Organic semiconductor materials for fabricating organic light emitting diodes (OLEDs) have attracted significant attention in the field of novel optical and optoelectronic devices. Particulation of OLEDs’ emitting materials in small-scale has been limited only to tris(8-hydroxyquinoline) aluminum (Alq3) that emits green-light. In this study, we attempted to fabricate, for the first time, red-light emitting nanoparticles of phosphorescent organic semiconductor of bis(1-phenylisoquinoline) (acetylacetonate) iridium (Ir(piq)2(acac)). Rectangular particles with length and thickness of ∼2 μm and ∼50 nm were fabricated with guidance of cetyltrimethylammonium bromide (CTAB) and micro-plates with length and thickness of ∼5 μm and ∼100 nm were fabricated by sodium dodecyl sulfate (SDS). By contrast, single-stranded DNA (ssDNA) induced nano-rods with dimension of ∼400 nm in length and 100 nm in thickness. Hence, the choice of guiding agents resulted in distinctive crystal characteristic so that the nanorods by ssDNAs showed UV absorption with a red-shift in metal-ligand charge transfer (MLCT) by 54 nm whereas the particles by surfactants did 35 nm compared to the dissolved precursor. Higher was the ssDNA-guided nanorods in relative phosphorescence of the intensity at 610 nm over that at 695 nm than the surfactant-guided particles.