(357a) Solution Deposited Synthesis of Chalcogenide Perovskites at Temperatures below 600°C

I am interested in working on the technical aspects of synthesis and characterization of materials technologies for applications in thin-film photovoltaics, photo-catalysts, batteries, or novel material synthesis. My expertise lies in air-sensitive synthesis of solution-processed thin film solar cells and studying the relationship between synthesis conditions and the material’s chemical and optoelectronic properties through characterization techniques including SEM-EDX, XRD, Raman, photoluminescence, and others.

Research Summary:

Chalcogenide perovskites have recently garnered great interest for photovoltaic applications due to their predicted and experimentally verified high stabilities compared with halide perovskites, while retaining their excellent optoelectronic properties. ¹ One of the greatest challenges with using chalcogenide perovskites for applications in solar cells is that they have historically required high synthesis temperatures. Traditional methods for synthesis of BaZrS₃ include the sulfurization of BaZrO₃ using H₂S or CS₂,^2,3 molecular beam epitaxy,⁴ pulsed laser deposition using a BaZrS₃ target,⁵ co-sputtering of barium and zirconium metals or metal sulfides,⁶ and solid-state synthesis using metal and metal chalcogenide powders.^7,8 However, most of these approaches require processing temperatures in excess of 800°C, making them incompatible with the glass substrates and the conductive rear-contact layers required to create a photovoltaic device.⁶ Niu et al. have developed solid state approaches that can synthesize BaZrS₃ at temperatures of 600°C. ⁹ However, these synthesized BaZrS₃ powders are not easily translated into films usable for photovoltaic applications. Comparotto et al. recently synthesized crystalline BaZrS₃ films using sputtered Ba-Zr precursors followed by sulfurization at temperatures below 600°C, ⁶ but these films contained tin impurities and their use of vacuum-based processing may limit the possibility of high-throughput production of chalcogenide perovskites. Creating a solution-based deposition route for synthesizing chalcogenide perovskites may allow for cheaper, higher-throughput synthesis of chalcogenide-perovskite based materials, however, no direct solution-based deposition of chalcogenide perovskites has been reported to date. ¹⁰

Ingram et al. have demonstrated that metal dithiocarbamates can be used as precursors to synthesize hexagonal BaTiS₃ nanorods through a liquid phase reaction, yet, synthesis of BaZrS₃ and BaHfS₃ was not reported.¹¹ We have developed a novel route to synthesize BaZrS₃, BaHfS_3, and BaTiS₃ through solution-based deposition of organometallic precursors that can create crystalline chalcogenide perovskites at temperatures below 600°C. Barium dithiocarboxylic acids and zirconium, hafnium, or titanium dithiocarbamates are first synthesized by reacting organometallic and metal organic precursors with carbon disulfide through insertion reactions. The resulting products are combined in a coating solvent, cast onto glass substrates, and annealed in an inert atmosphere. A final sulfurization step is then required to create crystalline grains. A time and temperature study on the final sulfurization step has demonstrated that crystalline BaZrS₃, BaHfS_3, and BaTiS₃ can be synthesized in as little as 10 minutes at temperatures ranging from 500°C to 575°C. NMR and SCXRD were used to determine the identity of the metal dithiocarbamate and metal dithiocarboxylic acid precursors used in the synthesis of the perovskite materials. PXRD, Raman spectroscopy, and SEM-EDX were used to verify the proposed synthesis of the chalcogenide perovskite materials. The optoelectronic properties of these materials were investigated using photoluminescence spectroscopy and time-resolved photoluminescence to study their defect-related properties.

(1) Tiwari, D.; Hutter, O. S.; Longo, G. Chalcogenide Perovskites for Photovoltaics: Current Status and Prospects. Journal of Physics: Energy 2021, 3 (3), 034010. https://doi.org/10.1088/2515-7655/abf41c.

