Octahedral Tilt Engineering: Atomic-Level Picture of Stabilized α-FAPbI3

Tiarnan Doherty^a, Satyawan Nagane^a, Dominik Kubicki^a^,^b, Young-Kwang Jung^c, Duncan Johnstone^d, Affan Iqbal^a^,^e, Dengyang Guo^a^,^e, Kyle Frohna^a, Mohsen Danaie^f^,^g, Elizabeth Tennyson^a, Stuart Macpherson^a, Anna Abfalterer^a, Miguel Anaya^a^,^e, Yu-Hsien Chiang^a, Phillip Crout^d, Francesco Simone Ruggeri^h, Sean Collinsⁱ, Clare Grey^b, Aron Walsh^c^,^j, Paul Midgley^d, Samuel Stranks^a^,^e

^aDepartment of Physics, Cavendish Laboratory, University of Cambridge; Cambridge, UK

^bYusuf Hamied Department of Chemistry, University of Cambridge; Lensfield Road, Cambridge, UK

^cDepartment of Materials Science and Engineering, Yonsei University; Seoul, Korea

^dDepartment of Materials Science and Metallurgy, University of Cambridge; Cambridge, UK

^eDepartment of Chemical Engineering and Biotechnology, University of Cambridge; Cambridge, UK

^fElectron Physical Science Imaging Centre, Diamond Light Source Ltd; Didcot, UK

^gDepartment of Materials, University of Oxford; Oxford, UK

^hLaboratory of Organic and Physical Chemistry, Wageningen University and Research, the Netherlands

ⁱSchool of Chemical and Process Engineering & School of Chemistry, University of Leeds; Leeds, UK

^jDepartment of Materials, Imperial College London; London, UK

Proceedings of Online Conference on Atomic-level Characterisation of Hybrid Perovskites (HPATOM2)

Online, Spain, 2022 February 2nd - 3rd

Organizers: Michael Hope and Eve Mozur

Invited Speaker, Dominik Kubicki, presentation 020
DOI: https://doi.org/10.29363/nanoge.hpatom.2022.020
Publication date: 30th October 2021

There is currently substantial interest in stabilizing the simple ternary FAPbI₃ perovskite because of its near-optimal band gap and superior thermal stability compared to methylammonium-based materials.¹ The key challenge of FAPbI₃ is the thermodynamic instability of the polymorph required for efficient light harvesting. Without additives, the black photoactive α-polymorph is only stable above ca. 160°C. At room temperature, it is metastable and rapidly transitions to the non-perovskite yellow polymorph. The stabilization of the black polymorph at room temperature can be achieved, for example, by adding a small amount of the pernicious MA through use of methylammonium chloride (in conjunction with formamidinium formate),² methylammonium thiocyanate,³ or methylammonium formate.⁴ We have developed a new stabilization strategy which does not involve the addition of MA.⁵ Instead, it uses a surface-templating agent (EDTA) which modifies the material without incorporating into the structure. We use a combination of scanning electron diffraction (SED) and nuclear magnetic resonance spectroscopies (NMR, NQR) to identify the atomic-level mechanism of action of EDTA in this role. We find that it templates the structure by inducing a small octahedral tilt, only resolvable with local characterization techniques, and imparts remarkable phase stability by arresting transitions to low-dimensional polymorphs. This octahedral tilt engineering strategy is remarkably universal, and we show that it is the intrinsic stabilization mechanism in the state-of-the-art FA-rich mixed-cation materials.

References:

[1] Huang, Y.; Lei, X.; He, T.; Jiang, Y.; Yuan, M. Recent Progress on Formamidinium-Dominated Perovskite Photovoltaics. Adv. Energy Mater. 2100690

[2] Jeong, J.; Kim, M.; Seo, J.; Lu, H.; Ahlawat, P.; Mishra, A.; Yang, Y.; Hope, M. A.; Eickemeyer, F. T.; Kim, M.; Yoon, Y. J.; Choi, I. W.; Darwich, B. P.; Choi, S. J.; Jo, Y.; Lee, J. H.; Walker, B.; Zakeeruddin, S. M.; Emsley, L.; Rothlisberger, U.; Hagfeldt, A.; Kim, D. S.; Grätzel, M.; Kim, J. Y. Pseudo-Halide Anion Engineering for α-FAPbI3 Perovskite Solar Cells. Nature 2021, 592 (7854), 381–385

[3] Lu, H.; Liu, Y.; Ahlawat, P.; Mishra, A.; Tress, W. R.; Eickemeyer, F. T.; Yang, Y.; Fu, F.; Wang, Z.; Avalos, C. E.; Carlsen, B. I.; Agarwalla, A.; Zhang, X.; Li, X.; Zhan, Y.; Zakeeruddin, S. M.; Emsley, L.; Rothlisberger, U.; Zheng, L.; Hagfeldt, A.; Grätzel, M. Vapor-Assisted Deposition of Highly Efficient, Stable Black-Phase FAPbI3 Perovskite Solar Cells. Science 2020, 370 (6512)

