Dual P=O Groups Additive Synergistic Anti-Solvent Enables Efficient and Stable Quasi-2D Red Perovskite LEDs

Abstract

Quasi-two-dimensional (quasi-2D) mixed iodine/bromine halides perovskites are promising emitters for cost-effective, high-efficiency red perovskite light-emitting diodes (PeLEDs). But mixed-halide perovskites suffer from poor film quality and pronounced non-radiative losses, which hinder the improvement of device performance. To address these issues, we implement a synergistic anti-solvent-plus-additive protocol. High-volatility anti-solvents with different polarities and boiling points were introduced to rapidly remove residual solvents and improve film formation. Concurrently, a bifunctional conductive molecule, 2,7-bis(diphenylphosphoryl)-9,9’-spirobifluorene (SPPO13), containing two P=O functional groups was incorporated into the anti-solvent as an additive to passivate Pb²⁺ defects and facilitates balanced charge injection. This approach yielded red PeLED with an emission peak at 660 nm, a peak luminance (Lmax) of 3084 cd/m² and a maximum external quantum efficiency (EQEmax) of 5.63%, with International Commission on Illumination (CIE) coordinates of (0.715, 0.282). Furthermore, device stability was significantly improved, showing a lifetime (T50) of 39.65 h. These performance metrics are 2.71, 5.26, and 4.92 times that of the reference device (Lmax is 1140 cd/m², EQEmax is 1.07%, T50 is 8.06 h), respectively. The results in this study provide a viable pathway toward high-efficiency and stable quasi-2D red PeLEDs.