Extended Data Fig. 4: Characterizations of perovskite films and LEDs with various 5AVA amounts.

The ratio of 5AVA to FAI to PbI₂ is x/2.4/1, where x varies from 0 to 0.9. a, SEM images. The scale bars represent 1 μm. The value of x is given in the top left corner of each image. The reference FAPbI₃ perovskite film without 5AVA has low film coverage. Without 5AVA, the perovskites form discrete clusters with random shapes. After adding 5AVA, faceted perovskites with submicrometre structures gradually form. b, XRD spectra. The perovskite films show improved crystallinity with the addition of 5AVA. c, Excitation-intensity-dependent PLQE. After adding 5AVA, PLQEs were greatly enhanced, indicating reduced trap densities. d, Time-resolved PL decay transients (carrier density 1.0 × 10¹³ cm⁻³). There is a fast PL decay channel for the perovskite without 5AVA, indicating a high level of trap densities. This fast PL decay channel gradually disappears after adding 5AVA. e, Dependence of current density and radiance on the driving voltage. After adding 5AVA, the leakage current is reduced. f, EQE plotted against current density. g, Peak EQE plotted against 5AVA ratio. Error bars correspond to the standard deviation. After adding 5AVA, the peak EQE increases owing to reduced leakage current and enhanced PLQE. When the 5AVA ratio is increased to 0.9, the EQE decreases, owing to the inferior outcoupling efficiency that results from the more dispersed structural pattern.