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Abstract Atomically precise gold clusters are highly desirable due to their well‐defined structure which allows the study of structure–property relationships. In addition, they have potential in technological applications such as nanoscale catalysis. The structural, chemical, electronic, and optical properties of ligated gold clusters are strongly defined by the metal–ligand interaction and type of ligands. This critical feature renders gold–phosphine clusters unique and distinct from other ligand‐protected gold clusters. The use of multidentate phosphines enables preparation of varying core sizes and exotic structures beyond regular polyhedrons. Weak gold–phosphorous (Au–P) bonding is advantageous for ligand exchange and removal for specific applications, such as catalysis, without agglomeration. The aim of this review is to provide a unified view of gold–phosphine clusters and to present an in‐depth discussion on recent advances and key developments for these clusters. This review features the unique chemistry, structural, electronic, and optical properties of gold–phosphine clusters. Advanced characterization techniques, including synchrotron‐based spectroscopy, have unraveled substantial effects of Au–P interaction on the composition‐, structure‐, and size‐dependent properties. State‐of‐the‐art theoretical calculations that reveal insights into experimental findings are also discussed. Finally, a discussion of the application of gold–phosphine clusters in catalysis is presented.

Though reducing non-emissive triplet excited-states using quenchers effectively improves organic semiconductor laser diode (OSLD) performance, existing quenchers are not suitable for devices. Here, the authors designed a solid-state triplet quencher for OSLD under optical and electrical excitation.

Abstract In polymer‐based organic photovoltaic cells, the capability of charge extraction/injection of molybdenum trioxide (MoO3) is demonstrated as interface layer for polymer bulk heterojunction (BHJ). The present work determines the dipole formed at the MoO3 and conjugated poly [2,3‐bis (3‐octyloxyphenyl) quinoxaline‐5,8‐diyl‐alt‐thiophene‐2,5‐diyl] (TQ1):(6,6)‐Phenyl C71 butyric acid methyl ester (PC71BM) bulk heterojunction interface. This dipole has a major influence on the charge transport across the TQ1:PC71BM interface. The formation of the dipole is determined with electron spectroscopy and the depth profiling technique neutral impact collision ion scattering spectroscopy. Metastable induced electron and UV‐photoelectron spectroscopy is applied to determine the enclosed surface coverage of minimum 1.5 nm MoO3 and a maximized dipole strength of 2.4 eV with >2 nm MoO3 deposition on BHJ. It is also demonstrated that the air exposure reduces the dipole at the interface and leads to a decrease in cell performance providing evidence that the dipole formed at the interface is beneficial for the functioning of photovoltaic cells. The results indicate that the reduction in dipole might not be the only mechanism leading to cell performance degradation. The findings of the present work have relevance for other BHJ systems because MoO3 as high work function material is likely to interact with other organic materials in a similar way.

Radio frequency (RF) magnetron sputtering allows the fabrication of TiO2 films with high purity, reliable control of film thickness, and uniform morphology. In the present study, the change in surface roughness upon heating two different thicknesses of RF sputter-deposited TiO2 films was investigated. As a measure of the process of the change in surface morphology, chemically -synthesised phosphine-protected Au9 clusters covered by a photodeposited CrOx layer were used as a probe. Subsequent to the deposition of the Au9 clusters and the CrOx layer, samples were heated to 200 ℃ to remove the triphenylphosphine ligands from the Au9 cluster. After heating, the thick TiO2 film was found to be mobile, in contrast to the thin TiO2 film. The influence of the mobility of the TiO2 films on the Au9 clusters was investigated with X-ray photoelectron spectroscopy. It was found that the high mobility of the thick TiO2 film after heating leads to a significant agglomeration of the Au9 clusters, even when protected by the CrOx layer. The thin TiO2 film has a much lower mobility when being heated, resulting in only minor agglomeration of the Au9 clusters covered with the CrOx layer.

We investigated the effect of adding p-anisaldehyde (AA) solvent to the ink containing poly[[2,60-4,8-di(5-ethylhexylthienyl)benzo[1,2-b:3,3-b]dithiophene][3-fluoro-2[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]](PTB7-Th) and 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:20,30-d0]-s-indaceno[1,2-b:5,6-b0]-dithiophene(ITIC) on the morphology of the active layer. The present study focuses on determining the effect of the additive on the compositions at the surface of the PTB7-Th: ITIC composite and its morphology, forming one side of the interface of the blend with the MoOX electrode, and the influence of the structural change on the performance of devices. Studies of device performance show that the addition of the additive AA leads to an improvement in device performance. Upon the addition of AA, the concentration of PTB7-Th at the surface of the bulk heterojunction (BHJ) increases, causing an increase in surface roughness of the surface of the BHJ. This finding contributes to an understanding of the interaction between the donor material and high work function electrode/interface material. The implications for the interface are discussed.

