ABSTRACT The readily scalable deposition of amorphous oxide semiconductor films is desirable for polymer‐based flexible and large‐area thin‐film transistor technology. Here, the atomic layer deposition (ALD) of p‐type SnO is demonstrated using a new heteroleptic tin(II) precursor. The films exhibit a disordered microstructure, due to the intercalation of fragments of the precursor ligands. Annealing induces crystallization of SnO, as volatile impurities are expelled from the film. Initial examination of bottom gate SnO thin‐film transistors with SiO2 dielectric exhibit a maximum field‐effect mobility of 1.9 cm2 V−1 s−1 and a minimum threshold voltage of 2 V, just before the onset of crystallization. Once capped with an alumina passivation layer, the devices have stable transfer characteristics, post annealing, over a period of two years, and a stable field effect mobility under negative bias stress of 1 MV cm−1 for 2 h at ambient. The disordered SnO semiconductor characteristics make it a candidate for polymer‐based CMOS electronics, where a low thermal budget meets the requirements of polymeric substrates.

This work presents a new family of zincacarborane complexes synthesized from ZnMe2 and [C2B9H13], using neutral two-electron donor ligands: N-heterocyclic carbenes (NHCs) yield the first closo-12-vertex half-sandwich zincocenes, [(NHC)Zn(C2B9H11)] (1-3), while bulkier NHCs form slipped bis-dicarbollide salts (4-5). Use of pyridine leads to the macropolyhedral dimer (6) with a planar {Zn2B2} motif, and triphenylphosphine gives a V-shaped η3-borallyl complex (7). Structures have been confirmed by single-crystal X-ray diffraction and NMR spectroscopy. Computational studies (DFT and QTAIM) show predominantly ionic Zn-dicarbollide bonding with notable polar covalent character. Apparent Zn···Zn interactions are weak electrostatic contacts, and metal-ligand bonding is exclusively to boron atoms. Together, these findings broaden the structural and electronic landscape of zincacarboranes, challenge assumptions about d10 metal-carborane bonding, and offer a new platform for exploring group 12 metallacarborane reactivity.

Di(silylamido)stannylenes find application in chemical synthesis, catalysis and deposition of thin film materials. Homoleptic bis(N-alkyl-substituted-silylamido)stannylenes (i.e. [Sn{NtBu(TMS)}2], TMS = trimethylsilyl) have previously been reported to possess limited thermal stability. Here, we describe the experimental and computational investigation of the thermal decomposition of [Sn{NR(TMS)}2] [R = iPr, Cy, tBu, Ad (Ad = 1-adamantyl), CPh3]. For aliphatic N-alkyl groups, DFT calculations support an intramolecular C(sp3)-H activation by deprotonation of the TMS group via σ-bond metathesis (σBM), which forms a reactive four-membered heterocycle that is followed by disproportionation. When the N-alkyl group is substituted for the trityl group (-CPh3), the homoleptic stannylene could not be isolated, with the deprotonation of a neighbouring ortho-phenyl C(sp2)-H position via σBM occurring at room temperature. The resultant five-membered heterocyclic Sn(II) intermediate rapidly tetramerises into [Sn{κ2-Ph'CPh2N(TMS)}]4, which is stable with respect to disproportionation.

Herein, we report the first thin film transistor TFTs using Sn (HMDS)2 as a precursor for the atomic layer deposition (ALD) of SnO. We subsequently investigate the incorporation of Al-ions in the device channel, from three aluminium sources using low energy ion scattering (LEIS). Alumina is widely exploited in the fabrication of p-type tin monoxide (SnO) TFTs. It has been used as a surface passivation, as a dopant, and as a substrate barrier layer. Alumina is a source of Al3+, which is a compensating donor in SnO. We demonstrate that the intentional incorporation of aluminium into SnO, by introducing alumina cycles during ALD has the effect of increasing the sheet resistance of the SnO films by 105 times and amorphising the film microstructure. Furthermore, the incorporation of Al ions from alumina passivation-capping and barrier layers is revealed at their interfaces with the SnO TFT channel. The transfer characteristics of TFTs fabricated from Al-doped and capped SnO films are used to show the effects of annealing, which are explained in terms of Al ion incorporation. Interdiffusion or incorporation of Al ions into the SnO semiconductor, identified by depth profile LEIS, indicates that auto-doping plays a significant role in modifying the characteristics of SnO TFTs. The application of alumina layers in the design of p-type tin monoxide TFTs must take into account the influence of Al ion incorporation on the semiconducting properties of SnO.

