An exemplary printable composition of a liquid or gel suspension of diodes comprises a plurality of diodes, a first solvent and/or a viscosity modifier. An exemplary diode comprises: a light emitting or absorbing region having a diameter between about 20 and 30 microns and a height between 2.5 to 7 microns; a plurality of first terminals spaced apart and coupled to the light emitting region peripherally on a first side, each first terminal of the plurality of first terminals having a height between about 0.5 to 2 microns; and one second terminal coupled centrally to a mesa region of the light emitting region on the first side, the second terminal having a height between 1 to 8 microns.