An orthogonal modulation enabled two-phase energy-efficient framework is presented for active cooperation between secondary users (SUs) and primary users (PUs) in a cognitive radio network. Since the PU has higher priority, and SUs compete for spectrum accessing, we model the power control problem as a Stackelberg game which incorporates throughput and energy consumptions into utility design. Due to the two-phase feature and SUs' power constraint, this game is played in an additive coupled sum constrained type. Unique Nash Equilibrium is achieved in analytical format, and simulations demonstrate the effectiveness of the proposed cooperation framework.