Deep-Blue Perovskite Light-Emitting Diodes Realized by a Dynamic Interfacial Ion Exchange

Abstract

The external quantum efficiency (EQE) of the skyblue perovskite light-emitting diodes (PeLEDs) has reached 18.65%. However, the EQE of the deep-blue PeLEDs is still inferior to that of sky-blue PeLEDs, which restricts the PeLED application in displays. Herein, a novel dynamic interfacial ionexchange technique is developed to obtain deep-blue PeLEDs. By spin-coating quaternary ammonium chloride on top of a quasi-2D green perovskite film, a 68 nm spectral transition from green light emission at 513 nm to deep-blue light emission at 445 nm has been successfully realized. To the best of our knowledge, it is the largest spectrum transition ever achieved. By further introducing tricyclohexylphosphine oxide into the perovskite precursor solution to passivate defects, high-quality deep-blue PeLEDs have been fabricated with color coordinates at (0.13, 0.06). The maximum EQE reaches 1.8%, and the peak luminance reaches 847 cd/m 2 .

Donor–π–Acceptor Porphyrin-Assisted Bifunctional Defect Passivation for Enhanced Temporal Domain-/Wavelength-Dependent Nonlinear Absorption Properties in Perovskite Films

“…All perovskite samples showed main emission peaks located at 781 nm; however, enhanced PL intensities were observed for the Por1 -, Por2 -, and Por3 -passivated MAPbI 3 films as compared with the pristine MAPbI 3 film. PL intensity increment means porphyrin passivation can notably decrease the trap state density to mitigate nonradiative charge recombination loss in perovskite. − Time-resolved photoluminescence (TRPL) technique was employed to furnish more complementary evidence for the dynamic effect of porphyrin passivation on perovskite defect. PL decay curves were subjected to fitting using the double exponential decay function formulated as follows where y 0 is a constant for each transient background offset, A 1 and A 2 represent PL decay amplitudes, τ 1 represents a fast component accounting for the charge trapping nonradiative recombination, and τ 2 corresponds to a slow component associated with the process of detrapping and radiative recombination of photogenerated carriers. , As illustrated in Figure c, the pristine MAPbI 3 film exhibited a rapid PL decay process with lifetimes calculated as τ 1 = 0.58 ns and τ 2 = 38.04 ns, whereas much longer lifetimes were observed in MAPbI 3 films passivated by Por1 (τ 1 = 0.61 ns and τ 2 = 59.24 ns), Por2 (τ 1 = 0.62 ns and τ 2 = 79.36 ns), and Por3 (τ 1 = 0.60 ns and τ 2 = 99.97 ns).…”