The coordination behavior of a series of [Sn(OR)2] systems modified by substituted amine-bis(phenolate)ligands was investigated. The complexes were synthesised from the reaction of Sn[N(SiMe3)2]2 and the appropriate pro-ligand: N,N-bis(3,5-dimethyl-2-hydroxybenzyl)ethylamine (L1H2), N',N'-bis(2-hydroxy-3,5-dimethylbenzyl)-N,N-dimethylethylenediamine (L2H2), N,N'-bis(3,5-dimethyl-2-hydroxyphenylmethyl)-N,N'-dimethylethylenediamine (L3H2), 1,4-bis(2-hydroxy-3,5-dimethylbenzyl)-1,4-diazepane (L4H2), 2,2',4,4'-tetramethyl-6,6'-piperazine-1,4-diylbis(methylene)-bisphenol (L5H2) and N',N',N'',N''-tetrakis(2-hydroxy-3,5-dimethylbenzyl)-1,2-ethanediamine, and the products were identified as follows: [{L1}Sn]2 (1), [{L2}Sn] (2), [{L3}Sn] (3), [{L4}Sn], (4) and [{L6}Sn2]·(Py)2 (5). Reaction of complex (1) with O2 results in the formation of the Sn(IV) species [{L1}2Sn] (6), the molecular structure of which was also determined.

Photoelectrochemical (PEC) water splitting holds great potential to convert solar energy into hydrogen fuel, establishing an effective method for long-term renewable energy storage. Herein, a simple and effective approach is presented for fabricating thin films of alpha-Fe2O3 and BiFeO3 for use as PEC photoanodes via aerosol-assisted chemical vapor deposition (AACVD). A new Fe(III) precursor bearing an amino-tris-tert-butoxide ligand is designed and coupled with a Bi-based precursor bearing the same ligand framework to deposit nanostructured films of alpha-Fe2O3 and BiFeO3 with high phase purity. Under 1 sun solar irradiation alpha-Fe2O3 and BiFeO3 yielded a photocurrent density of 0.38 and 0.42 mA cm-1 at 1.23 VRHE, respectively. A study reveals that the bespoke precursors exhibit remarkable compatibility with one another, producing films of significantly higher quality compared to those produced with more conventional precursors not optimized for AACVD.

We report here the synthesis of a novel class of precursors for the chemical vapor deposition (CVD) of thin films of metallic, face-centered cubic (fcc) nickel. The complexes are simple and inexpensive to synthesize, possess high volatility (vapor pressure = 0.1 Torr at 40 °C), and enable rapid deposition rates of nickel under CVD conditions (up to 6.5 nm/min at 250 °C). We show that the deposited nickel films have high elemental purity (>99 at%), resistivity comparable to bulk nickel (7-23 μΩ·cm cf. 6.93 μΩ·cm), exhibit shallow surface features (ca. ± 10 nm), and very low surface roughness (RMS = 2.72 nm). These data compare favorably with those of the current state-of-the-art metallic nickel CVD precursors.

Green hydrogen production is a key area of importance for advancing into a completely sustainable world, not only for its use in industry and ammonia production, but also for its potential as a new fuel. One promising method for generating green hydrogen is light-driven water splitting using photoelectrodes. Here, a bismuth vanadate (BiVO4) photoanode deposition process was developed using new, bespoke dual-source precursors, tailored for use in aerosol-assisted chemical vapour deposition (AACVD). The resulting thin films were highly nanostructured and consisted of phase-pure monoclinic BiVO4. Pristine films under 1 sun solar irradiation yielded photocurrent densities of 1.23 mA cm-2 at 1.23 V vs RHE and a peak incident photon-electron conversion efficiency (IPCE) of 82 % at 674 nm, the highest performance of any CVD-grown BiVO4 film to date. A new, AACVD-compatible WO3 precursor was subsequently designed and synthesised for the deposition of W-doped BiVO4 within the same single deposition step.

The β-diketiminato carboranyl complexes, [(BDI)Ae(o-C2B10H11)] (Ae = Mg or Ca), have been synthesised and [(BDI)Mg(o-C2B10H11)] reacted with NHCIPrMCl to provide NHCIPrM(o-C2B10H11), rare C-bonded coinage metal derivatives of (o-C2B10H11)−.

