Protected valley states and generation of valley- and spin-polarized current in monolayer <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mrow><mml:mi>M</mml:mi><mml:mi>A</mml:mi></mml:mrow><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi>Z</mml:mi><mml:mn>4</mml:mn></mml:msub></mml:mrow></mml:math>

The optical selection rules obeyed by two-dimensional materials with spin-valley coupling enable the selective excitation of carriers. We show that six members monolayer MA2Z4 (M = Mo and W; A C, Si, Ge; Z N, P, As) family are direct band-gap semiconductors protected valley states circularly polarized infrared light can induce valley-selective inter-band transitions. Our optovalleytronic device demonstrates a close to 100% valley- spin-polarized current under in-plane bias light, which be exploited encode, process, store information.