatment with the reducing agent, dithiothreitol. Thus, AE succinimide has a different mechanism of inhibition to both MLA and other AE analogues, such as AE bicyclic alcohol, in that upon binding to an as yet unidentified site, AE succinimide in the presence of ACh induces a conformational change to the channel that generates a ligand-bound closed state.

Living systems achieve sophisticated functions using supramolecular protein assemblies, in which the protein building blocks possess a specific secondary structure and are noncovalently arranged in a preprogrammed manner. Herein, we demonstrate the one-step synthesis of one-dimensional macromolecular assemblies by simply mixing a glycine-based isocyanide with a nickel catalyst, in which helical constituent polymers are linked end-to-end through multiple hydrogen bonds. The applicable scope of this approach is not confined to a particular monomer bearing a specially designed pendant, but covers a wide range of glycine-based isocyanides with or without aromatic and other functional groups. Surprisingly, copolymerization with an analogous chiral isocyanide (1 mol %) afforded an almost perfect one-handed helical supramolecular fiber owing to intramolecular/intermolecular dual chiral amplifications. The simplicity and broad applicability of this approach, which can also afford exquisite chiral amplification, enable the creation of a wide variety of functional supramolecular assemblies and provide access to new supramolecular materials.

In the design of electron-transport layers (ETLs) to enhance the efficiency of planar perovskite solar cells (PSCs), facile electron extraction and transport are important features. Here, we consider the effects of different titanium oxide (TiO 2 ) polymorphs, anatase and brookite. We design and fabricate high-phase-purity, single-crystalline, highly conductive, and low-temperature (<180 °C)-processed brookite-based TiO 2 heterophase junctions on fluorine-doped tin oxide (FTO) as the substrate. We test and compare single-phase anatase (A) and brookite (B) and heterophase anatase-brookite (AB) and brookite-anatase (BA) as ETLs in PSCs. The power-conversion efficiencies (PCEs) of PSCs with low-temperature-processed single-layer FTO-B as the ETL were as high as 14.92%, which is the highest reported efficiency of FTO-B-based single-layer PSC. This implies that FTO-B serves as an active phase and can be a potential candidate as an n-type ETL scaffold in planar PSCs. Moreover, the surface of highly crystalline brookite TiO 2 exhibits a tendency toward interparticle necking, leading to the formation of compact scaffolds. Furthermore, PSCs with heterophase junction FTO-AB ETLs exhibited PCEs as high as 16.82%, which is superior to those of PSCs with single-phase anatase (FTO-A) and brookite (FTO-B) as the ETLs (13.86% and 14.92%, respectively). In addition, the PSCs with FTO-AB exhibited improved efficiency and decreased hysteresis compared with those with FTO-BA (13.45%) due to the suitable band alignment with the perovskite layer, which resulted in superior photogenerated charge-carrier extraction and reduced charge accumulation at the interface between the heterophase junction and perovskite. Thus, the present work presents an effective strategy by which to develop heterophase junction ETLs and manipulate the interfacial energy band to further improve the performance of planar PSCs and enable the clean and eco-friendly fabrication of low-cost mass production.

The molecular orientation of organic molecules of zinc phthalocyanine (ZnPc) in single-component films on copper iodide (CuI) substrates can be controlled to achieve a molecular orientation lying flat on the substrate (flat-on) owing to π-d orbital interactions between the ZnPc molecules and the CuI. A 3-fold enhancement in the performance of organic photovoltaic cells has been reported by introducing a CuI interlayer between a ZnPc:fullerene (C60) bulk heterojunction (BHJ) film and the substrate. However, the mechanism underpinning the resultant solar cell performance enhancement was unclear. Herein, we report on the results of using in situ reflection absorption spectroscopy measurements during the vacuum deposition of coevaporated ZnPc:C60 BHJ films on various substrates to investigate the ZnPc molecular orientation. Our results revealed that the flat-on molecular orientation of ZnPc molecules in ZnPc:C60 BHJ films on CuI interlayers and flat-on ZnPc substrates can be successfully identified via the strong π-π interactions between the BHJ film and the substrate. The π-π interactions between individual ZnPc molecules are stronger than the π-d interactions between ZnPc molecules and CuI in coevaporated ZnPc:C60 films, as is evident from the molecular orientation of ZnPc, as determined by in situ reflection absorption spectroscopy. Our findings demonstrate that precisely controlling the molecular orientations of the films could enhance organic photovoltaic (OPV) performance. The present work provides important insights that will enable the design of higher performance OPV cells., Competing Interests: The authors declare no competing financial interest.

