Hybrid metal halide perovskite solar cells (PSCs) are the most promising candidates to share the future energy market with silicon solar cells thanks to their excellent photovoltaic (PV) properties in single junction and tandem applications. Although PSCs are already highly efficient, their performance can be further improved by passivating the perovskite boundaries and improving current-voltage hysteresis. Here, we implement a double-sided passivation approach to enhance the perfor-mance of n-i-p structured PSCs, showing how passivating on either side improves cell performance. The electron-collecting side was passivated with biphenyl-4,4-dicarboxylic acid (BPDC), and n-octyl ammonium bromide was used to passivate the hole-collecting side. The power conversion efficiency of the champion cell improved from 18.7 % for control to 20.9 % when double-sided passivation was implemented. Surface imaging showed how the surface boundaries improved following passivation, resulting in better open circuit voltages (VOC) and fill factors. In addition, passivation creates a barrier for ion migration, improving J-V hysteresis and stability in the process. The champion cell displayed a VOC of 1192 mV with double-sided passivation, incurring only-390 mV loss, thereby achieving a high VOC with a mid-bandgap perovskite. Preliminary degradation testing in ambient conditions shows that double-sided passivation also improves the stability of the cells by impeding ion migration.

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.

Functionalization at interface of the electron transport layer and the organic polymeric donor and non-fullerene acceptor bulk heterojunction layer in photovoltaic devices that have an inverted structure, is a unique strategy for improving performance. Here we demonstrate improved interfacial nanomorphology of the well-known PTB7-Th donor and IEICO-4F acceptor bulk heterojunction (BHJ) on an atomic layer deposited (ALD) ultrathin titanium oxide (TiO2) passivated sol-gel grown zinc oxide (ZnO) electron transport bilayer and highlight how this is correlated to the overall organic photovoltaic device performance. Synchrotron-based grazing incidence wide-angle X-ray scattering (GIWAXS) has been used to demonstrate an enhanced face-on conformation within the BHJ with highly crystalline ZnO/TiO2/BHJ layers and this is greatest for the very thinnest of TiO2 layers on ZnO (ZnT1), from just two deposition cycles, relative to both four (ZnT2) and eight (ZnT3) cycles. Photovoltaic devices with BHJs grown over ZnT1, showed an overall average increase of 30.3 +/- 0.5 % in the power conversion efficiency (PCE 10.3 +/- 0.5 %), a 14.3 +/- 1 % increase in the fill-factor, FF (60.1 +/- 1 %), 2.9 +/- 0.05 % improvement in Voc (0.70 +/- 0.05 mV) and 13.6 +/- 0.5 % higher JSc (24.2 +/- 0.5 mA/cm2), compared to the control device,with a best efficiency of 11.1 +/- 0.5 % PCE, 61.9 +/- 1 % FF, 0.70 +/- 0.5 mV Voc and 25.0 +/- 0.5 mA/cm2 Jsc. We conclude that the molecular crystal conformation of the organic donor acceptor BHJ layer can be partly controlled through the ETL along with an enhanced organic inorganic interface which strongly influences the OPV performance.

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.

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.

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.

Chemical vapor deposition (CVD) has great potential to produce graphene films at large-scale. However, CVD production of graphene films usually requires a catalytic metal substrate, such as copper. Recently we have developed a new method to grow graphene films directly on crystalline silicon wafers with a thermally grown 300 nm oxide layer, using a seeded-CVD growth approach. The use of methane as the feedstock and optimized graphene seeds has led to enhanced film formation, which SEM, X-ray photo-electron and Raman spectroscopies indicate consist of graphene layers formed by the coalescence of expanding “graphene seeds”. The resultant films have regions of single graphene crystallites within them as a result of lateral growth of the seeds. In addition, we have observed that the unilateral conductivity of the graphene films is consistent with the presence of graphene nanoribbons and as such has potential application in device fabrication.

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.

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 step edges and intrinsic atomic structure of single-crystal substrate play a critical role in determining the growth pathways of transition metal dichalcogenide (TMD) grains, particularly whether the TMDs will grow into wafer-scale single-crystal or anisotropic nanoribbons. Hereby, we investigate the growth behaviours of the MoS2 nanograins on (0001) and ( $$1\bar 102$$ ) sapphire substrates. On one hand, the step edges formed on the (0001) surface after thermal treatment are found to promote the macroscopic aggregation of MoS2 nanograins and to form unidirectional large triangular islands along with the < $$11\bar 20$$ > steps in the annealing process, while on the pristine (0001) surface, the MoS2 nanograins grow into a random network-like pattern. Moreover, oxygen treatment on the substrate can further enhance the growth of MoS2 nanograins. Transmission electron microscopy and fast Fourier transform patterns reveal that the substrate could modulate the orientation of MoS2 nanograins during their growing process. On the other hand, the MoS2 nanograins on the ( $$1\bar 102$$ ) surface could self-assemble into one-dimensional nanoribbons due to the strong structural anisotropy of the substrate. In addition, the ratio of Raman intensities for peaks that correspond to the $${\rm{E}}_{2{\rm{g}}}^1$$ and A1g phonon modes shows a linear relationship with the grain size due to the change of the “phonon confinement”. Moreover, new peaks located at 226 and 280 cm−1 can be observed in the off-resonant and resonant Raman spectra for the MoS2 nanograin samples, respectively, which can be attributed to the scatterings from the edges of as-fabricated MoS2 nanostructures.

