Halide perovskites have swiftly been elevated to a subject worthy of serious and extensive research. They are unequivocally an unprecedented class of semiconductors with a broad range of optoelectronic applications. These materials display outstanding properties, which are the results of their direct and tunable band-gap, high electron/hole mobility, strong light-absorption coefficient, and high defect tolerance coupled with low non-radiative recombination rates. Their preparation is also extremely easy and compatible with room-temperature deposition processes. Nonetheless, the toxic nature of lead (Pb and its ions) and the poor stability against moisture, limit their mass production and commercialization. This article thoroughly reviews the recent investigations undertaken to solve these thorny problems by focusing mainly on the structural development and the photoluminescence tuning ability of lead-free perovskite nanocrystals (NCs). In the light of the principles related to crystal chemistry, we present the development of perovskite NCs from mineral prototypes, which leads to a variety of multi component Pb²⁺-free perovskite type compounds. Then, assuming that the ultimate goal is the production of a single-component white-light emission device, we shed light on the development of broadly tunable Pb²⁺-free perovskite NCs with intrinsic emission as well as extrinsic emission achieved by doping with various ions, and on the corresponding energy transfer (ET) mechanism, which governs the color and the photoluminescence emission tuning ability. The present review aims to assist the research which deals with the discovery of new highly stable, nontoxic perovskite NCs, following a strategy associated with excitonic luminescence enhancement, in conjunction with a comprehensive understanding of the role of energy transfer phenomenon, whereby efficient tuning ability is achieved by various dopants.

卤化物钙钛矿已迅速提升为值得认真和广泛研究的课题。毫无疑问，它们是具有广泛光电应用的前所未有的半导体类别。这些材料具有出色的性能，这是其直接可调的带隙，高电子/空穴迁移率，强光吸收系数和高缺陷耐受性以及低非辐射重组率的结果。它们的制备也非常容易，并且与室温沉积工艺兼容。但是，铅（Pb及其离子）的毒性和对水分的稳定性差，限制了其的批量生产和商业化。本文通过主要关注无铅钙钛矿纳米晶体（NCs）的结构发展和光致发光调谐能力，彻底回顾了为解决这些棘手问题而进行的最新研究。根据与晶体化学相关的原理，我们介绍了矿物原型中钙钛矿型NC的发展，这导致了多种多组分Pb^2+无钙钛矿型化合物。然后，假设最终目标是生产单组分白光发射器件，我们将着重研究可调谐的，无Pb ^2+的钙钛矿型NC的发展，该NC具有固有发射以及通过掺杂各种杂质而实现的非固有发射离子，并具有相应的能量转移（ET）机理，该机理决定着颜色和光致发光发射调谐能力。本综述旨在协助研究新的高度稳定，无毒的钙钛矿型NC，并遵循与激子发光增强相关的策略，并全面了解能量转移现象的作用，从而有效地调节能力通过各种掺杂剂实现。