Framing emission gain layers for perovskite light-emitting diodes using polycaprolactone-silver nanoparticles featuring Förster resonance energy transfer and Purcell effects

In this study, a new emission gain layer for perovskite light-emitting diodes (PeLEDs) is presented to improve their performance. The emission gain layer consisting of absorption-stable silver nanoparticles is prepared using the post-addition method of the polycaprolactone capping agent (PCL@AgNPs-P). This layer (PCL@AgNPs-P) effectively improves the Förster resonance energy transfer (FRET) between the low-<i>n</i> (minor) and high-<i>n</i> (major) phases in a quasi2D perovskite system, thereby increasing the major emission intensity and efficiency. Moreover, this layer also enhances the Purcell effect, thus increasing the spontaneous emission rates and amplifying the electroluminescence. These combined advantages enable the derived PeLED to achieve higher luminance, external quantum efficiency (EQE), and sustained emission purity. As a result, the optimized PeLED with the PCL@AgNPs-P emission gain layer delivers a maximum luminance of 11 320 cd m^-2 and an EQE of 15.5%, and maintains high green wavelength emission purity and a narrow emission half-maximum width at various operating currents. Our results not only provide a robust pathway for the development of high-performance PeLEDs, but also open up the possibilities of applying PeLEDs in laser optics, where enhanced efficiency and emission characteristics are crucial for creating efficient and high-emission laser sources.