(2) Sharma, S.; Ward, Z.; Bhimani, K.; Li, K.; Lakhnot, A.; Jain, R.; Shi, S.-F.; Terrones, H.; Koratkar, N. Bandgap Tuning in BaZrS 3 Perovskite Thin Films. ACS Applied Electronic Materials 2021, 3 (8), 3306–3312. https://doi.org/10.1021/acsaelm.1c00575.

(3) Márquez, J. A.; Rusu, M.; Hempel, H.; Ahmet, I. Y.; Kölbach, M.; Simsek, I.; Choubrac, L.; Gurieva, G.; Gunder, R.; Schorr, S.; Unold, T. BaZrS3 Chalcogenide Perovskite Thin Films by H2S Sulfurization of Oxide Precursors. The Journal of Physical Chemistry Letters 2021, 12 (8), 2148–2153. https://doi.org/10.1021/acs.jpclett.1c00177.

(4) Sadeghi, I.; Ye, K.; Xu, M.; Li, Y.; LeBeau, J. M.; Jaramillo, R. Making BaZrS3 Chalcogenide Perovskite Thin Films by Molecular Beam Epitaxy. Advanced Functional Materials 2021, 31 (45), 2105563. https://doi.org/10.1002/adfm.202105563.

(5) Surendran, M.; Chen, H.; Zhao, B.; Thind, A. S.; Singh, S.; Orvis, T.; Zhao, H.; Han, J.-K.; Htoon, H.; Kawasaki, M.; Mishra, R.; Ravichandran, J. Epitaxial Thin Films of a Chalcogenide Perovskite. Chemistry of Materials 2021, 33 (18), 7457–7464. https://doi.org/10.1021/acs.chemmater.1c02202.

(6) Comparotto, C.; Ström, P.; Donzel-Gargand, O.; Kubart, T.; Scragg, J. J. S. Synthesis of BaZrS 3 Perovskite Thin Films at a Moderate Temperature on Conductive Substrates. ACS Applied Energy Materials 2022, 5 (5), 6335–6343. https://doi.org/10.1021/acsaem.2c00704.

(7) Niu, S.; Zhao, B.; Ye, K.; Bianco, E.; Zhou, J.; McConney, M. E.; Settens, C.; Haiges, R.; Jaramillo, R.; Ravichandran, J. Crystal Growth and Structural Analysis of Perovskite Chalcogenide BaZrS 3 and Ruddlesden–Popper Phase Ba 3 Zr 2 S 7. Journal of Materials Research 2019, 34 (22), 3819–3826. https://doi.org/10.1557/jmr.2019.348.

(8) Ravi, V. K.; Yu, S. H.; Rajput, P. K.; Nayak, C.; Bhattacharyya, D.; Chung, D. S.; Nag, A. Colloidal BaZrS 3 Chalcogenide Perovskite Nanocrystals for Thin Film Device Fabrication. Nanoscale 2021, 13 (3), 1616–1623. https://doi.org/10.1039/D0NR08078K.

(9) Niu, S.; Huyan, H.; Liu, Y.; Yeung, M.; Ye, K.; Blankemeier, L.; Orvis, T.; Sarkar, D.; Singh, D. J.; Kapadia, R.; Ravichandran, J. Bandgap Control via Structural and Chemical Tuning of Transition Metal Perovskite Chalcogenides. Advanced Materials 2017, 29 (9), 1604733. https://doi.org/10.1002/adma.201604733.

(10) Sopiha, K. v; Comparotto, C.; Márquez, J. A.; Scragg, J. J. S. Chalcogenide Perovskites: Tantalizing Prospects, Challenging Materials. Advanced Optical Materials. December 13, 2021, p 2101704. https://doi.org/10.1002/adom.202101704.

(11) Ingram, N. E.; Jordan, B. J.; Donnadieu, B.; Creutz, S. E. Barium and Titanium Dithiocarbamates as Precursors for Colloidal Nanocrystals of Emerging Optoelectronic Materials. Dalton Transactions 2021, 50 (44), 15978–15982. https://doi.org/10.1039/d1dt03018c.