The possibility of lead (Pb) contamination and the volatility of the organic cations in the prevailing Pb-based organic-inorganic perovskite (HP) light absorbers are the two key issues of concern in the emerging perovskite solar cells (PSCs). The majority of the Pb-free HP candidates that are being explored for PSCs either suffer from instability issues and have unfavorable defect properties or have unsuitable bandgaps for PSC applications. We report the prediction of a promising new family of all-inorganic HPs based on the nontoxic, earth-abundant, ultrastable Ti(IV) for use in PSCs. We show that the Ti-based HPs possess a combination of several desirable attributes, including suitable bandgaps, excellent optical absorption, benign defect properties, and high stability. In particular, we show experimentally that representative members of the Ti-based HP family, Cs₂TiI_xBr_6–x, have bandgaps that can be tuned between the ideal values of 1.38 and 1.78 eV for single-junction and tandem photovoltaic applications, respectively.

中文翻译：

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基于地球的无毒钛（IV）空位订购的双钙钛矿卤化物，具有1.0至1.8 eV可调带隙，适用于光伏应用

流行的基于Pb的有机无机钙钛矿（HP）光吸收剂中铅（Pb）污染的可能性和有机阳离子的挥发性是新兴的钙钛矿太阳能电池（PSC）中关注的两个关键问题。正在探索用于PSC的大多数无铅HP候选产品都存在不稳定问题，具有不利的缺陷特性，或者具有不适用于PSC应用的带隙。我们报告了基于无毒，富含地球，超稳定的Ti（IV）用于PSC的全无机HP新家族的预测。我们表明，基于Ti的HP具有几种理想属性的组合，包括合适的带隙，出色的光吸收，良性缺陷性质和高稳定性。尤其是，₂ TiI _x Br _{6– x的}带隙可分别在单结和串联光伏应用的理想值1.38和1.78 eV之间调整。