{"id":8985,"date":"2020-09-30T15:16:24","date_gmt":"2020-09-30T18:16:24","guid":{"rendered":"https:\/\/www.sbpmat.org.br\/?p=8985"},"modified":"2020-10-31T16:59:54","modified_gmt":"2020-10-31T19:59:54","slug":"artigo-em-destaque-perovskitas-aditivadas-para-celulas-solares-mais-estaveis","status":"publish","type":"post","link":"https:\/\/www.sbpmat.org.br\/en\/artigo-em-destaque-perovskitas-aditivadas-para-celulas-solares-mais-estaveis\/","title":{"rendered":"Featured paper: Additivated perovskites for more stable solar cells."},"content":{"rendered":"

[Paper:\u00a0Effect of the incorporation of poly(ethylene oxide) copolymer on the stability of perovskite solar cells.<\/strong><\/em>\u00a0Jeann Carlos da Silva, Francineide Lopes de Ara\u00fajo, Rodrigo Szostak, Paulo Ernesto Marchezi, Raphael Fernando Moral, Jilian Nei de Freitas\u00a0 and\u00a0 Ana Fl\u00e1via Nogueira. J. Mater. Chem. C, 2020,8, 9697-9706].<\/p>\n

\""Sandwich"
“Sandwich” of materials that form the perovskite solar cell developed by the Brazilian team.<\/figcaption><\/figure>\n

Thanks to the contributions of research groups from different countries, perovskite-based solar cells have quickly become competitive in terms of energy conversion efficiency \u2013 the percentage of solar energy that is converted into electrical energy \u2013 reaching values above 25%. Unfortunately, the good efficiency achieved for these solar cells does not remain throughout their use, mainly because of the instability of their active layer. Composed of materials from the perovskite family, this layer of the sandwich-like solar cell is responsible for absorbing light. Due to moisture, as well as light itself, perovskite degrades and threatens the life cycle of a solar cell.<\/p>\n

The problem has been the focus of many researchers in the area, among them,\u00a0those from the Laboratory of Nanotechnology and Solar Energy (LNES) at Unicamp (Brazil), led by Professor Ana Fl\u00e1via Nogueira. In recently reported research in the Journal of Materials Chemistry C (impact factor 7.059), LNES members were able to produce more stable perovskite films\u00a0which allowed manufacturing solar cells with lower efficiency losses over time.<\/p>\n

\"The
The addition of copolymer P(EO\/EP) improved the stability of MAPbI3 perovskite.<\/figcaption><\/figure>\n

The strategy adopted was to add to the perovskite a compound that gives it stability without affecting its crystalline structure, from which\u00a0important properties emerge for solar cell performance. The chosen additive, a copolymer (polymer formed by two different monomers), was added in different concentrations to a solution of lead iodide and methylammonium iodide, which, when crystallized, formed a modified and more stable perovskite film.<\/p>\n

The researchers used the spin coating technique to prepare filmes of pure perovskite and \u201cadditivated\u201d perovskite. In a material degradation test, the authors exposed the samples to ambient light and humidity for nine days and observed their degradation, which was visible to the naked eye by the yellowing of the films, whose original color is almost black. In the samples with additive, the degradation was delayed by a few days when compared to the pure perovskite samples.<\/p>\n

Another test carried out by the team showed the films’ ability to regenerate after an initial degradation caused by exposure to a humidifier. The samples with the additive not only degraded less, but also spontaneously regenerated, almost entirely, thirty seconds after removing the moisture source \u2013 a phenomenon known as healing \u2013 as can be seen in this video<\/a>.<\/p>\n

\u201cThis work demonstrated that incorporating a copolymer based on poly(ethylene oxide) to the perovskite layer can delay and, in some cases, even reverse the degradation process of the film with relation to moisture and lighting,\u201d summarizes Jeann Carlos da Silva, co-author of the article.<\/p>\n

\"box_en\"To study in detail the structure and composition of the films, the authors used a series of characterization techniques, including an X-ray diffraction technique (in situ GWAXS), available at the Brazilian National Synchrotron Light Laboratory (LNLS), which allowed to monitor the manufacturing process of the films. Based on the set of characterization results, the authors were able to explain the mechanism that generates the protective effect in perovskite films with additives. According to them, the effect occurs mainly due to the interaction performed by the copolymer, through hydrogen bonds, with the methylammonium cation of the perovskite.\u00a0 In films without the additive, light and moisture cause part of the methylammonium to shift into the gas state and then leave the perovskite structure, generating the degradation, which is partially irreversible. In the films with the additive, the copolymer retains the methylammonium, which generates films that are more stable and have greater regenerative capacity.<\/p>\n

