Colloidal cesium lead bromide-based anisotropic nanorods for improving outcoupling in perovskite light-emitting diodes

Photon extraction is one of the major issues limiting outcoupling efficiency in perovskite light-emitting diodes (PeLEDs). Light outcoupling in PeLEDs is typically limited by the disparity in refractive indices among the consisting layers and the difficulty of producing directed emitters in the emitting layers. Here, anisotropic nanorod-based perovskite with colloidal cesium lead bromide was introduced to address the issue via the oil-water interface chemical stripping transition method. It was confirmed that the horizontal transition dipole moments of 73% and refractive index value of 1.86 of the ANRs-based perovskites enhance outcoupling efficiency in PeLEDs. Finally, we achieved green-emitting ANR-PeLEDs with a current efficiency of 45.9 cd/A, power efficiency of 40.0 lm/W, and external quantum efficiency of 18.4% (turn-on voltage 3.3 V), with Commission Internationale de l'Eclairage (CIE) coordinates of (0.073, 0.71). These findings suggest further research into the anisotropic 1D shape of perovskite, which could improve the optoelectrical performance of PeLEDs.