Molecular doping is an of significance approach to reduce defects density of perovskite and to improve interfacial charge extraction in perovskite solar cells. Here, we show a new strategy for chemical doping of perovskite via an organic small molecule, which features a fused tricyclic core, showing strong intermolecular p-Pb 2+ interactions with under-coordinated Pb 2+ in perovskite. This p-Pb 2+ interactions could reduce defects density of the perovskite and suppress the nonradiative recombination, which was also confirmed by the density functional theory calculations. In addition, this doping via p-Pb 2+ interactions could deepen the surface potential and downshift the work function of the doped perovskite film, facilitating the hole extraction to hole transport layer. As a result, the doped device showed high efficiency of 21.41 % with ignorable hysteresis. This strategy of fused tricyclic corebased doping provides a new perspective for the design of new organic materials to improve the device performance.
SnÀ Pb alloyed perovskites have drawn considerable attention because of their appropriate band gap for both single-junction and multi-junction tandem photovoltaics, but the easy-formation of energy disorder still limits their practical applications. Here, we report that the combination of 1-bromo-4-(methylsulfinyl) benzene (BBMS) and SnF 2 greatly reduced the Urbach energy of perovskite films, and largely restrained the oxidation of Sn 2 + . With the help of density functional theory calculations, we clarified the interactions between BBMS and perovskite were responsible for the improvements. As a result, a high efficiency of > 22 % was obtained for the SnÀ Pb alloy-based solar cells treated by BBMS and SnF 2 . More importantly, the BBMS-treated devices demonstrated outstanding stability, retaining 98 % of its original efficiency after heating at 60 °C for 2660 h under N 2 .
Tin−lead (Sn−Pb) alloyed perovskites are promising candidates for next-generation photovoltaics due to their appropriate bandgaps for multijunction tandem solar cells, which can potentially overcome the Shockley-Queisser limit. However, their power conversion efficiency (PCE) and stability are still impeded by the poor absorber quality and defects caused by the oxidation of Sn 2+ . Here, we introduced trimethylsulfoxonium iodide (TMSI) as an additive along with SnF 2 to fabricate Sn−Pb perovskite films with enlarged grains and improved film quality. TMSI restrained the oxidation of Sn 2+ through molecular interactions, reducing the formation of detrimental Sn vacancies. As a result, a highly oriented Sn−Pb alloyed perovskite with a lower defect density was obtained, along with suppressed ion migration. The TMSI-treated Sn−Pb-based devices exhibited a champion PCE of 22.6% and outstanding stability, retaining 83% of their original efficiency after 6000 h of storage under a N 2 atmosphere and maintaining 88% of their initial value after 1200 h of continuous one-sun illumination.
Aiming to regulate the crystallization and reduce defects of perovskite film, an organic small molecule with sulfonyl, 3-ethylbenzo[d]isothiazole 1,1-dioxide (PSAD), is introduced into perovskite precursor solution. A variety of characterizations...
Recently, lead halide perovskites have attracted great attention in photovoltaic field because of high power conversion efficiency. However, the toxicity of lead in perovskite can result in environment issues, which are the major challenge for commercial application. In this context, environmentally friendly lead‐free perovskite alternatives are highly desired. Bearing excellent photophysical and electronic properties, tin‐perovskites (ASnX3) are the most promising alternative. In reality, extensive efforts have been committed to the development of Sn‐based perovskite solar cells. In this review, we summarized the theoretical fundamentals of Sn‐based perovskites, including lattice, phases, molecular orbital, redox property, and defects. Then varieties of tactics to improve devices performance were detailed reviewed. Finally, perspectives on further research directions in improving Sn‐based solar cells performance are presented.
Main observation and conclusion
A general and practical protocol for the construction of diversified sulfur heterocycles has been described through organic electrosynthesis means. In undivided cell, dihydrothiophenes, thiazolines and 1,4‐dithiines could be easily generated from various available β‐ketothioamides under metal‐free and external oxidant‐free conditions. The transformation underwent smoothly under mild conditions and could be easily scaled‐up. Moreover, different sulfur heterocycles were generated through varying solvent and 1,4‐diazabicyclo[2.2.2]octane (DABCO) could enable the hydrogen atom transfer (HAT) process of this transformation.
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