Eva To accelerate the materials discovery and development process for a sustainable technology advancement it is imperative to explore and develop combined high-throughput material synthesis and analysis work fl ows. In this work, we investigate a method of combinatorial inkjet-printing to tune the composition of the inorganic cesium lead mixed halide perovskite solid solution, CsPb(Br x I 1 (cid:1) x ) 3 . The compositional variation is achieved by simultaneous printing of di ff erent precursor inks with multiple printheads and controlled by varying the number of droplets printed by each printhead throughout the sample. The droplet placement is optimised through an algorithm that allows maximum mixing of the combined inks. The local compositional homogeneity of thin- fi lm samples was investigated as a function of the printing resolution by micrometer-resolution X-ray fl uorescence and synchrotron-based grazing-incidence wide-angle X-ray scattering. We show that a combinatorial library of ten compositions between CsPbI 3 and CsPbBr 2 I, printed using the developed algorithm, is locally homogeneous for the optimised printing parameters. An implementation of the algorithm in the high-level programming language Python is provided for easy use in other systems.

A new method for droplet placement in combinatorial inkjet printing, validated by synchrotron micro-spot X-ray diffraction mapping of CsPb(Br x I 1− x ) 3 .

Kesterite Cu 2 ZnSnS x Se 4− x (CZTSSe) is among the most promising inorganic Earth‐abundant thin‐film photovoltaic technologies, although currently, the larger voltage deficit compared with more mature chalcogenide technologies is hampering solar‐to‐electricity conversion efficiency progress in these materials. Most of the latest reports agree on the CZTSSe defect structure as the main limitation for the open‐circuit voltage. Small atom doping is suggested as an interesting strategy to reduce the concentration of defects without affecting secondary phase formation. Herein, an innovative approach based on the introduction of LiAlH 4 and its further decomposition during the selenization process of CZTSe precursors, as a pathway for hydrogen and lithium/alkali transient doping, is explored. This process shows a strong beneficial influence on the crystal growth and solar cell device performance, especially with a significant improvement in V oc and fill factor. A reduction of nonradiative recombination and a remarkable fourfold increase in the carrier lifetime correlating with the reduction of the open‐circuit voltage ( V oc ) deficit below 330 mV is demonstrated. A mechanism on how small atoms (Li and H) interact to reduce the concentration of Sn Zn recombination centers while keeping doping relatively unchanged is proposed, opening fundamental perspectives for the simple and universal transient doping of thin‐film chalcogenide compounds.

Copper chalcogenide nanocrystals find applications in photovoltaic inks, bio labels, and thermoelectric materials. We reveal insights in the nucleation and growth during synthesis of anisotropic Cu2ZnSnS4 nanocrystals by simultaneously performing in situ X-ray absorption spectroscopy (XAS) and small-angle X-ray scattering (SAXS). Real-time XAFS reveals that upon thiol injection into the reaction flask, a key copper thiolate intermediate species is formed within fractions of seconds, which decomposes further within a narrow temperature and time window to form copper sulfide nanocrystals. These nanocrystals convert into Cu2ZnSnS4 nanorods by sequentially incorporating Sn and Zn. Real-time SAXS and ex situ TEM of aliquots corroborate these findings. Our work demonstrates how combined in situ X-ray absorption and small-angle X-ray scattering enables the understanding of mechanistic pathways in colloidal nanocrystal formation.

Optical in situ monitoring tracks crystallization and optoelectronic properties of halide perovskites during growth in a glovebox environment.

The structure stability and optoelectronic properties of co-evaporated CsPbI3 thin films with a wide range of [CsI]/[PbI2] compositional ratios are investigated. We find that for CsI-rich growth conditions, CsPbI3 can be synthesized directly at low temperature into the distorted perovskite  CsPbI3 phase with Schottky-type defects and without detectable secondary phases. In contrast, PbI2-rich growth conditions are found to lead to the non-perovskite phase. Photoluminescence spectroscopy and optical pump-THz probe measurements show carrier lifetimes larger than 75 ns and charge carrier (sum) mobilities larger 60 cm/Vs for the -phase, indicating their suitability for high efficiency solar cells. Building on these results pi-n type solar cells with a maximum efficiency exceeding 12 % and high shelf stability of more than 1200 h are demonstrated.

The incorporation of strontium into perovskite solar cells spontaneously modifies the surface increasing the Voc by reducing the non-radiative losses.

The structural phases and optoelectronic properties of coevaporated CsPbI3 thin films with a wide range of [CsI]/[PbI2] compositional ratios are investigated using high throughput experimentation and gradient samples. It is found that for CsI‐rich growth conditions, CsPbI3 can be synthesized directly at low temperature into the distorted perovskite γ‐CsPbI3 phase without detectable secondary phases. In contrast, PbI2‐rich growth conditions are found to lead to the non‐perovskite δ‐phase. Photoluminescence spectroscopy and optical‐pump THz‐probe mapping show carrier lifetimes larger than 75 ns and charge carrier (sum) mobilities larger than 60 cm2 V−1 s−1 for the γ‐phase, indicating their suitability for high efficiency solar cells. The dependence of the carrier mobilities and luminescence peak energy on the Cs‐content in the films indicates the presence of Schottky defect pairs, which may cause the stabilization of the γ‐phase. Building on these results, p–i–n type solar cells with a maximum efficiency exceeding 12% and high shelf stability of more than 1200 h are demonstrated, which in the future could still be significantly improved, judging on their bulk optoelectronic properties.