The Thermophotovoltaic Efficiency Ceiling with Spectral Bookkeeping: Detailed-Balance Limits for Blackbody and Selective Emitters from 1200 K to 2400 K

Detailed-balance (Shockley-Queisser-type) thermophotovoltaic efficiency ceilings recomputed by numerical integration over the Planck spectrum for emitter temperatures 1200-2400 K, with explicit spectral bookkeeping: blackbody emitter without recycling versus sub-bandgap photon recycling at 90%, 95% and 100% reflectivity (100% being the net-power equivalent of an ideal selective emitter). Optimal bandgaps, recycling gains, and a quantitative decomposition of recent experimental progress toward 40%+ efficiency (LaPotin et al. 2022; Tervo et al. 2022; Roy-Layinde et al. 2024) into emitter-temperature and spectral-management contributions. Computation script and full numerical output included.