Thermophotovoltaics (TPV) convert heat to electricity via thermal radiation. Photons with energies below the bandgap of the photovoltaic (PV) diode, resulting from the broad spectrum of the Planck blackbody distribution, are generally the dominant source of loss in TPV systems. Fortunately, these energy losses can be eliminated by selective emitters that have near-blackbody emission above the PV bandgap and low emission below the PV bandgap.1 Several materials have been proposed for selective emission, including plasmonic metamaterials,2–4 refractory plasmonic structures,5 rare earth materials,6–8 and photonic crystals (PhCs).9–24 However, realistic selective emitters still have residual low energy emission near the bandgap that can considerably limit the conversion efficiency. Significant improvement can be achieved by the use of cold-side PhC filters, including plasma filters, quarter-wave stacks,25 and rugate filters.26 These filters essentially reflect the low-energy photons back to the selective emitter, in a process known as photon recycling.27–32 In order to achieve sufficient photon recycling, proximity between the emitter and filter is required.33 In the typical cold-side filter configurations, where the filter is attached to the PV diode as an entire receiver, this requirement can be quantified by the view factor from the emitter to the receiver, which is the probability that emitted photons reach the receiver. Certain strategies, such as micro-gap or nanoscale-gap TPV, in fact require extremely high view factors to achieve evanescent coupling.34–36 However, it is extremely difficult to achieve high view factors in experiments, since a constant gap must be maintained between two surfaces when the distance is orders of magnitude smaller than the lateral width of each surface. The angular tolerance is impractically low. Although ultranarrow (scanning electron microscope-like) tips can achieve such small gaps, the associated power produced is extremely small.