  2D hybrid organic-inorganic semiconductors (HOIS) are low-cost,
self-assembled semiconductors that have proven to be vital for novel
optoelectronic devices due to their inherent stable excitons even at room
temperature. 2D HOIS are chemically stable with respect to the 3D analogues,
but their inherent anisotropy complicates their implementation in devices,
including electroluminescence (EL) devices. We report on the synthesis,
characterization, cathodoluminescence and EL of a new 2D HOIS, (4-fluoro
phenethylamine-H)2PbBr4, and its defect variations (DVs). The latter, in
contrast to the pristine material, allow for the first time the simple
fabrication of a prototype blue EL device by coating DVs on a conducting anode
substrate and using a Ga/In droplet cathode. DVs' optimization can lead to
improved light emitting devices (LEDs) and the work here is expected to provide
the incentive for utilizing HOIS DVs, as these are compatible with industrial
scale synthesis. In contrast to the pristine iodine analogue, whose thin films
readily provide EL, only the DVs or mixtures with MoS2 nano-sized platelets
provide EL, after careful deposition. These exhibit defects that disrupt the
planar non-conductive nature of the micrometric 2D HOIS platelets, usually
aligned parallel to the substrate, thus, providing mechanisms for current flow.
Finally, the choice of the fluorine-modified amine enhances the functionality
of the DVs as LED materials compared to using unmodified amine due to the
repulsion among the amine tails, leading to stable decorated 2D inorganic
sheets that are weakly bound.
