Practical application of hybrid Pb-based halide perovskites needs not only to fabricate high-quality film samples on a large scale but also to properly overcome the issues of Pb toxicity and materials instability. Finding new, stable, Pb-free perovskites currently attracts significant research interest. Among various strategies, hetero-substitution of Pb to form quaternary halide double perovskites represents a promising direction to keep the high structural (and likely electronic) dimensionality nature of perovskite lattice and meanwhile offers rich chemical compositions a degree of freedom for discovering new perovskite materials. We herein present a perspective that concisely reviews the progress of rational design of Pb-free halide double perovskites by both theoretical and experimental efforts as well as their current and potential applications in various optoelectronic categories. We also envision the future research directions to realize new materials by exploring broader chemical composition space and to better utilize existing materials by considering optoelectronic properties modulation.

杂化的基于铅的卤化物钙钛矿的实际应用不仅需要大规模制造高质量的薄膜样品，还需要适当地克服铅的毒性和材料不稳定性的问题。寻找新的，稳定的，无铅的钙钛矿目前引起了巨大的研究兴趣。在各种策略中，Pb的异位取代形成季卤化物双钙钛矿代表了保持钙钛矿晶格的高结构（和可能的电子）维数性质的有前途的方向，同时为丰富的化学成分提供了发现新钙钛矿材料的自由度。我们在这里提出了一个观点，通过理论和实验努力以及它们在各种光电类别中的当前和潜在应用，简要回顾了无铅卤化物双钙钛矿的合理设计进展。我们还展望了未来的研究方向，以通过探索更广阔的化学组成空间来实现新材料，并通过考虑光电子性能调制来更好地利用现有材料。