Plasmonic nanoparticles boost low-current perovskite LEDs governed by photon recycling effects

Perovskite light-emitting diodes (PeLEDs) have emerged as a promising technology for next-generation display and lighting applications, thanks to their remarkable colour purity, tunability, and ease of fabrication. In this work, we explore the incorporation of plasmonic spherical nanoparticles (NPs) directly embedded into the green-emitting CsPbBr₃ perovskite layer in a PeLED as a strategy to enhance both its optical and electrical properties. We find that plasmonic effects directly boost spontaneous emission while also influencing charge carrier recombination dynamics. We present a rigorous theoretical electro-optical analysis to systematically investigate the impact of NP metal, size, and concentration on device performance, with particular emphasis on the role of photon recycling (PR). Our results demonstrate that embedding carefully designed silver (Ag) NPs, selected through rigorous theoretical modelling, into PeLEDs leads to enhanced device performance across a wide range of operating currents. Notably, we observe a 4-fold improvement in external quantum efficiency (EQE) at injection currents as low as 0.02 mA cm^-2, and a 2-fold enhancement at 0.2 mA cm^-2, attributed to increased radiative recombination. Furthermore, results suggest improved efficiency retention at higher injection levels, pointing to reduced current roll-off limitations and extended high-brightness operation. Additionally, PR plays a crucial role in mitigating optical losses and improving outcoupling efficiency, especially in plasmonic-enhanced systems, where scattering effects increase the prevalence of trapping states. These findings open up exciting possibilities for devices requiring energy-efficient, compact, and high-performance light sources, such as portable electronics and low-power displays.