Smoothing Energy Transfer Enabling Efficient Large-Area Quasi-2D Perovskite Light-Emitting Diodes

Electroluminescence (EL) efficiency of perovskite light-emitting diodes (PeLEDs) based on a few square millimeters has improved significantly in recent years. Nevertheless, the EL efficiency of PeLEDs would plunge once the active area is enlarged from a millimeter to even a subcentimeter due to the unsmooth energy transfer process among the edge region with numerous nonradiative recombination centers. Herein, an intriguing strategy is developed to realize high-quality quasi-2D perovskite thin film via tuning perovskite precursor rheological properties as well as modulating the substrate surface tension. The perovskite crystallization process is retarded by incorporating a strong chelating ligand into its precursor. Hydroxylamine-O-sulfonic acid, containing a sulfonic acid group and an amino group, acts as a strong chelating agent with lead ions (Pb2+), which exhibit great synergistic potential in defect passivation and crystallization modulation. As a result, a large-area (25 cm(2)) quasi-2D PeLED achieves an external quantum efficiency of 20.7% with uniform emitting characteristics, a record value among analogous same-size PeLEDs. The work may pave the way to realize high-performance large-area perovskite optoelectronic devices.