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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. [ABSTRACT FROM AUTHOR]

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 CuZn 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. [ABSTRACT FROM AUTHOR]

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 1 ¯ 02 ) 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 2 ¯ 0 > 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 1 ¯ 02 ) 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 E 2 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. [ABSTRACT FROM AUTHOR]

The mixed-valence double salt K3(MnO4)(sub 2) crystallizes in space group P2(sub 1)/m with Z=2. The results of the polarized neutron diffraction study of K3 (MnO4)(sub 2) are discussed.

The dynamics of the polyaromatic cores are of vital importance as they help in examining the electrical conductivities of the columns. It is found that the dynamics of the inner core and the alkyl tails of discotics are strongly correlated.

A direct, sensitive inelastic neutron scattering spectroscopic study enables the quantitative determination of magnetic transitions in exchange-coupled oxo-centered triiron(III) complexes. The complex, (Fe3O(O2CCD3)6(C5D5N)3)NO3, has isosceles triangular cluster, while the clusters in K5(Fe3O(SO4)6(D2O)3). 6H2O and (Fe3O(O2CC(CD3)3)6(DOCD3)3)Cl are described as scalene. Magnetic Jahn-Teller effect accounts for the deviation of clusters from equilateral symmetry.