High-Performance Blue Perovskite Light-Emitting Diodes Based on the “Far-Field Plasmonic Effect” of Gold Nanoparticles

Metal halide perovskites have become the next-generation electroluminescent materials due to their excellent optoelectronic properties. In the last several years, there has been tremendous progress in the performance of red and green-light perovskite electroluminescent devices (PeLEDs) with external quantum efficiencies (EQE) exceeding 14% and 21% for red and green PeLEDs, respectively. In contrast, blue PeLEDs are still in infancy stage, due to EQEs below 1%. Therefore, development of blue PeLEDs is sorely needed since blue light plays a vital role in achieving full-color and white-light emission. In order to improve the efficiency of blue PeLEDs, herein we introduce gold nanoparticles (Au NPs) into the poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) hole transport layer (HTL) to achieve a high performannce blue PeLEDs with emission wavelength ~475 nm. By introducing Au NPs the optical properties of poly(ethylene oxide) (PEO): PEA2(CsPbBrxCl3−x)n−1PbBr4 perovskite films are significantly improved leading to 3.8 times enhancement in fluorescence intensity. Based on this improvement, the blue PeLEDs gain maximum luminance and EQE ~1110 cd/m2 and 1.64%, respectively. The performance of modified blue PeLED is among the best reported so far. Finally, such improvement in the performance is attributed to the far-field surface plasmonic effect of Au NPs. This effect is originated from the interference between original chromophores emission and mirror-reflected emission on the mirror-type substrates. Our study not only reveals the technological role of Au NPs in development of blue PeLEDs, but also offers new insights into the fundamental physics underlying the effect of surface plasmon resonance of Au NPs on perovskite light-emitting.