A series of iso-carbamate complexes have been synthesized by the reaction of [(SnOPr)-O-II(-Pr-i)(2)] or [Sn-II(O-t Bu)(2)] with either aryl or alkyl isocyanates, ONC-R (R = 2,4,6-trimethylphenyl (Mes), 2,6-diisopropylphenyl (Dipp), isopropyl (Pr-i), cyclohexyl (Cy) and tert-butyl (Bu-t)). In the case of aryl isocyanates, mono-insertion occurs to form structurally characterized complexes [Sn{kappa(2)-N,O-R-NC((OPr)-Pr-i)O}(mu-(OPr)-Pr-i)](2) (1: R = Mes, 2: R = Dipp) and [Sn{kappa(2)-N,O-R-NC(O-t Bu)O}(mu-(OBu)-Bu-t)](2) (3: R = Mes, 4: R = Dipp). The complicated solution-state chemistry of these species has been explored using H-1 DOSY experiments. In contrast, reactions of tin(II) alkoxides with alkyl isocyanates result in the formation of bis-insertion products [Sn{kappa(2)-N,O-R-NC((OPr)-Pr-i)O}(2)] (5: R = Pr-i, and 6: R = Cy) and [Sn{kappa(2)-N,O-R-NC((OBu)-Bu-t)O}(2)] (7: R = Pr-i, 8: R = Cy), of which complexes 6-8 have also been structurally characterized. H-1 NMR studies show that the reaction of Bu-t-NCO with either [Sn((OPr)-Pr-i)(2)] or [Sn((OBu)-Bu-t)(2)] results in a reversible mono-insertion. Variable-temperature 2D H-1-H-1 exchange spectroscopy (VT-2D-EXSY) was used to determine the rate of exchange between free Bu-t-NCO and the coordinated Bu-t-iso-carbamate ligand for the {(OPr)-Pr-i} alkoxide complex, as well as the activation energy (E-a = 92.2 +/- 0.8 kJ mol(-1)), enthalpy (Delta H double dagger = 89.4 +/- 0.8 kJ mol(-1)), and entropy (Delta S double dagger = 12.6 +/- 2.9 J mol(-1) K-1) for the process [Sn((OPr)-Pr-i)(2)] + Bu-t-NCO <-> [Sn{kappa(2)-N,O-Bu-t-NC((OPr)-Pr-i)O}((OPr)-Pr-i)]. Attempts to form Sn(II) alkyl carbonates by the insertion of CO2 into either [Sn((OPr)-Pr-i)(2)] or [Sn((OBu)-Bu-t)(2)] proved unsuccessful. However, Sn-119{H-1} NMR spectroscopy of the reaction of excess CO2 with [Sn((OPr)-Pr-i)(2)] reveals the presence of a new Sn(II) species, i.e., [((PrO)-Pr-i)Sn((O2COPr)-Pr-i)], VT-2D-EXSY (H-1) of which confirms the reversible alkyl carbonate formation (E-a = 70.3 +/- 13.0 kJ mol(-1); Delta H double dagger = 68.0 +/- 1.3 kJ mol(-1) and Delta S double dagger = -8.07 +/- 2.8 J mol(-1) K-1).

A series of zinc and cadmium thioamidate complexes have been synthesised, characterised and their thermal properties assessed for their potential application in the AACVD of metal sulfide thin films.

Hematite (α-Fe2O3) is one of the most promising and widely used semiconductors for application in photoelectrochemical (PEC) water splitting, owing to its moderate bandgap in the visible spectrum and earth abundance. However, α-Fe2O3 is limited by short hole-diffusion lengths. Ultrathin α-Fe2O3 films are often used to limit the distance required for hole transport, therefore mitigating the impact of this property. The development of highly controllable and scalable ultrathin film deposition techniques is therefore crucial to the application of α-Fe2O3. Here, a plasma-enhanced atomic layer deposition (PEALD) process for the deposition of homogenous, conformal, and thickness-controlled α-Fe2O3 thin films (<100 nm) is developed. A readily available iron precursor, dimethyl(aminomethyl)ferrocene, was used in tandem with an O2 plasma co-reactant at relatively low reactor temperatures, ranging from 200 to 300 °C. Optimisation of deposition protocols was performed using the thin film growth per cycle and the duration of each cycle as optimisation metrics. Linear growth rates (constant growth per cycle) were measured for the optimised protocol, even at high cycle counts (up to 1200), confirming that all deposition is ‘true’ atomic layer deposition (ALD). Photoelectrochemical water splitting performance was measured under solar simulated irradiation for pristine α-Fe2O3 deposited onto FTO, and with a α-Fe2O3-coated TiO2 nanorod photoanode.