Vacuum deposition is a simple and controllable approach that aims to form higher-quality perovskite films compared with those formed using solution-based deposition processes. Herein, we demonstrate a novel method to promote the intercalation control of inorganic cesium lead iodide (CsPbI 3 ) perovskite thin films via alternate vacuum deposition. We also investigated the effect of layer-by-layer deposition of PbI 2 /CsI to fabricate efficient planar heterojunction CsPbI 3 thin films and solar cells. This procedure is comparatively simple when compared with commonly used coevaporation techniques; further, precise intercalation control of the CsPbI 3 thin films can be achieved by increasing the number of layers in the layer-by-layer deposition of PbI 2 /CsI. The best control and the highest reproducibility were achieved for the deposition of four double layers owing to the precise intercalation control during the deposition of the CsPbI 3 thin film. A power conversion efficiency of 6.79% was obtained via alternating vacuum deposition of two double layers with a short-circuit current density ( J sc ) of 12.06 mA/cm 2 , an open-circuit voltage ( V oc ) of 0.79 V, and a fill factor (FF) of 0.72. Our results suggest a route for inorganic precursors to be used for efficient perovskite solar cells via alternating vacuum deposition., Competing Interests: The authors declare no competing financial interest.

In this study, we present novel insights into the light-soaking effect of inverted polymer solar cells (PSCs), where the open-circuit voltage ( V oc ) of the cells improves over time under light irradiation. The effect was investigated by electron spin resonance (ESR) studies of bare indium tin oxide (ITO) and piperazine derivative-modified ITO/regioregular poly(3-hexylthiophene) (P3HT):[6,6]-phenyl C 61 butyric acid methyl ester (PCBM) substrates. These results were combined with alternating current impedance spectroscopy (IS) measurements of inverted PSCs based on the above substrates. In ESR experiments with the substrates under white light irradiation, with a UV light component, many P3HT •+ radical cations were observed in the bare-ITO/P3HT:PCBM substrate. The number of radical cations was considerably suppressed in the ITO/P3HT:PCBM substrates with ITO modified by piperazine derivatives. This is because adsorbed oxygen molecules on the ITO acted as acceptor dopants for photoexcited P3HT, and the amount of adsorbed oxygen was decreased by modifying the ITO with piperazine derivatives. In IS measurements of the inverted PSCs under white light irradiation, a decrease in the electric capacitance (CPE2) of an electric double layer formed at the ITO/P3HT:PCBM interface was observed. A strong correlation was observed between the decrease of CPE2 and the increase of V oc . From these results, the light-soaking behavior was attributed to the removal of an electron injection barrier formed between ITO and PCBM, under white light irradiation., Competing Interests: The authors declare no competing financial interest.

We report a simple method to achieve efficient nanostructured organic photovoltaics via patterning copper iodide (CuI) nanocrystals on indium tin oxide by glancing angle deposition. The strong interfacial interaction between zinc phthalocyanine (ZnPc) and CuI leads to the formation of nanopillar arrays with lying-down molecular order, which greatly improve light absorption and surface roughness for exciton dissociation. Optimized ZnPc/C(60) bilayer cell has a power conversion efficiency of 4.0 ± 0.1%, which is about 3-fold larger than that of conventional planar cell.