Scientists at Los Alamos National Laboratory are creating innovative 2D layered hybrid perovskites that allow greater freedom in designing and fabricating efficient optoelectronic devices. Applications could include low-cost solar cells, LEDs, laser diodes, detectors, and more. Their work could overturn conventional wisdom on the limitations of device designs based on layered perovskites. The new 2D, near-single-crystalline thin films have an out-of-plane orientation so that uninhibited charge transport occurs through the perovskite layers in planar devices. This research finds the existence of "layer-edge-states" at the edges of the perovskite layers which are key to both high efficiency of solar cells and high fluorescence efficiency for LEDs.