Amorphous molybdenum sulfide (a-MoSx) is a promising candidate to replace noble metals as electrocatalysts for the hydrogen evolution reaction (HER) in electrochemical water splitting. So far, understanding of the activity of a-MoSx in relation to its physical (e.g., porosity) and chemical (e.g., Mo/S bonding environments) properties has mostly been derived from bulk electrochemical measurements, which provide limited information about electrode materials that possess microscopic structural heterogeneities. To overcome this limitation, herein, scanning electrochemical cell microscopy (SECCM) has been deployed to characterize the microscopic electrochemical activity of a-MoSx thin films (ca. 200 nm thickness), which possess a significant three-dimensional structure (i.e., intrinsic porosity) when produced by electrodeposition. A novel two-step SECCM protocol is designed to quantitatively determine spatially resolved electrochemical activity and electrochemical surface area (ECSA) within a single, high-throughput measurement. It is shown for the first time that although the highest surface area (e.g., most porous) regions of the a-MoSx film possess the highest total activity (measured by the electrochemical current), they do not possess the highest specific activity (measured by the ECSA-normalized current density). Instead, the areas of highest specific activity are localized at/around circular structures, coined "pockmarks", which are tens to hundreds of micrometers in size and ubiquitous to a-MoSx films produced by electrodeposition. By coupling this technique with structural and elemental composition analysis techniques (scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy) and correlating ECSA with activity and specific activity across SECCM scans, this work furthers the understanding of structure-activity relations in a-MoSx and highlights the importance of local measurements for the systematic and rational design of thin film catalyst materials.

P-type SnO thin films have been deposited using multiple pulses of a novel Sn(ii) precursor per ALD cycle. The study looks at the effect on TFT performance and AFM analysis has explored the change in the growth processes during deposition.

This review outlines the underexplored molecular chemistry bottom-up approach of bespoke precursor design in photoelectrode development for photoelectrochemical water splitting.

New and bespoke precursors have been used to fabricate mixed anatase-rutile TiO 2 with exceptional photoelectrochemical performance towards water splitting.

Analogous to the ubiquitous alkoxide ligand, metal boroxide and boryloxy complexes are an underexplored class of hard anionic O- ligand. A new series of amine-stabilized Li, Sn(II), and Zn boryloxy complexes, comprising electron-rich tetrahedral boron centers have been synthesized and characterized. All complexes have been characterized by one-dimensional (1D), two-dimensional (2D), and DOSY NMR, which are consistent with the solid-state structures unambiguously determined via single-crystal X-ray diffraction. Electron-rich μ2- (Sn and Zn) and μ3- (Li) boryloxy binding modes are observed. Compounds 6-9 are the first complexes of this class, with the chelating bis- and tris-phenol ligands providing a scaffold that can be easily functionalized and provides access to the boronic acid pro-ligand, hence allowing facile direct synthesis of the resulting compounds. Computational quantum chemical studies suggest a significant enhancement of the π-donor ability of the amine-stabilized boryloxy ligand because of electron donation from the amine functionality into the p-orbital of the boron atom.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

The reactivity of the racemic N-heterocyclic stannylene [{MeHCN(tBu)}Sn] (1) with the chalcogenide elements O2, S, Se, and Te has been investigated. In the case of the reaction of 1 with molecular oxygen, the cyclic tristannoxane complex [{MeHCN(tBu)}2Sn(μ-O)]3 (3) was isolated and characterised. NMR studies (1H, 13C, and 119Sn) show the formation of D3- and C2- symmetric assemblies. The reaction of 1 with S, Se, and Te, respectively, yielded the cyclo-distannachalcogenide complexes, [{MeHCN(tBu)}2Sn(μ-E)]3 (4: E = S, 5: E = Se, 6: E = Te), again with multinuclear NMR studies proving the formation of C2- and Cs-symmetric assemblies. Single crystal X-ray diffraction studies have been used to elucidate the molecular structures of the products of oxidative addition, 3, 4, 5, and 6.