GaN and relate (Al, In, Ga)N alloys can produce blue- and green-light-emitting-diodes (LEDs) for full color displays and signals although they contain a high density of structural defects such as threading dislocations (TDs) and stacking faults. Both Quantum Wells (QW) and three-dimensional (3D) bulk films of InGaN exhibit high emission efficiency due to the recombination of excitons localized at certain potential minima originating from InN-rich lower bandgap regions. Hole function localization was predicted to be centered around In atoms in dilute cubic InGaN, using large-scale atomistic empirical pseudopotential calculations. Defect-insensitive nature of NBE emission probability in bulk films of In-containing InGaN, AlInN and AlInGaN was explained. The use of atomically inhomogeneous crystals alloyed or doped with exotic atoms for future innovations in efficient light emitters even when using defective crystals was proposed was proposed.