Lights and Shadows of DMSO as Solvent for Tin Halide Perovskites

In 2020 dimethyl sulfoxide DMSO , the ever present solvent for tin halide perovskites, was identified as an oxidant for SnII. Nonetheless, alternatives are lacking and few efforts have been devoted to replacing it. To understand this trend it is indispensable to learn the importance of DMSO on the development of tin halide perovskites. Its unique properties have allowed processing compact thin films to be integrated into tin perovskite solar cells. Creative approaches for controlling the perovskite crystallization or increasing its stability to oxidation have been developed relying on DMSO based inks. However, increasingly sophisticated strategies appear to lead the field to a plateau of power conversion efficiency in the range of 10 15 amp; 8201; . And, while DMSO based formulations have performed in encouraging means so far, we should also start considering their potential limitations. In this concept article, we discuss the benefits and limitations of DMSO based tin perovskite processin

Challenges and strategies toward long term stability of lead free tin based perovskite solar cells

Due to their outstanding optoelectronic properties, lead based halide perovskite materials have been applied as efficient photoactive materials in solution processed solar cells. Current record efficiencies offer the promise to surpass those of silicon solar cells. However, uncertainty about the potential toxicity of lead based halide perovskite materials and their facile dissolution in water requires a search for new alternative perovskite like materials. Thanks to the foresight of scientists and their experience in lead based halide perovskite preparation, remarkable results have been obtained in a short period of time using lead free perovskite compositions. However, the lower solar to energy conversion efficiency and long term stability issues are serious drawbacks that hinder the potential progression of these materials. Here, we review and analyse strategies in the literature and the most promising solutions to identify the factors that limit the power conversion efficiency and long term stability of lead free tin based perovskite solar cells. In the light of the current state of the art, we offer perspectives for further developing these promising material

Pyridine Controlled Tin Perovskite Crystallization

Controlling the crystallization of perovskite in a thin film is essential in making solar cells. Processing tin based perovskite films from solution is challenging because of the uncontrollable faster crystallization of tin than the most used lead perovskite. The best performing devices are prepared by depositing perovskite from dimethyl sulfoxide because it slows down the assembly of the tin iodine network that forms perovskite. However, while dimethyl sulfoxide seems the best solution to control the crystallization, it oxidizes tin during processing. This work demonstrates that 4 tert butyl pyridine can replace dimethyl sulfoxide to control the crystallization without oxidizing tin. We show that tin perovskite films deposited from pyridine have a 1 order of magnitude lower defect density, which promotes charge mobility and photovoltaic performanc

An open-access database and analysis tool for perovskite solar cells based on the FAIR data principles

Large datasets are now ubiquitous as technology enables higher-throughput experiments, but rarely can a research field truly benefit from the research data generated due to inconsistent formatting, undocumented storage or improper dissemination. Here we extract all the meaningful device data from peer-reviewed papers on metal-halide perovskite solar cells published so far and make them available in a database. We collect data from over 42, 400 photovoltaic devices with up to 100 parameters per device. We then develop open-source and accessible procedures to analyse the data, providing examples of insights that can be gleaned from the analysis of a large dataset. The database, graphics and analysis tools are made available to the community and will continue to evolve as an open-source initiative. This approach of extensively capturing the progress of an entire field, including sorting, interactive exploration and graphical representation of the data, will be applicable to many fields in materials science, engineering and biosciences. © 2021, The Author(s)

Solvents for Processing Stable Tin Halide Perovskites

Tin is one of the most promising alternatives to lead to make lead free halide perovskites for optoelectronics. However, the stability of tin based perovskites is hindered by the oxidation of Sn II to Sn IV . Recent works established that dimethyl sulfoxide, which is one of the best performing solvents for processing perovskite, is the primary source of tin oxidation. The quest for a stable solvent could be a game changer in the stability of tin based perovskites. Starting from a database of over 2000 solvents, we identified a series of 12 new solvents suitable for the processing of formamidinium tin iodide perovskite FASnI3 by investigating 1 the solubility of the precursor chemicals FAI and SnI2, 2 the thermal stability of the precursor solution, and 3 the possibility of forming perovskite. Finally, we demonstrate a new solvent system to produce solar cells outperforming those based on DMSO. Our work provides guidelines for further identification of new solvents or solvent mixtures for preparing stable tin based perovskite

Fluoride Chemistry in Tin Halide Perovskites

Tin is the frontrunner for substituting toxic lead in perovskite solar cells. However, tin suffers the detrimental oxidation of SnII to SnIV. Most of reported strategies employ SnF2 in the perovskite precursor solution to prevent SnIV formation. Nevertheless, the working mechanism of this additive remains debated. To further elucidate it, we investigate the fluoride chemistry in tin halide perovskites by complementary analytical tools. NMR analysis of the precursor solution discloses a strong preferential affinity of fluoride anions for SnIV over SnII, selectively complexing it as SnF4. Hard X ray photoelectron spectroscopy on films shows the lower tendency of SnF4 than SnI4 to get included in the perovskite structure, hence preventing the inclusion of SnIV in the film. Finally, small angle X ray scattering reveals the strong influence of fluoride on the colloidal chemistry of precursor dispersions, directly affecting perovskite crystallizatio