Soft X-ray photoemission study of thermoelectric alloys Fe2 − x − yIryV1 + xAl and Fe2 − xV1 + x − yTiyAl

► Valence-band structure of Fe2 − x − yIryV1 + xAl and Fe2 − xV1 + x − yTiyAl. ► Mid-pseudogap states derived from anti-site V and Fe defects. ► Band shift induced by partial substitution of Ir for Fe and V for Ti. ► Electronic structure change can explain enhancement of their thermoelectric power. ► Anti-site defects strongly affect thermoelectric properties in these alloys.