Publication date: 28th August 2024
Use of additives to achieve careful control over perovskite morphology and interfaces can provide high-performance LEDs in the infrared and visible. I will discuss some recent examples where high efficiencies and high brightness can be obtained. Why, though, are efficiencies generally so high? Where extraction barriers are large, electron and hole injection must be well-balanced, and I will show how this is achieved through redistribution of the field across the two transport layers. I will also show that light emission is rather uniform throughout the thickness of the devices despite the fact that electron and hole distributions are highly non-uniform. Finally I will discuss optical outcoupling efficiency, highlighting the role of photon recycling where waveguided photons are absorbed and remitted, giving additional chances to escape. I will demonstrate a simple technique to enhance photon recycling by reducing parasitic optical absorption in the device, giving a significant boost to the overall device efficiency.