Exciton engineering in two-dimensional (2D) hybrid metal halide perovskites (HMHPs) is crucial for optimizing photoluminescent (PL) and photocurrent (PC) properties, yet it remains a great challenge. In this work, high pressure is applied to accurately control the conversion equilibrium among free carriers (FCs), free excitons (FEs), and trapped excitons in 2D HMHPs of 10% Pb2+-doped BDACdBr4 (BDA = 1, 4-butanediamine). Initial compression induces noticeable interlayer approach and limited intralayer distortion. Reduced self-trapping energy facilitates reverse intersystem crossing of self-trapped excitons (STEs), leading to visible PL transformation from STE to FE emission. Under sufficient compression, phase transition occurs, and significant structural distortions are accompanied by further exciton release. The FE emission is enhanced with more symmetric line shape, achieving intense deep-blue emission that meets the international specification of deep-blue display. Sufficiently decreased binding energy also promotes the dissociation of FEs to simultaneously enhance PC property.

中文翻译：

---

二维金属卤化物钙钛矿中的高压激子工程，面向强烈的深蓝光发射和受调节的光电流特性


二维 （2D） 杂化金属卤化物钙钛矿 （HMHP） 中的激子工程对于优化光致发光 （PL） 和光电流 （PC） 特性至关重要，但它仍然是一个巨大的挑战。在这项工作中，施加高压以精确控制 10% Pb2+ 掺杂 BDACdBr4 （BDA = 1， 4-丁二胺） 的 2D HMHP 中自由载流子 （FC） 、自由激子 （FE） 和捕获激子之间的转换平衡。初始压缩导致明显的层间接近和有限的层内变形。降低的自捕获能量促进了自捕获激子 （STE） 的反向系统间交叉，导致从 STE 到 FE 发射的可见 PL 转变。在充分压缩下，发生相变，显著的结构变形伴随着进一步的激子释放。FE 发射通过更对称的线形得到增强，实现强烈的深蓝光发射，符合国际深蓝光显示规范。充分降低的结合能也促进了 FE 的解离，同时增强了 PC 性能。