Optical and Electronic Property Changes in Lead-free Perovskites by Metal Cation Transmutation
Bowon Yoo a, Alex Aziz b, Dibyajyoti Ghosh b, Hyejin Park a, M. Saiful Islam b, Saif A. Haque a
a Department of Chemistry and Centre for Plastic Electronics, Imperial College London, South Kensington Campus, London, United Kingdom
b Department of Chemistry, University of Bath, Bath BA2 7AY, UK
Proceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV19)
Roma, Italy, 2019 May 12th - 15th
Organizers: Prashant Kamat, Filippo De Angelis and Aldo Di Carlo
Oral, Bowon Yoo, presentation 044
DOI: https://doi.org/10.29363/nanoge.hopv.2019.044
Publication date: 11th February 2019

  Lead-based perovskites, APbX3, achieved over 23 % of efficiency within only 7 years after first their usage in solar cells. Although these lead-based perovskites have rapidly achieved the high efficiency, they have two intrinsic problems to be addressed to be commercialised; toxicity and instability. To address the problems of lead at the same time, new lead-free and air-stable perovskites such as bismuth- or antimony-based perovskites are emerging. However, the efficiency of the solar cells employing these new materials is relatively low below 5% with intrinsic problems; large binding energy, high defect, and large band gap.[1-4]

 Recently, it was reported that 10 times higher photo luminescence quantum yield (PLQY) was achieved by 7% of tin substitution on lead-based perovskite.[5] The reason for this improvement is not clear yet but we expect the similar effect can be brought when bismuth and antimony are mixed in a perovskite structure because the relationship between lead and tin is like that between bismuth and antimony. In a report, the improvement in defect density and varied defect states with the ratio of bismuth in the antimony perovskite, leading to doubled solar cell performance.[6]

 In this talk, we will present some of our results from the investigation on the bismuth and antimony mixed perovskites in (MA)3(BixSb1-x)2I9 structure. In particular, we will focus on the changes in structure and electronic and opto-electronic properties as changing the ratio of two atoms in the 0D perovskites by both experimental and theoretical methods.

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