A comprehensive study of Lanthanides based Halide Double Perovskites A₂MTlX₆ for high frequency optical and thermoelectric applications

A comprehensive study of Lanthanides based Halide Double Perovskites A₂MTlX₆ for high frequency optical and thermoelectric applications | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article A comprehensive study of Lanthanides based Halide Double Perovskites A₂MTlX₆ for high frequency optical and thermoelectric applications Muhammad Amjad, G. Murtaza, Rajwali Khan, Aarfa A. Yagob, Khamael M. Abualnaja, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7585186/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract The design of stable, nontoxic, and efficient halide double perovskites has emerged as a strategic pathway toward next-generation optoelectronic and energy conversion devices. In this work, we present a comprehensive first-principles investigation of A₂MTlX₆ (A = K, Rb, Cs; M = Sc, Y, La; X = Cl, Br, I) compounds using the FP-LAPW method with local orbitals, incorporating PBEsol-GGA and the TB-mBJ exchange–correlation schemes for accurate property prediction. Structural stability was confirmed through formation energies, tolerance and octahedral factors, and Born stability criteria. Elastic constant analysis revealed predominantly ductile behavior, with only Cs₂ScTlCl₆ and Rb₂LaTlCl₆ showing brittleness, while high melting points and moderate anisotropy underline their robustness. Electronic calculations demonstrate wide band gaps (2.79–4.66 eV), with most compounds exhibiting direct transitions suitable for visible–UV absorption. Optical spectra reveal transparency in the low-energy regime and strong absorption and conductivity peaks in the visible–ultraviolet range, suggesting excellent light-harvesting potential. Among them, K₂ScTlI₆, Rb₂ScTlI₆, Cs₂ScTlI₆, and Rb₂LaTlI₆ emerge as particularly promising candidates for photovoltaic and optoelectronic applications. Thermoelectric properties, evaluated via Seebeck coefficient, electrical and thermal conductivities, and power factor, indicate ultralow lattice thermal conductivity from Slack’s model and figure of merit (ZT) values of 0.66–0.85, approaching the benchmark for practical devices. The synergistic combination of optical absorption, mechanical resilience, and thermoelectric efficiency positions A₂MTlX₆ halide double perovskites as highly versatile and sustainable materials for future renewable energy technologies. Physical sciences/Energy science and technology Physical sciences/Materials science Physical sciences/Physics Lanthanides-based double perovskites FP-LAPW + lo IR-Elast Electronic structure Optical properties Lattice thermal conductivity ZT Full Text Additional Declarations No competing interests reported. Supplementary Files SupplementryMaterials.docx Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7585186","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":515738336,"identity":"525c250a-fed2-4ed9-b748-cb22c69b7ca1","order_by":0,"name":"Muhammad Amjad","email":"","orcid":"","institution":"Islamia College Peshawar","correspondingAuthor":false,"prefix":"","firstName":"Muhammad","middleName":"","lastName":"Amjad","suffix":""},{"id":515738337,"identity":"aa7ea66d-7fb8-440b-bcd9-fcce0464a6ac","order_by":1,"name":"G. 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applications","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":true,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Lanthanides-based double perovskites, FP-LAPW + lo, IR-Elast, Electronic structure, Optical properties, Lattice thermal conductivity, ZT","lastPublishedDoi":"10.21203/rs.3.rs-7585186/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7585186/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe design of stable, nontoxic, and efficient halide double perovskites has emerged as a strategic pathway toward next-generation optoelectronic and energy conversion devices. In this work, we present a comprehensive first-principles investigation of A₂MTlX₆ (A\u0026thinsp;=\u0026thinsp;K, Rb, Cs; M\u0026thinsp;=\u0026thinsp;Sc, Y, La; X\u0026thinsp;=\u0026thinsp;Cl, Br, I) compounds using the FP-LAPW method with local orbitals, incorporating PBEsol-GGA and the TB-mBJ exchange\u0026ndash;correlation schemes for accurate property prediction. Structural stability was confirmed through formation energies, tolerance and octahedral factors, and Born stability criteria. Elastic constant analysis revealed predominantly ductile behavior, with only Cs₂ScTlCl₆ and Rb₂LaTlCl₆ showing brittleness, while high melting points and moderate anisotropy underline their robustness. Electronic calculations demonstrate wide band gaps (2.79\u0026ndash;4.66 eV), with most compounds exhibiting direct transitions suitable for visible\u0026ndash;UV absorption. Optical spectra reveal transparency in the low-energy regime and strong absorption and conductivity peaks in the visible\u0026ndash;ultraviolet range, suggesting excellent light-harvesting potential. Among them, K₂ScTlI₆, Rb₂ScTlI₆, Cs₂ScTlI₆, and Rb₂LaTlI₆ emerge as particularly promising candidates for photovoltaic and optoelectronic applications. Thermoelectric properties, evaluated via Seebeck coefficient, electrical and thermal conductivities, and power factor, indicate ultralow lattice thermal conductivity from Slack\u0026rsquo;s model and figure of merit (ZT) values of 0.66\u0026ndash;0.85, approaching the benchmark for practical devices. The synergistic combination of optical absorption, mechanical resilience, and thermoelectric efficiency positions A₂MTlX₆ halide double perovskites as highly versatile and sustainable materials for future renewable energy technologies.\u003c/p\u003e","manuscriptTitle":"A comprehensive study of Lanthanides based Halide Double Perovskites A₂MTlX₆ for high frequency optical and thermoelectric applications","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-09-24 08:53:01","doi":"10.21203/rs.3.rs-7585186/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"3a925a6a-4be4-4ecb-b618-64ff69ea4fb1","owner":[],"postedDate":"September 24th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":54786331,"name":"Physical sciences/Energy science and technology"},{"id":54786332,"name":"Physical sciences/Materials science"},{"id":54786333,"name":"Physical sciences/Physics"}],"tags":[],"updatedAt":"2025-10-13T05:54:18+00:00","versionOfRecord":[],"versionCreatedAt":"2025-09-24 08:53:01","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7585186","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7585186","identity":"rs-7585186","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}