Chalcogenide perovskites have recently emerged into the spotlight as highly robust, earth abundant, and nontoxic candidates for various energy conversion applications, not least photovoltaics (PV). Now, a serious effort is required to determine if they can emulate the PV performance of the better‐known, part‐organic halide perovskites, in applications such as tandem solar cells. This review summarizes the surprisingly large body of literature pertaining to chalcogenide perovskites, which have been investigated for many years despite only recently being considered for applications. The confusing variety of claims coming from computational materials discovery is clarified, and it is specified which chalcogenide perovskites actually exist and should form the focus of experimental work. The highly interesting optoelectronic and transport properties of the known materials at their current stage of development are summarized, which makes a clear case for investigating them further. The existing synthesis literature is collated, which provides some important and possibly unnoticed clues to experimentalists grappling with these somewhat challenging materials. The authors hope that the highlighting of this information will facilitate further exciting studies, better approaches, and new progress for chalcogenide perovskites.

Tandem solar cells based on hybrid organic−inorganic metal halide perovskites have reached efficiencies up to 28%, but major concerns for long-term stability and the presence of Pb have raised interest in searching for fully earth-abundant, intrinsic chemically stable, and nontoxic alternatives. With a direct band gap around 1.8 eV and stability in air up to at least 500 °C, BaZrS 3 is a promising candidate. This work presents the first approach of synthesizing a thin film of such compound by sputtering at ambient temperature with a subsequent rapid thermal process. Despite the short fabrication time, the width of the XRD diffraction peaks and the energy and distribution of the photoluminescence response show comparable crystalline quality to that from bulk synthesis methods. Good crystallization required around 900 °C. Such a high temperature could be incompatible with fabrication of tandem solar cells.

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In this study, we investigate the metallization‒induced recombination losses of high efficiency bifacial n‒type and p‒type crystalline Si solar cells. From the experimental data, we found that the most efficiency limiting parameter by the screen‒printed metallization is the open‒circuit voltage (VOC) of the cells. We investigated the mechanism responsible for this loss by varying the metallization fraction on either side of the cell and determined the local enhancement in the dark saturation current density beneath the metal contacts (J0(met)). Under optimum fabrication conditions, the J0(met) at metal‒p+ (boron) emitter interfaces was found to be significantly higher compared with the values obtained for metal‒n+ emitters. A two‒dimensional simulation model was used to get further insight into the recombination mechanism leading to these VOC losses. The model assumes that metal contacts penetrate (or etch) into the diffused region following the firing process and depassivate the interface. Applying this model to our n‒type solar cells with a boron p+ emitter, we demonstrated that the simple loss of passivated area beneath the metal contact cannot explain the degradation observed in the VOC of the cell without considering a significant etching or metal penetration into the emitter region. Copyright © 2014 John Wiley & Sons, Ltd.

Chalcogenide perovskites are being considered for various energy conversion applications, not least photovoltaics. BaZrS 3 stands out for its highly stable, earth-abundant, and nontoxic nature. It exhibits a very strong light−matter interaction and an ideal band gap for a top subcell in a two-junction photovoltaic device. So far, thin-film synthesisnecessary for proper optoelectronic characterization as well as device integrationremains underdeveloped. Sputtering has been considered, among others, but the need for an annealing step of at least 900 °C has been a cause for concern: such a high temperature could lead to damaging the bottom layers of prospective tandem devices. Still, a solid-state fabrication route has already demonstrated that BaZrS 3 can form at much lower temperatures if excess S is present. In this work, sputtered Ba−Zr precursors capped by SnS are sulfurized at under 600 °C for 20 min. Although some Sn is still present at the surface after sulfurization, the resulting crystalline quality is comparable to samples synthesized at much higher temperatures. The results are rationalized, and the effect of key process variables is examined. This study represents the first successful synthesis of BaZrS 3 perovskite that is compatible with conductive substratesan important step forward for device integration.

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