Broadband enhancement of quantum dot emission for microLED using Ag plasmonic nanoparticles

MicroLED display is emerging as a candidate to drive a new generation of display technology. Full-color microLED based on carbon-dots (CDs) and blue microLED utilizes photoluminescence (PL) of blue-excited red and green emission CDs to achieve large coverage of color gamut and low power consumption. There is a high demand to develop costeffective technologies to enhance CD emission and minimize blue excitation light leakage through the CD layer. Here we demonstrate the use of plasmonic nanoparticles to enhance multicolor CDs in the emitting layer of microLED while suppressing the transmission of blue excitation. Silver nanoparticles are known to have surface plasmon resonances in or close to the blue range. Blue excitation over an emitting layer formed by the mixture of CDs and metal nanoparticles leads to excitation enhancement of CDs and thus the increased quantum efficiency. We studied the emitting layers fabricated by dispersing a mixture of 30 nm silver nanoparticles and CDs at various ratios and obtained a maximum enhancement factor of ~8. The metal nanoparticles also absorbed the blue excitation and reduced the leakage of blue light. Fluorescence lifetime measurements showed negligible changes in the CD emission rate with and without the presence of metal nanoparticles. The analysis implies that the enhanced CD PL is a result of excitation enhancement rather than Purcell effect. This technique offers a low-cost, effective approach to improve the performance of microLED displays.