Reported here is the first crystalline inorganic organic hybrid material combining In, Ge, and Cu. The trimetallic system undergoes a nanoscale separation into small In-Ge-S supertetrahedral T2 clusters and large In-Cu-S T5 clusters, which are further assembled into a T2-T5 mixed layer. This material reveals the long-range crystallographically ordered assembly from supertetrahedral clusters with 3 orders of difference, the largest size mismatch known so far for mixed-supertetrahedral-cluster materials. Theoretical simulations were performed to probe the contribution to the band structure by the different-sized semiconducting clusters.