Small grain size and near-horizontal grain boundaries are known to be detrimental to the carrier collection efficiency and device performance of pure-sulfide Cu2ZnSnS4 (CZTS) solar cells. However, forming large grains spanning the absorber layer while maintaining high electronic quality is challenging particularly for pure sulfide CZTS. Herein, a liquid-phase-assisted grain growth (LGG) model that enables the formation of large grains spanning across the CZTS absorber without compromising the electronic quality is demonstrated. By introducing a Ge-alloyed CZTS nanoparticle layer at the bottom of the sputtered precursor, a Cu-rich and Sn-rich liquid phase forms at the high temperature sulfurization stage, which can effectively remove the detrimental near-horizontal grain boundaries and promote grain growth, thus greatly improving the carrier collection efficiency and reducing nonradiative recombination. The remaining liquid phase layer at the rear interface shows a high work function, acting as an effective hole transport layer. The modified morphology greatly increases the short-circuit current density and fill factor, enabling 10.3% efficient green Cd-free CZTS devices. This work unlocks a grain growth mechanism, advancing the morphology control of sulfide-based kesterite solar cells.

The performance of non‐fullerene, polymer bulk heterojunction (BHJ) organic photovoltaic devices has a significant correlation with the molecular morphology of the donor and acceptor. The authors show that small organic molecules coordinated to a metal oxide, an electron transport seed layer (ETSL), can profoundly modify the donor:acceptor molecular morphology of inverted organic photovoltaic (OPV) devices. Using grazing incidence wide angle X‐ray scattering (GIWAXS), the authors show that a PTB7‐Th:IEICO‐4F BHJ active layer has a higher degree of face‐on molecular alignment on ETSL‐1 (biphenyl‐4,4′‐dicarboxylic acid, coordinated to ZnO), whilst for naphthalene‐2,6‐dicarboxylic acid coordinated to ZnO (ETSL‐2), it is reduced. Devices of PTB7‐Th:IEICO‐4F BHJ prepared on ETSL‐1 had a 19.91% increase in the average power conversion efficiency (PCE), a 1.56% increase in the fill factor (FF), and a 16.66 ± 0.2% enhancement in the short circuit current density. The observed improvements are believed to be due to significant modifications to the oxide‐BHJ interfacial region of ETSL‐1, namely the elimination of nano‐ridges and defect centers, along with an enhanced wettability. These factors can be correlated with the enhanced device performances, leading to the conclusion that the modulation of the molecular morphology of donor:acceptor blends by ETSL‐1 has a broad impact on improving OPV cell efficiencies.

Effectively incorporating alkali metals or alternative isovalent cations into Cu2ZnSnS4 (CZTS) is considered one of the most promising strategies for realizing a step‐change improvement in the photovoltaic device performance. Herein, the local distribution of Na and Cd by a moisture‐assisted postdeposition annealing (MAPDA) treatment combined with a subsequent heterojunction heat treatment is manipulated. The MAPDA treatment facilitates the controllable reduction of the Na concentration, thus promoting the spontaneous diffusion of Cd into the heterojunction region. A subsequent 150 °C low‐temperature heterojunction heat treatment after MAPDA treatment enables further modification of Cd and Na distributions, leading to significantly enhanced optoelectronic properties at the CZTS/CdS heterojunction and greatly improved device performance with a peak conversion efficiency of 9.40%. The modified heterojunction significantly improves quasi‐Fermi‐level splitting under low‐photon injection, making CZTS solar cells more feasible in low‐light applications. This work provides an effective approach to simultaneously manipulate the distribution of Na and Cd, enabling pronounced modification of the heterojunction quality of CZTS solar cells and boost of conversion efficiencies. Insights gleaned herein may also be applicable to manipulating other critical trace elements in chalcogenide materials in general.

