Bridging the Green Gap: Monochromatic InP-Based Quantum-Dot-on-Chip LEDs with over 50% Color Conversion Efficiency
Bega Karadza, Pieter Schiettecatte, Hannes Van Avermaet, Leila Mingabudinova, Luca Giordano, Dobromił Respekta, Yu‐Hao Deng, Igor Nakonechnyi, Kim De Nolf, Willem Walravens, Youri Meuret, Zeger Hens
Abstract
Solid-state light-emitting diodes (LEDs) emit nearly monochromatic light, yet seamless tuning of emission color throughout the visible region remains elusive. Color-converting powder phosphors are therefore used for making LEDs with a bespoke emission spectrum, yet broad emission lines and low absorption coefficients compromise the formation of small-footprint monochromatic LEDs. Color conversion by quantum dots (QDs) can address these issues, but high-performance monochromatic LEDs made using QDs free of restricted, hazardous elements remain to be demonstrated. Here, we show green, amber, and red LEDs formed using InP-based QDs as on-chip color convertor for blue LEDs. Implementing QDs with near-unity photoluminescence efficiency yields a color conversion efficiency over 50% with little intensity roll-off and nearly complete blue light rejection. Moreover, as the conversion efficiency is mostly limited by package losses, we conclude that on-chip color conversion using InP-based QDs can provide spectrum-on-demand LEDs, including monochromatic LEDs that bridge the green gap.