Colloidal Synthesis of Alkali Metal-based Chalcogenide Na-Cu-S Nanocrystals for Energy Conversion

The global energy crisis has promoted a faster transition to cleaner energy within research fields in the form of energy conversion devices (ECDs). Many semiconductors have been produced in recent years with outstanding properties. Albeit there has yet to be a material which can achieve great properties while fulfilling green principles of high abundance and biocompatibility.

The search for novel materials has recently brought research attention to perovskite inspired materials (PIMs). This idea suggests mimicking perovskite structure using stable, nontoxic alternative elements can bridge the gap to commercial realisation.^1,2 Alkali metal-based chalcogenides are one of the potential candidates for fulfilling the gaps left in the market by the failure of perovskites. Sodium is the 6^th most abundant element in the earth’s crust while copper and sulfur are plentiful and do not pose harmful effects like their predecessors. 

 Sodium copper sulfide nanocrystals have been theoretically screened for energy conversion applications showing optimal band gap and carrier mobilities.³ Here we report the realisation of this theoretical material into actuality. Through the use of the colloidal hot injection synthesis method, we have succeeded in producing NaCuS nanobelts. A solution phase synthesis for this material has yet to be reported in literature. The chemistry and reaction kinetics behind this material and its synthesis is the basis for this work.

References

(1)        Kumar, M.; Huang, Y.-T.; Kavanagh, S. R.; Scanlon, D. O.; Walsh, A.; Hoye, R. L. Z. Perovskite-Inspired Materials for Photovoltaics and beyond-from Design to Devices. Nanotechnology 2021, 32, 60. https://doi.org/10.1088/1361-6528/abcf6d.

(2)        Hoye, R. L. Z.; Schulz, P.; Schelhas, L. T.; Holder, A. M.; Stone, K. H.; Perkins, J. D.; Vigil-Fowler, D.; Siol, S.; Scanlon, D. O.; Zakutayev, A.; Walsh, A.; Smith, I. C.; Melot, B. C.; Kurchin, R. C.; Wang, Y.; Shi, J.; Marques, F. C.; Berry, J. J.; Tumas, W.; Lany, S.; Stevanović, V.; Toney, M. F.; Buonassisi, T. Perovskite-Inspired Photovoltaic Materials: Toward Best Practices in Materials Characterization and Calculations. Chemistry of Materials 2017, 29 (5), 1964–1988. https://doi.org/10.1021/acs.chemmater.6b03852.

(3)        Li, H.; Jiang, X.; Xu, X.; Xu, G.; Li, D.; Li, C.; Cui, B.; Liu, D.-S. High Mobility and Enhanced Photoelectric Performance of Two-Dimensional Ternary Compounds NaCuX (X = S, Se, and Te) †. Phys. Chem. Chem. Phys 2021, 23, 2475. https://doi.org/10.1039/d0cp05303a.