Suppressing phase disproportionation in quasi-2D perovskite light- emitting diodes

K Wang and ZY Lin and ZH Zhang and LR Jin and K Ma and AH Coffey and HR Atapattu and Y Gao and JY Park and ZT Wei and BP Finkenauer and CH Zhu and XE Meng and SN Chowdhury and ZY Chen and T Terlier and TH Do and Y Yao and KR Graham and A Boltasseva and TF Guo and LB Huang and HW Gao and BM Savoie and LT Dou, NATURE COMMUNICATIONS, 14, 397 (2023).

DOI: 10.1038/s41467-023-36118-7

Electroluminescence efficiencies and stabilities of quasi-two- dimensional halide perovskites are restricted by the formation of multiple-quantum-well structures with broad and uncontrollable phase distributions. Here, we report a ligand design strategy to substantially suppress diffusion-limited phase disproportionation, thereby enabling better phase control. We demonstrate that extending the pi-conjugation length and increasing the cross-sectional area of the ligand enables perovskite thin films with dramatically suppressed ion transport, narrowed phase distributions, reduced defect densities, and enhanced radiative recombination efficiencies. Consequently, we achieved efficient and stable deep-red light-emitting diodes with a peak external quantum efficiency of 26.3% (average 22.9% among 70 devices and cross- checked) and a half-life of similar to 220 and 2.8 h under a constant current density of 0.1 and 12 mA/cm(2), respectively. Our devices also exhibit wide wavelength tunability and improved spectral and phase stability compared with existing perovskite light-emitting diodes. These discoveries provide critical insights into the molecular design and crystallization kinetics of low-dimensional perovskite semiconductors for light-emitting devices.

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