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In this work, we report the synthesis of a room-temperature-stable electride (RoSE) reagent, namely K⁺(LiHMDS)e⁻ (1) (HMDS: 1,1,1,3,3,3-hexamethyldisilazide), from accessible starting materials (potassium metal and LiHMDS) via mechanochemical ball milling at 20 mmol scale. Despite its amorphous nature, the presence of anionic electrons in 1, key diagnostic criteria for an electride, was confirmed by both experimental and computational studies. Therefore, by definition, 1 is an electride. Utilizing its anionic electrons, electride reagent 1 exhibited a versatile reactivity profile that includes (1) mediation of C–H activation and C–C coupling of benzene and pyridine and (2) mediation of solvent-free Birch reduction. This work proves the concept of facile mechanochemical synthesis of a room-temperature-stable electride, and it introduces electride 1 to the synthetic chemistry community as a versatile reagent.

Emerging solar energy conversion and energy storage technologies play a vital role in solving the present energy crisis and achieving carbon net zero. Currently, they are limited by the use of inefficient, unstable and expensive charge transport materials. The development of new charge transport materials is still far behind the efforts that have been made to develop the light-absorbing or other components. Metalorganic coordination compounds offer unique sets of properties as hybrids between conductive metals and tunable organic molecules. The coordination of the metal centers is crucial to control in order to maximise the solar cell efficiency - or undesired electronic recombination limits the power output. Tetradentate ligands allow copper complexes to dynamically switch between dimers or monomers, pending the oxidation state of the metal ions. The high energy barrier for the reduction of Cu^II monomers prevents electron transfer across the TiO₂|dye|electrolyte interface: Interfacial recombination is reduced and the dye-sensitised solar cells achieve greater photovoltages. Coordination complexes linked into low-dimensional coordination polymers afford charge transport with an electrical conductivity as high as 0.1 S m^-1 via band-like conduction at room temperature, needless of cationic dopants. The polymers rapidly extract photoexcited charges from halide perovskite films. 14% power conversion efficiency were recorded from a perovskite solar cell based on a carbon counter electrode. The solar cell stability was much increased compared to heavily doped organic hole conductors. Emerging dye-sensitised solar cells excel especially under ambient conditions, and have been proposed as power sources for dispatched electronic devices (the Internet of things), in place of single-use and difficult-to-recycle batteries. Through tailoring of the optical response and the electrolyte composition, power conversion efficiencies of 37.5% with photovoltages of 1.00 V at 1000 lux (fluorescent lamp) are demonstrated. The increased performance is identified to stem from reduced interfacial recombination by transient photovoltage methods as well as electrochemical impedance spectroscopy. A series of prototype tests underline the feasibility of light harvesters as power sources for electronic devices, executing sophisticated computation tasks such as machine learning. The devices self-optimise their energy consumption; adaptive sleep and small supercapacitors allow to sustain device operation during periods of fluctuating energy availability.

Making large datasets findable, accessible, interoperable and reusable could accelerate technology development. Now, Jacobsson et al. present an approach to build an open-access database and analysis tool for perovskite solar cells. Large datasets are now ubiquitous as technology enables higher-throughput experiments, but rarely can a research field truly benefit from the research data generated due to inconsistent formatting, undocumented storage or improper dissemination. Here we extract all the meaningful device data from peer-reviewed papers on metal-halide perovskite solar cells published so far and make them available in a database. We collect data from over 42,400 photovoltaic devices with up to 100 parameters per device. We then develop open-source and accessible procedures to analyse the data, providing examples of insights that can be gleaned from the analysis of a large dataset. The database, graphics and analysis tools are made available to the community and will continue to evolve as an open-source initiative. This approach of extensively capturing the progress of an entire field, including sorting, interactive exploration and graphical representation of the data, will be applicable to many fields in materials science, engineering and biosciences.

The TiO₂ blocking layer in dye-sensitized solar cells is the most difficult component to evaluate at thicknesses below 50 nm, but it is crucial for the power conversion efficiency. Here, the electrode capacitance of TiO₂ blocking layers is tested in aqueous [Fe(CN)₆]^3–/4– and correlated to the performance of photoanodes in devices based on a [Cu(tmby)₂]^2+/+ electrolyte. The effects of the blocking layer on electronic recombination in the devices are illustrated with transient photovoltage methods and electrochemical impedance analysis. We have thus demonstrated a feasible and facile method to assess TiO₂ blocking layers for the fabrication of dye-sensitized solar cells.

Conductive coordination polymers are hybrid materials with the potential to be implemented in the next generation of electronic devices, owing to several desirable properties. A decade ago, only a few scattered examples exhibiting conductivity existed within this class of materials, yet today groups of coordination polymers possess electrical conductivities and mobilities that rival those of inorganic semiconductors. Many currently emerging energy harvesting and storage technologies are limited by the use of inefficient, unstable, and unsustainable charge transport materials with little tunability. Coordination polymers, on the other hand, offer great electrical properties and fine-tunability through their assembly from molecular building blocks. Herein, the structure-function relationship of these building blocks and how to characterize the resulting materials are examined. Solution processability allows devices to step away drastically from conventional fabrication methods and enables cheap production from earth abundant materials. The ability to tune the electrical and structural properties through modifications at the molecular level during the material synthesis stages allows for a large design space, opening the door to a wide spectrum of applications in environmentally friendly technologies, such as molecular wires, photovoltaics, batteries, and sensors. Sustainable, high-performing charge transport materials are crucial for the continued advance of emerging molecular technologies. This review aims to provide examples of how the promising properties of coordination polymers have been exploited to accelerate the development of molecular devices.

