Caches are crucial yet power-hungry components in present-day computing systems. With the Negative Capacitance Fin Field-Effect Transistor (NCFET) gaining significant attention due to its internal voltage amplification, allowing for better operation at lower voltages (stronger ON-current and reduced leakage current), the introduction of NCFET technology in caches can reduce power consumption without loss in performance. Apart from the benefits offered by the technology, we leverage the unique characteristics offered by NCFETs and propose a dynamic voltage scaling based criticality-aware performance and energy optimization policy (CAPE) for on-chip caches. We present the first work towards optimizing energy in NCFET-based caches with minimal impact on performance. Compared to operating at a nominal voltage of 0.7 V, CAPE shows improvement in Last-Level Cache (LLC) energy savings by up to 19.2%, while the baseline policies devised for traditional CMOS- (/FinFET-) based caches are ineffective in improving NCFET-based LLC energy savings. Compared to the considered baseline policies, our CAPE policy also demonstrates better LLC energy-delay product (EDP) and throughput savings.