Optoelectronics is the study and application of electronic devices that source, detect and control light. It's usually considered a sub-field of photonics.
In this context, besides visible light, invisible forms of radiation are included, such as gamma rays, X-rays, ultraviolet and infrared. Optoelectronic devices are electrical-to-optical or optical-to-electrical transducers or instruments that use such devices in their operation.
Electro-optics is often erroneously used as a synonym but is in fact a wider branch of physics that deals with all interactions between light and electric fields, whether or not they form part of an electronic device."
Materials used in optoelectronics are similar to those of semi-conductor materials, such as Si, Ge, Sn, SiC, Te, BN, AlN, GaN, CdTe, etc.
Source: Wikipedia; Optoelectronics, April 4th, 2014 (http://en.wikipedia.org/wiki/Optoelectronics)