Efficient and Stable Pure-Red Perovskite LED Based on Uniform Arrangement Strongly Confined Quantum-Dot Film

We reveal the nucleation and restriction growth of pure-red CsPbI 3 strongly confined quantum dots (SQDs). The iodine-rich precursor induced an iodine-rich surface on the CsPbI 3 crystals, preventing the absorption of [PbI 6 ] 4–, thus inhibiting the growth of crystals and improving the dimensional homogeneity of the SQDs. The Gaussian variance of the SQDs is only 0.01 nm, which is lower than 1 order of magnitude of the conventional QDs, demonstrating uniform crystal size distribution. Gaussian fitting and Chebyshev orientation parameter demonstrate a much higher degree of order in the SQD film than that in the conventional QD film. Thus, the uniform size and orderly arrangement of the SQDs endow their film with better electrical performance and stability. Light-emitting diode based on the SQDs manifested a pure-red electroluminescence peak at 635 nm, a brightness of 4609 cd/m 2, an external quantum efficiency of 25.4%, and a T 80 value of 268 min at 175 cd/m 2 .