Search

Tin halide perovskite solar cells (Sn-PSCs) have emerged as promising alternatives to their lead-based counterparts. However, their potential for commercialization is threatened by their inherent stability issues and lower efficiencies that have not yet matched those of established technologies. Therefore, in this work we strategically designed and synthesized two novel organic compounds, referred to as OM4 and OM6, which have been successfully incorporated as additives into pure FASnI3 PSCs enhancing the crystal properties and simultaneously acting as protective and passivating agents. Through a systematic exploration of chemical interactions, OM4 and OM6 demonstrated a remarkable ability to improve film morphology and optical properties. Consequently, both additives significantly contributed to the enhancement of the overall device performances and exhibited impressive stabilities in the ambient atmosphere, which is attributed to their hydrophobic nature. Notably, the unencapsulated devices incorporating OM4 and OM6 retained over 80% and 90% of their initial power conversion efficiency (PCE) after 250 hours in the ambient atmosphere at RH = 30%, respectively; in contrast, the devices without any of the organic additives suffered complete degradation after 72 hours under the same conditions. As a result, this work opens new possibilities in the rational design and development of organic additives capable of mitigating the instability and low-performance issues commonly associated with Sn-PSCs. [ABSTRACT FROM AUTHOR]

The choice of structure directing agents (SDAs) in zeolite synthesis significantly impacts the arrangement of active sites, thereby influencing the stabilization of reaction intermediates with profound implications for catalytic applications. Therefore, understanding the distribution of SDAs along with the substitution of heteroatoms for silicon in zeolites is imperative for tailoring optimized materials for specific applications. This study is centered on the synthesis of all-silica RTH type zeolites in the presence of fluoride, utilizing triisopropyl(methyl)phosphonium as the organic SDA (OSDA). Zeolites produced under varying conditions of time and temperature exhibit differences in their X-ray diffractograms, indicating the presence of two distinct crystalline phases. The 19F NMR spectra confirm the presence of fluoride within the small rth cage and exhibit two distinct signals depending on the sample. The 29Si NMR spectra reveal the existence of penta-coordinated F-SiO4 species, resulting in sixteen non-equivalent Si sites. Through ab initio DFT methods, the stabilization energy and 29Si chemical shielding of several models featuring F-SiO4 situated at all crystallographic sites were computed. Comparison with experimental results enabled the identification of the framework position where the five-coordinate silicon is located, which differs between the two crystalline phases of the as-synthesized RTH zeolites. Consequently, the placement of fluoride in either of these two sites within the RTH zeolite can be controlled during the synthesis. It is expected that this methodology can be extended to manipulate the position of trivalent atoms (e.g., Al3+ or B3+), which can affect the catalytic properties of the RTH zeolite. [ABSTRACT FROM AUTHOR]