Efficient green-emitting perovskite light-emitting diodes using a conjugated polyelectrolyte additive

Charge carrier confinement and defect passivation are the main research struggle for the development of efficient perovskite light-emitting diodes (PeLEDs). In this study, we report a green-emitting PeLED by adding an anionic conjugated polyelectrolyte containing tetraethylammonium counter ions (MPS2-TEA) into formamidinium lead tribromide quasi-2D perovskites. X-ray diffraction shows that perovskite films with MPS2-TEA are more randomly oriented compared to the films without MPS2-TEA. Interestingly, the incorporation of MPS2-TEA reduces the roughness of surfaces and grain sizes of the perovskite films. The increases in photoluminescence intensity (by three times) and lifetime (18.11 vs. 9.81 ns) of perovskite films with MPS2-TEA compared to those of the pristine films suggest improved radiative recombination by intermixing perovskite with MPS2-TEA. Defect density in perovskite films with MPS2-TEA is significantly suppressed owing to defect passivation at the grain boundaries by MPS2-TEA. The PeLED with MPS2-TEA shows a significantly improved external quantum efficiency of up to 15.47%, the current efficiency of 69.02 cd/A, and maximum luminance of 12,252 cd/m2, compared to a device without MPS2-TEA.