Comprehensive Crystal Regulation Reduces Interfacial Energy Loss for Efficient Blue Perovskite Light‐Emitting Diodes

As an essential component of future full-color displays, blue perovskite light-emitting diodes (PeLEDs) still lag far behind the red and green counterparts in the device performances. In the mainstream quasi-2D blue perovskite system, trap-mediated nonradiative loss, low energy transfer efficiency, and interface fluorescence quenching remain significant challenges. Herein, guanidinium thiocyanate (GASCN) and potassium cinnamate (PCA) are respectively introduced into the hole transport layer (HTL) and the perovskite precursor to achieve a dense and uniform perovskite thin film with greatly improved optoelectronic properties. Therefore, adequate GA