[4] Hui, W.; Chao, L.; Lu, H.; Xia, F.; Wei, Q.; Su, Z.; Niu, T.; Tao, L.; Du, B.; Li, D.; Wang, Y.; Dong, H.; Zuo, S.; Li, B.; Shi, W.; Ran, X.; Li, P.; Zhang, H.; Wu, Z.; Ran, C.; Song, L.; Xing, G.; Gao, X.; Zhang, J.; Xia, Y.; Chen, Y.; Huang, W. Stabilizing Black-Phase Formamidinium Perovskite Formation at Room Temperature and High Humidity. Science 2021, 371 (6536), 1359–1364

[5] Doherty, T.; Nagane, S.; Kubicki, D. J.; Jung, Y. K.; Johnstone, D. N.; Iqbal, A.; Guo, D.; Frohna, K.; Danaie, M.; Tennyson, E. M.; MacPherson, S.; Abfalterer, A.; Anaya, M.; Chiang, Y.-H.; Crout, P.; Ruggeri, F. S.; Collins, S.; Grey, C. P.; Walsh, A.; Midgley, P.; Stranks, S. D. Stabilized Tilted-Octahedra Halide Perovskites Inhibit Local Formation of Performance-Limiting Phases. Science 2021, 374 (6575), 1598–1605

Acknowledgements:

The authors acknowledge Julia Parker and Paul Quinn for support during experiments on the I14 beamline at Diamond Light Source. Funding: T.A.S.D. (National University of Ireland Travelling Studentship); S.N. (Royal Society and SERB for funding a Newton International Fellowship). S.D.S. (Royal Society and Tata Group (UF150033); ERC Horizon 2020 HYPERION - grant agreement no. 756962); P.A.M. (EPSRC, EP/R008779/1); EPSRC (EP/R023980/1). K.F. (George and Lilian Schiff Studentship, Winton Studentship, EPSRC studentship, Cambridge Trust Scholarship, and Robert Gardiner Scholarship). D.J.K., E.M.T., and M.A. (MSCA, grants 841136, 841265, 841386, respectively) - EU Horizon 2020. A.N.I. (British Spanish Society and the Sir Richard Stapley Educational Trust); S.M. (EPSRC studentship). A.A. (Royal Society). S.M.C (University Academic Fellowship at the University of Leeds); P.C. (EPSRC studentship). C.P.G (EU ERC Advanced Fellowship DLV-835073); National Research Foundation of Korea (grant 2018R1C1B6008728). EU Horizon 2020 INFRAIA (ESTEEM3, 823717); Diamond Light Source - beamline I14 (proposal sp20420) and EPSIC (Instrument E02, proposal MG24111); The work used the ARCHER UK National Supercomputing Service via our membership of the UK's HEC Materials Chemistry Consortium - EPSRC (EP/L000202).

nanoGe is a prestigious brand of successful science conferences that are developed along the year in different areas of the world since 2009. Our worldwide conferences cover cutting-edge materials topics like perovskite solar cells, photovoltaics, optoelectronics, solar fuel conversion, surface science, catalysis and two-dimensional materials, among many others.

MATSUS

Previously nanoGe Spring Meeting (NSM) and nanoGe Fall Meeting (NFM), MATSUS is a multiple symposia conference focused on a broad set of topics of advanced materials preparation, their fundamental properties, and their applications, in fields such as renewable energy, photovoltaics, lighting, semiconductor quantum dots, 2-D materials synthesis, charge carriers dynamics, microscopy and spectroscopy semiconductors fundamentals, etc.

International Conference on Hybrid and Organic Photovoltaics

International Conference on Hybrid and Organic Photovoltaics (HOPV) is celebrated yearly in May. The main topics are the development, function and modeling of materials and devices for hybrid and organic solar cells. The field is now dominated by perovskite solar cells but also other hybrid technologies, as organic solar cells, quantum dot solar cells, and dye-sensitized solar cells and their integration into devices for photoelectrochemical solar fuel production.

Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics

The main topics of the Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics (IPEROP) are discussed every year in Asia-Pacific for gathering the recent advances in the fields of material preparation, modeling and fabrication of perovskite and hybrid and organic materials. Photovoltaic devices are analyzed from fundamental physics and materials properties to a broad set of applications. The conference also covers the developments of perovskite optoelectronics, including light-emitting diodes, lasers, optical devices, nanophotonics, nonlinear optical properties, colloidal nanostructures, photophysics and light-matter coupling.

International Conference on Perovskite Thin Film Photovoltaics Perovskite Photonics and Optoelectronics

The International Conference on Perovskite Thin Film Photovoltaics Perovskite Photonics and Optoelectronics (NIPHO) is the best place to hear the latest developments in perovskite solar cells as well as on recent advances in the fields of perovskite light-emitting diodes, lasers, optical devices, nanophotonics, nonlinear optical properties, colloidal nanostructures, photophysics and light-matter coupling.