  The new class of hybrid organic-inorganic semiconductor (HOIS) materials,
based on halide perovskites, is constantly being pursued for applications such
as Light Emitting Diodes (LEDs) and solar cells, due to their momentous
optoelectronic properties. In this work, we present a single layer LED that
operates due to energy transfer effects as well as a simple, instant and low
cost method for its fabrication. A LED device based on a mixture of zero
dimensional (OD) (CH 3 NH 3 ) 4 PbI 6, two dimensional (2D) (F- C 6 H 4 CH 2 CH
2 NH 2 ) 2 PbI 4 and three dimensional (3D) (CH 3 NH 3 )PbI 3 HOIS, is
presented for the first time. The final composite material manifests simple,
yet unique energy transfer optical effects, while its electroluminescence
exhibits excitonic recombination bright yellow light, peaked at 592 nm. LED
device fabricated under ambient air, readily functions at room temperature and
low voltages. As for the active layer, it exhibited substantial film continuity
in any form of deposition. Finally, with appropriate mixtures, it is possible
to create films containing phase changes that exhibit dual color emission, here
presented as yellow-green.
