Organic-inorganic hybrid perovskite materials have attracted significant attention from academia and industry because of their unique structural and optoelectronic properties. The ability to achieve a perovskite layer with a uniform morphology, high crystallinity and charge-selective behaviour through interfacial engineering is critical for the preparation of high-efficiency perovskite optoelectronic devices. Here, we enhance the efficiencies of conventional structured perovskite optoelectronics by applying an amine-based solvent treatment and optimising the morphology of the perovskite layers. Such a polar solvent treatment enhances electron injection and extraction and reduces the recombination of photo-generated charges at the interface. In addition, a uniform and dense perovskite layer with full surface coverage was realised using adequate solvent, and nearly full coverage of green EL through the highly uniform morphology of the perovskite layer was observed in perovskite LEDs.