Bright Single-Layer Perovskite Host–Ionic Guest Light-Emitting Electrochemical Cells

Perovskite light-emitting devices have drawn considerable attention for their favorable optoelectronic properties. High carrier mobilities make perovskites excellent candidates as host materials in electroluminescent devices, but perovskites have yet to be brought to their full potential in this role. To achieve high performance in a simple single-layer device, we employed a CsPbBr3 perovskite host and a novel ionic iridium complex guest along with a polyelectrolyte to demonstrate efficient light-emitting electrochemical cells (PeLECs). For an optimal guest/host blend, 10600 cd/m2 luminance at 11.6 cd/A and 9.04 Lm/W is achieved at 4.1 V, demonstrating greater than a 2-fold overall improvement of previous efforts and over a 2-fold efficiency enhancement over host-only devices. These devices showed a range of electroluminescence color proceeding from orange-red to green, facilitated by the reconfigurable ionic materials blend. Optimized devices exhibited stable operation under constant current driving, maintaining >630 cd/m2 emission for 40 h. Our rationally designed ionic guest at an optimal concentration of the host produced efficient (>90%) Förster energy transfer and improved thin film morphologies for high-performance PeLEC operation enabled by ionic migration to interfaces.