Improving the power factor (PF) of thermoelectric materials, crucial for enhancing the power output of thermoelectric generators, is challenging due to the adverse interdependence of the Seebeck coefficient and the electrical conductivity on carrier density. We introduce a novel strategy employing energy filtering via built-in potential barriers to alleviate this dependency, significantly enhancing the PF. Utilizing electron-beam lithography, we developed a Si-based nanodevice featuring a multiple well/barrier design. Measurements yielded a PF of 11 mW m⁻¹ K⁻², more than doubling the optimal PF achievable in bulk silicon. Experimental findings align well with theoretical models, affirming the efficacy of the approach. Leveraging established silicon technologies in device fabrication unveils pathways for on-chip micro-energy harvesters and localized Peltier coolers. Moreover, the results validate a material-agnostic energy filtering model, guiding the creation of PF-enhanced devices across various thermoelectric materials.