Highly Bright Silicon Nanocrystal White Light‐Emitting Diodes With Luminance in Excess of 10000 cd m⁻2

Abstract

Silicon (Si) light source has profound significance in monolithic integrated Si photonics. However, its luminance remains too low to meet practical use that usually requires > 10000 cd m⁻2. Here, an all‐inorganic Si nanocrystal (SiNC) white light‐emitting diode (WLED) with a continuous emission spectrum spanning ≈400–900 nm in wavelength, is reported. The architecture of the WLED comprises front electrode of Ag grids and transparent‐conducting‐oxide/electron transport layer (ETL) of ZnO/front charge confinement layer (CCL) of SiO2/active layer of low‐resistivity SiNC composite thin film/rear CCL of SiO2/hole transport layer (HTL) of MoO3/textured p‐Si substrate/rear electrode of aluminum/heat radiator. The main procedures for achieving high luminance here include combined applications of high‐pressure ammonia passivation of the active layer, which enhances its photoluminescence quantum yield significantly, and texturing of p‐Si substrate, which boosts the light extraction and charge injection effectively. With an optimized combination of passivation and texturing, luminance of 10751 cd m⁻2 is achieved with external quantum efficiency (EQE) of 0.26%. After a Peltier cooler is further applied, luminance of 12363 cd m⁻2 is attained with EQE of 0.30%. Following further technical iterations, this highly bright SiNC WLED shall find applications in monolithic integrated Si photonics and even Si general lighting.