The Valleytronics term was first coined in 2012, meaning a technology similar to electronics - but using control over the valley degree of freedom in certain semiconductors.
In simple terms - electronics uses electrons (the carriers of electric charge) to retain and move data. Spintronics is similar but uses the spin of electrons. Valleytronics aims to control the valley freedom of electrons, and use that to save data (memory) or move it around (calculations).
There are several materials that were proposed as valleytronics materials - including silicon, diamond, carbon nanotubes, graphene, and silicene.