Low-cost and high-efficiency perovskite light-emitting diodes with all-solution-processed functional layers

Metal halide perovskite light-emitting diodes (LEDs) possess high external quantum efficiency (EQE) and color purity, indicating great promise for next-generation panel displays. In state-of-the-art perovskite LEDs, the hole transport layers and perovskite thin films are solution-processed, whereas the electron transport layers are fabricated through vacuum evaporation deposition. The latter method raises concerns about material waste and environmental pollution, as well as prolonged production duration and increased costs, thereby posing challenges for scalable and sustainable manufacturing. Here, we demonstrate a systematic solvent screening strategy for fabricating perovskite LEDs based on all-solution-processed functional layers. We use ethyl acetate to spin-coat the electron transport material onto perovskite thin films, thereby preserving the device's structural integrity. The as-fabricated deep-red perovskite LEDs show a peak EQE of 4.04% and a maximum radiance of 8,221 mW sr⁻¹ m⁻², among the best performances of all-solution-processed perovskite LEDs. Quantitative analysis indicates that, compared to vacuum evaporation deposition, the material costs, processing duration, and equipment expenses have been reduced by 82%, 90%, and 95%, respectively. Our work establishes a promising construction strategy for solution-processed optoelectronic devices with low cost and high performance, thereby bringing them a significant step closer to their further industrialization and commercialization.