\u201cThis study also allowed to investigate the crystallization dynamics of the perovskite\u00a0containing\u00a0the copolymer, as well as to understand the formation mechanisms of perovskite\/copolymer in humidity and lighting conditions,\u201d highlights Francineide Lopes de Ara\u00fajo, co-author of the article. \u201cIn addition, through characterization techniques such as in situ <\/em>X-ray diffraction, the study explores an important area in order to understand the material, offering an important contribution to the scientific community and opening new investigation perspectives for the application of polymers in the process of forming and manufacturing perovskite solar cells,\u201d she adds.<\/p>\n

Finally, the scientific team manufactured solar cells using perovskite films with and without additives as active layer, and compared their energy conversion efficiency. Initially, the presence of the copolymer decreased the efficiency of the devices, since, as it is an insulating material, it impairs the transfer of electrical charges. However, in the stability tests, when the devices were exposed to humidity and light for twenty days, the perovskite cells with additives performed better.<\/p>\n

In numbers: while pure perovskite solar cells started at 17% efficiency and maintained 47% of that value at the end of the test, perovskite devices containing 1.5 mg mL-1% copolymer had an initial efficiency of around 15 %, but retained 68% of efficiency after the 20 days of testing.<\/p>\n

\u201cUnfortunately, the problem of stability of perovskite solar cells could not be definitively solved through this research, however, an important way to protect the material was explored, mainly against aggressive exposure to moisture and light, which in the future can be combined with other protection mechanisms,\u201d summarizes Jeann Carlos da Silva. \u201cThe research also reinforces the feasibility of incorporating extrinsic compounds to perovskite as protective agents,\u201d he adds.<\/p>\n

This study began at LNES in 2016, in the master’s\u00a0research\u00a0of Jeann Carlos da Silva, shortly after the development, in that same laboratory, of the first perovskite solar cell prototype in Brazil. The research was completed with the collaboration of the postdoctoral\u00a0fellow Francineide Lopes de Ara\u00fajo and other members and former members of the group, always under the guidance of Professor Ana Fl\u00e1via.<\/p>\n

The study was funded by Brazilian agencies FAPESP, CNPq and CAPES, and is the subject of the project \u201cPerovskite Solar Cells for Artificial Photosynthesis\u201d of the Center for Innovation on New Energies (CINE) with support from Shell and Fapesp.<\/p>\n

\"Authors
Authors of the paper. From the left: Jeann Carlos da Silva, Francineide Lopes de Ara\u00fajo, Rodrigo Szostak, Paulo Ernesto Marchezi, Raphael Fernando Moral, Jilian Nei de Freitas and Ana Fl\u00e1via Nogueira.<\/figcaption><\/figure><\/p>","protected":false},"excerpt":{"rendered":"

[Paper:\u00a0Effect of the incorporation of poly(ethylene oxide) copolymer on the stability of perovskite solar cells.\u00a0Jeann Carlos da Silva, Francineide Lopes de Ara\u00fajo, Rodrigo Szostak, Paulo Ernesto Marchezi, Raphael Fernando Moral, Jilian Nei de Freitas\u00a0 and\u00a0 Ana Fl\u00e1via Nogueira. J. Mater. Chem. C, 2020,8, 9697-9706]. Thanks to the contributions of research groups from different countries, perovskite-based […]<\/p>\n","protected":false},"author":4,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[6],"tags":[1061,876,2003,2002,878,389,223],"_links":{"self":[{"href":"https:\/\/www.sbpmat.org.br\/en\/wp-json\/wp\/v2\/posts\/8985"}],"collection":[{"href":"https:\/\/www.sbpmat.org.br\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.sbpmat.org.br\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.sbpmat.org.br\/en\/wp-json\/wp\/v2\/users\/4"}],"replies":[{"embeddable":true,"href":"https:\/\/www.sbpmat.org.br\/en\/wp-json\/wp\/v2\/comments?post=8985"}],"version-history":[{"count":6,"href":"https:\/\/www.sbpmat.org.br\/en\/wp-json\/wp\/v2\/posts\/8985\/revisions"}],"predecessor-version":[{"id":9034,"href":"https:\/\/www.sbpmat.org.br\/en\/wp-json\/wp\/v2\/posts\/8985\/revisions\/9034"}],"wp:attachment":[{"href":"https:\/\/www.sbpmat.org.br\/en\/wp-json\/wp\/v2\/media?parent=8985"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.sbpmat.org.br\/en\/wp-json\/wp\/v2\/categories?post=8985"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.sbpmat.org.br\/en\/wp-json\/wp\/v2\/tags?post=8985"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}