We have developed two series of p-type conjugated polymers based on poly[2,3-bis-(3-octyloxyphenyl)quinoxaline-5,8-diyl-alt-thiophene-2,5-diyl] (TQ1) polymeric backbone utilizing polar pendant groups, i.e., tertiary amine and pyridine, to achieve switchable solubility in water and ethanol. By balancing the ratio between polar and non-polar side-groups, we could combine green-solvent processability with the manufacturing of functional photovoltaic devices. Due to the unavailability of water/alcohol soluble acceptors, the photovoltaic performance of these new polymers was evaluated using organic solvent by incorporating PC61BM. For water/alcohol soluble partial amine-based polymers, we achieve a maximum power conversion efficiency (PCE) of ∼0.8% whereas alcohol soluble partial pyridine-based polymers show enhanced PCE of ∼1.3% with inverted device structure. We propose that the enhancement in PCE is a result of the reduction in amino-group content and the lower basicity of pyridine, both of which decrease the interaction between functionalized polymers with the anode interface material and reduce the miscibility of the donor and acceptor. Further improvement of the photovoltaic performance, in particular the open-circuit voltage (Voc), was achieved by using an anode buffer layer to mitigate the unfavorable interaction of the amino/pyridine groups with the MoO3 electrode. Our work demonstrated the possibility of substituent modification for conjugated polymers using tertiary amine and pyridine groups to achieve water/alcohol soluble and functional donor materials.

The combination of ultraviolet photoelectron spectroscopy and metastable helium induced electron spectroscopy is used to determine the density of states of the inner and outer coaxial carbon nanotubes. Ultraviolet photoelectron spectroscopy typically measures the density of states across the entire carbon nanotube, while metastable helium induced electron spectroscopy measures the density of states of the outermost layer alone. The use of double-walled carbon nanotubes in electronic devices allows for the outer wall to be functionalised whilst the inner wall remains defect free and the density of states is kept intact for electron transport. Separating the information of the inner and outer walls enables development of double-walled carbon nanotubes to be independent, such that the charge transport of the inner wall is maintained and confirmed whilst the outer wall is modified for functional purposes.

Highly conductive, transparent and flexible planar electrodes were fabricated using interwoven silver nanowires and single-walled carbon nanotubes (AgNW:SWCNT) in a PEDOT:PSS matrix via an epoxy transfer method from a silicon template. The planar electrodes achieved a sheet resistance of 6.6 ± 0.0 Ω/□ and an average transmission of 86% between 400 and 800 nm. A high figure of merit of 367 Ω−1 is reported for the electrodes, which is much higher than that measured for indium tin oxide and reported for other AgNW composites. The AgNW:SWCNT:PEDOT:PSS electrode was used to fabricate low temperature (annealing free) devices demonstrating their potential to function with a range of organic semiconducting polymer:fullerene bulk heterojunction blend systems.

In recent years, self‐assembled monolayers (SAMs) have been proven to work efficiently as hole‐selective materials in both organic solar cells (OSCs) and perovskite solar cells. Although competitive performances are reported with these materials, a mechanistic understanding on device stability remains elusive. This study reveals that while various SAM molecules can increase the indium tin oxide (ITO) work function versus vacuum, they may not consistently result in monolayers that ensure simultaneous improvement in performance and operational stability of devices. Energetically, achieving alignment between the work function of the SAM‐modified electrode and the ionization energy (IE) of the donor is shown to be crucial for a low hole injection barrier, irrespective of the SAM's IE. Light‐induced degradation in the widely used SAM, (2‐(9H‐carbazol‐9‐yl)ethyl) phosphonic acid (2PACz), is identified through diverse aging tests and comprehensive chemical and electronic characterizations. This degradation involves SAM molecule decomposition and chemical reactions with the photoactive layer, contributing further to device degradation. Addressing these challenges, sputtered nickel oxide/SAM bilayers are proposed as hole‐selective contact with tailored interface energetics for both efficient and photostable OSCs, offering a promising alternative to commonly used hygroscopic PEDOT:PSS in OSCs. [ABSTRACT FROM AUTHOR]

Ru is a metal of interest in catalysis. Monodisperse Ru3 clusters as catalytic sites are relevant for the development of catalysts because clusters use significantly lower amounts of precious materials for forming active sites due to the small size of the cluster. However, retaining the mono-dispersity of the cluster size after deposition is a challenge because surface energy could drive both agglomeration and encapsulation of the clusters. In the present work Ru3 clusters are deposited by chemical vapor deposition (CVD) of Ru3(CO)12 and cluster source depositions of bare Ru3 onto radio frequency sputter-deposited TiO2 (RF-TiO2) substrates, TiO2(100), and SiO2. When supported on RF-TiO2, bare Ru3 is encapsulated by a layer of titania substrate material during deposition with a cluster source. Ligated Ru3(CO)12 is also encapsulated by a layer of titania when deposited onto sputter-treated RF-TiO2, but only through heat treatment which is required to remove most of the ligands. The titania overlayer thickness was determined to be 1–2 monolayers for Ru3(CO)12 clusters on RF-TiO2, which is thin enough for catalytic or photocatalytic reactions to potentially occur even without clusters being part of the very outermost layer. The implication for catalysis of the encapsulation of Ru3 into the RF-TiO2 is discussed. Temperature-dependent X-ray photoelectron spectroscopy (XPS), angle-resolved XPS, and temperature-dependent low energy ion scattering (TD-LEIS) are used to probe how the cluster–surface interaction changes due to heat treatment and scanning transmission electron microscopy (STEM) was used to image the depth of the surface from side-on. [ABSTRACT FROM AUTHOR]