The ideal optoelectronic semiconductor material would be a strong light emitter and an efficient charge conductor to allow for electrical injection in devices. These two conditions, when met, can lead to highly efficient LEDs as well as to solar cells that approach the Shockley-Queisser limit. Until now, the materials that have come closest to meeting these conditions have been based on costly, epitaxially-grown III-V semiconductors that cannot be monolithically integrated to CMOS electronics.