Direct Band Gap Mixed-Valence Organic–inorganic Gold Perovskite as Visible Light Absorbers

Biplab Ghosh^a, Benny Febriansyah^a, Padinhare Harikesh^a, Teck Koh^a, Shreyash Hadke^a^,^b, Lydia Wong^a^,^c, Jason England^d, Subodh Mhaisalkar^a^,^c, Nripan Mathews^a^,^c

^aEnergy Research Institute / Nanyang Technological University, Singapore, Singapore

^bNTU Singapore - Nanyang Technological University, Interdisciplinary Graduate School, Nanyang Avenue, 50, Singapore, Singapore

^cNTU Singapore - Nanyang Technological University, School of Materials Science and Engineering, Nanyang Avenue, 50, Singapore, Singapore

^dNTU Singapore - Nanyang Technological University, Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Link, 21, Singapore, Singapore

Materials for Sustainable Development Conference (MATSUS)
Proceedings of Online nanoGe Fall Meeting 20 (OnlineNFM20)

#PerEmer20. Perovskite III: Emerging Metal Halide Semiconductors

Online, Spain, 2020 October 20th - 23rd

Organizers: Dmitry Dirin, Jacky Even and Constantinos Stoumpos

Contributed talk, Biplab Ghosh, presentation 150
Publication date: 4th October 2020

Lead-free perovskites are receiving ever increasing attention after inspiring success of lead-based halide perovskites, mostly due to atmospheric instability and lead toxicity associated with the latter. Despite significant progress in homovalent and heterovalent substitution of Pb with non-toxic elements, stable lead-free perovskites with an ideal bandgap (1.2-1.4 eV) for photovoltaics are still missing. In this work, we report organic-inorganic gold halide double perovskites ((CH3NH3)2Au2X6, X = Br, I) which shows ideal bandgap for photovolltaics. In contrast to other double perovskites, two different oxidation states (+1 and +3 for perovskite structure) of Au is stacked alternatively to form a halogen-bridged perovskite structure. These compounds are solution processable and show bandgap tunability by halide exchange. Density functional theory calculations confirm the direct nature of bandgaps of the compounds with small effective mass for excellent charge transport. In addition, the Au-halide perovskites show high chemical stability, low trap density, and reasonable photoresponse. These combined properties demonstrate that Au-based halide perovskites can be a promising group of compounds for optoelectronic applications.

References:

[1] Direct Band Gap Mixed-Valence Organic–inorganic Gold Perovskite as Visible Light Absorbers. Chem. Mater. 2020, 32, 15, 6318–6325

Acknowledgements:

This research was supported by the National Research Foundation, Prime Minister’s Office, Singapore under its Competitive Research Programme (CRP Award No. NRFCRP14-2014-03) and Intra-CREATE Collaborative Grant (NRF2018-ITC001-001). We would also like to thank Dr. Li Yongxin for helping us solve the crystal structures of the materials presented herein

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