Application of Metallocenes in Lead-Free Tin Perovskite Optoelectronics

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: In just over a decade of research, perovskite solar cells (PSCs) have emerged as an exciting new PV technology. Since the first publication on PSCs in 2009, the power conversion efficiencies (PCE) have gone from 3.8 to 25.5 %, making PSCs the fastest growing PV technology to date. However, lead (Pb) is currently required to achieve high efficiencies. As such, the widespread commercial scaleup of Pb perovskite devices raises major concerns in relation to potential health and environmental hazards that Pb may cause. This makes the development of Pb-free and environmentally friendly perovskite alternatives a high priority. This project addresses this important issue. Tin (Sn) based perovskites have emerged as an attractive alternative to Pb. However, the performance and stability of Sn perovskite solar cells still lags behind that Pb-based systems. The challenges are well known: (i) poor film morphology and the need to establish new processing methods to achieve highly crystalline, defect-free films and (ii) the rapid oxidation of Sn2+ to Sn4+, resulting in self-doping and the formation of Sn vacancies and thus poor stability [1]. This project will focus on the use of metallocene-based reductant additives (in the film processing step and post-treatments) to control both the defect concentration, film morphology to improve device performance (power conversion efficiency and stability). A range of experimental characterization techniques will be used including time resolved optical spectroscopy to probe charge transfer dynamics in perovskite materials and heterojunctions. These studies will be complimented by device fabrication and optoelectronic analysis. Herein, we will elucidate quantitative structure-function relationships that can be used to guide the development of new materials compatible with high performance. The outputs of this research will be applicable to a range of devices (e.g. LEDs, photodiodes, sensors as well as solar cells) now employing lead-free, Sn-based perovskite.References:[1] L. Lanzetta, T. Webb et al., Nat. Commun. 12, 2853, (2021).