Emerging technologies in solar energy will be critical in enabling worldwide society in overcoming the present energy challenges and reaching carbon net zero. Inefficient and unstable charge transport materials limit the current emerging energy conversion and storage technologies. Low-dimensional coordination polymers represent an alternative, unprecedented class of charge transport materials, comprised of molecular building blocks. Here, we provide a comprehensive study of mixed-valence coordination polymers from an analysis of the charge transport mechanism to their implementation as hole-conducting layers. Cu-II dithiocarbamate complexes afford morphology control of 1D polymer chains linked by (CuI2X2) copper halide rhombi. Concerted theoretical and experimental efforts identified the charge transport mechanism in the transition to band-like transport with a modeled effective hole mass of 6m(e). The iodide-bridged coordination polymer showed an excellent conductivity of 1 mS cm(-1) and a hole mobility of 5.8 10(-4) cm(2) (V s)(-1) at room temperature. Nanosecond selective hole injection into coordination polymer thin films was captured by nanosecond photoluminescence of halide perovskite films. Coordination polymers constitute a sustainable, tunable alternative to the current standard of heavily doped organic hole conductors.

Summary Conventional redox mediators based on metal coordination complexes undergo electron transfer through the change in oxidation state of the metal center. However, electron transfer kinetics are offset toward preferred oxidation states when preorganized ligands constrain the reorganization of the coordination sphere. In contrast, we report here on dimeric copper(II/I) redox couples, wherein the extent of oxidation/reduction of two metal centers dictates the dynamic formation of dimer and monomer complexes: the dimeric (Cu(I))2 transitions to monomers of Cu(II). The bis(thiazole/pyrrole)-bipyridine tetradentate ligands stabilize both oxidation states of the unique redox systems. The dynamic dimer redox mediators offer a viable two-electron redox mechanism to develop efficient hybrid solar cells through inhibited recombination and rapid charge transport. Density functional theory calculations reveal inner reorganization energies for single-electron transfer as low as 0.27 eV, marking the dimeric complexes superior redox systems over single complexes as liquid and potentially solid-state electrolytes.

Dye-sensitized solar cells are promising candidates for low-cost indoor power generation applications. However, they currently suffer from complex fabrication and stability issues arising from the liquid electrolyte. Consequently, the so-called zombie cell was developed, in which the liquid electrolyte is dried out to yield a solid through a pinhole after cell assembly. We report a method for faster, simpler, and potentially more reliable production of zombie cells through direct and rapid drying of the electrolyte on the working electrode prior to cell assembly, using an iodide-triiodide redox couple electrolyte as a basis. These "rapid-zombie" cells were fabricated with power conversion efficiencies reaching 5.0%, which was larger than the 4.5% achieved for equivalent "slow" zombie cells. On a large-area cell of 15.68 cm(2), over 2% efficiency was achieved at 0.2 suns. After 12 months of dark storage, the "rapid-zombie" cells were remarkably stable and actually showed a moderate increase in average efficiencies.

The impending implementation of billions of Internet of Things and wireless sensor network devices has the potential to be the next digital revolution, if energy consumption and sustainability constraints can be overcome. Ambient photovoltaics provide vast universal energy that can be used to realise near-perpetual intelligent IoT devices which can directly transform diffused light energy into computational inferences based on artificial neural networks and machine learning. At the same time, a new architecture and energy model needs to be developed for IoT devices to optimize their ability to sense, interact, and anticipate. We address the state-of-the-art materials for indoor photovoltaics, with a particular focus on dye-sensitized solar cells, and their effect on the architecture of next generation IoT devices and sensor networks.

A new generation of octahedral iron(ii)-N-heterocyclic carbene (NHC) complexes, employing different tridentate C<^>N<^>C ligands, has been designed and synthesized as earth-abundant photosensitizers for dye sensitized solar cells (DSSCs) and related solar energy conversion applications. This work introduces a linearly aligned push-pull design principle that reaches from the ligand having nitrogen-based electron donors, over the Fe(ii) centre, to the ligand having an electron withdrawing carboxylic acid anchor group. A combination of spectroscopy, electrochemistry, and quantum chemical calculations demonstrate the improved molecular excited state properties in terms of a broader absorption spectrum compared to the reference complex, as well as directional charge-transfer displacement of the lowest excited state towards the semiconductor substrate in accordance with the push-pull design. Prototype DSSCs based on one of the new Fe NHC photosensitizers demonstrate a power conversion efficiency exceeding 1% already for a basic DSSC set-up using only the I-/I-3(-) redox mediator and standard operating conditions, outcompeting the corresponding DSSC based on the homoleptic reference complex. Transient photovoltage measurements confirmed that adding the co-sensitizer chenodeoxycholic acid helped in improving the efficiency by increasing the electron lifetime in TiO2. Time-resolved spectroscopy revealed spectral signatures for successful ultrafast (<100 fs) interfacial electron injection from the heteroleptic dyes to TiO2. However, an ultrafast recombination process results in undesirable fast charge recombination from TiO2 back to the oxidized dye, leaving only 5-10% of the initially excited dyes available to contribute to a current in the DSSC. On slower timescales, time-resolved spectroscopy also found that the recombination dynamics (longer than 40 mu s) were significantly slower than the regeneration of the oxidized dye by the redox mediator (6-8 mu s). Therefore it is the ultrafast recombination down to fs-timescales, between the oxidized dye and the injected electron, that remains as one of the main bottlenecks to be targeted for achieving further improved solar energy conversion efficiencies in future work.