Application of Metallocenes in Lead-Free Tin Perovskite Optoelectronics

在短短十多年的研究中，钙钛矿太阳能电池（PSCs）已经成为一种令人兴奋的新型光伏技术。自2009年首次发表PSCs以来，功率转换效率（PCE）从3.8%提高到25.5%，使PSCs成为迄今为止发展最快的光伏技术。然而，目前需要铅（Pb）来实现高效率。因此，铅钙钛矿装置的广泛商业化规模引起了人们对铅可能造成的潜在健康和环境危害的主要关注。这使得开发无铅和环保的钙钛矿替代品成为当务之急。这个项目解决了这个重要的问题。锡（Sn）基钙钛矿已成为铅的一个有吸引力的替代品。然而，锡钙钛矿太阳能电池的性能和稳定性仍然落后于铅基太阳能电池。挑战是众所周知的：(i)不良的薄膜形态，需要建立新的加工方法来获得高结晶，无缺陷的薄膜；（ii） Sn2+快速氧化为Sn4+，导致自掺杂和Sn空位的形成，从而导致稳定性差[1]。本项目将重点研究使用茂金属基还原剂添加剂（在薄膜加工步骤和后处理中）来控制缺陷浓度、薄膜形态以提高器件性能（功率转换效率和稳定性）。一系列的实验表征技术将被使用，包括时间分辨光谱学来探测钙钛矿材料和异质结中的电荷转移动力学。这些研究将补充器件制造和光电子分析。在此，我们将阐明定量结构-功能关系，可用于指导开发与高性能兼容的新材料。这项研究的成果将适用于目前采用无铅锡基钙钛矿的一系列设备（例如led、光电二极管、传感器以及太阳能电池）。参考文献：[1]L. Lanzetta， T. Webb等，Nat. comm . 12, 2853,（2021）。

: 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).