High-performance multijunction perovskite LEDs with reduced interconnection loss

Tandem light-emitting diodes (LEDs) offer advantages in efficiency, brightness and lower the current density for a target brightness, but their implementation in solution-processed perovskite LEDs is limited by interconnection strategies that introduce high voltage penalties and poor robustness. Here we demonstrate a hierarchically structured interconnection layer (ICL) integrating a near-degenerate charge-generation junction with a crystalline-amorphous oxide composite, enabling low-barrier transport and solvent-tolerant stacking with reduced loss. Using this ICL, we realize double-junction perovskite LEDs in which two subunits operate efficiently in series, achieving a peak external quantum efficiency (EQE) of 42.6%, a maximum radiance of 690 W sr^-1 m^-2, and low driving voltage. The ICL is compatible with multiple perovskite emitters and supports scalable multijunction integration, yielding multijunction devices with sub-bandgap turn-on voltages and high EQEs exceeding 60%. Our results establish a low-loss interconnection strategy for series-stacked perovskite emitters, providing a practical route toward high-brightness and multi-wavelength perovskite light sources.