Prior work involving the detection and emission of light from semiconductor nanostructures has involved single crystalline nanomaterials. Here we review the use of electrodeposited, polycrystalline (pc), cadmium selenide (CdSe) in nanowires and nanogap device structures for photonics. The photodetectors and photon emitters we describe are symmetrical metal–semiconductor–metal (M-S-M) devices prepared either by the evaporation of two gold contacts onto linear arrays of pc-CdSe nanowires prepared using lithographically patterned nanowires electrodeposition (LPNE), or by the electrodeposition of pc-CdSe directly onto gold nanogaps. The properties of these devices for detecting light using photoconductivity, and for generating light by electroluminescence, are described.