Sulfide kesterite Cu2ZnSnS4 (CZTS) solar cells, containing earth-abundant and environmentally benign constituents, are regarded as promising candidates for thin-film photovoltaic technologies. CZTS device performance, however, is currently limited by severe nonradiative recombination caused by abundant deep-level defects. Herein, an effective defect engineering approach for high bandgap CZTS solar cells using a newly introduced moisture-assisted post-deposition annealing treatment is reported. This treatment modifies the local chemical composition within the heterojunction and CZTS grain boundaries and enhances the incorporation of Cd within the CZTS layer during CdS deposition. Cd not only accumulates at the grain boundaries, but it also presents in grain interiors where it occupies Cu lattice sites. The overall modification of the local chemical environment suppresses deep level defects and activates relatively shallow acceptor Cu-Zn antisites and Cu vacancies, giving rise to remarkably improved device performance. This work opens a new direction for defect engineering of kesterite materials, which may also be applicable to other thin film semiconductors.

The production of graphene films is of importance for the large-scale application of graphene-based materials; however, there is still a lack of an efficient and effective approach to synthesize graphene films directly on dielectric substrates. Here, we report the controlled growth of ultrathin carbon films, which have a similar structure to graphene, directly on silicon substrates in a process of seeded chemical vapor deposition (CVD). Crystalline silicon with a thermally grown 300 nm oxide layer was first treated with 3-trimethoxysilyl-1-propanamine (APS), which was used as an anchor point for the covalent deposition of small graphene flakes, obtained from graphite using the Hummers' method. Surface coverage of these flakes on the silicon substrate was estimated by scanning electron microscopy (SEM) to be around only 0.01% of the total area. By treating the covalently deposited graphene as seeds for CVD growth, the coverage was increased to >40% when using ethanol as the carbon source. Examination of the carbon thin films with SEM, X-ray photoelectron spectroscopy, and Raman spectroscopy indicated that they consist of domains of coherent, single-layer graphene produced by the coalescence of the expanding graphene islands. This approach potentially lends itself to the production of high-quality graphene films that may be suitable for device fabrication.

Indigo-carmine-mediated direct alkaline fuel cells have demonstrated superior power outputs over their non-mediated counterparts. Currently, the mechanism of mediation and stability of mediators are poorly understood. Upon exposure to highly alkaline solutions, we observed that the redox action of indigo carmine diminished, and significant currents were produced, indicating substantial degradation of the dye. The decomposition of indigo carmine at high pH and a poor thermal stability suggest that alternative mediators with low toxicity may be required to enable the widespread application of this device type.

Breakdown and utilization of cellulose are critical for the bioenergy sector; however, current cellulose-to-energy conversion schemes often consume large quantities of unrecoverable chemicals, or are expensive, due to the need for enzymes or high temperatures. In this paper, we demonstrate a new method for converting cellulose into soluble compounds using a mixture of Fe2+ and Fe3+ as catalytic centers for the breakdown, yielding Fe3O4 nanoparticles during the hydrothermal process. Iron precursors transformed more than 61% of microcrystalline cellulose into solutes, with the composition of the solute changing with the initial Fe3+ concentration. The primary products of the breakdown of cellulose were a range of aldaric acids with different molecular weights. The nanoparticles have concentration-dependent tuneable sizes between 6.7 and 15.8 nm in diameter. The production of value-added nanomaterials at low temperatures improves upon the economics of traditional cellulose-to-energy conversion schemes with the precursor value increasing rather than deteriorating over time.

An unprecedented spin cluster-based network architecture {[NiII 2 (pdaa)(OH)2 (H2 O)]n (H2 pdaa=1,4-phenylene diacetic acid)}, comprising 1D linear chains of NiII ions crosslinked via Ni4 O4 cubanes, forms under hydrothermal conditions; this 3D coordination network exhibits magnetic ordering at 23.9 K as well as a second magnetic ordering process at 2.8 K likely associated with a structural phase transition.

Four eyes see more than two: Operando EPR, XANES/EXAFS, ATR-IR, and UV/Vis spectroscopy have been coupled in the same experiment to complete the mechanistic puzzle in selective aerobic alcohol oxidation by a copper-TEMPO catalyst. The reaction is driven by a single CuI/CuII redox cA remarkable Ni4O4–cubane-based coordination framework has been shown to display unusual low-temperature magnetic behavior. The 3D coordination network consists of perpendicular chains of NiII ions linked by 1,4-phenylene diacetate ligands and bridged by the Ni4O4–cubane units. It was found to undergo a magnetic ordering at ∼24 K into an antiferromagnetic or partially spin-compensated phase, but then to also display a pronounced magnetic hysteresis below ∼3 K. The authors conclude that this is due to a structural phase transition. More information can be found in the Full Paper by P. Kögerler, J. A. Stride, et al. on page 7589.