The requirements of low-energy excitation combined with practical constraints of commercial supply and other issues, mandate the use of readily available commercial CRT phosphors, such as ZnS and Y2O3-based P22, for first-generation field-emission flat-panel displays. The use of these phosphors at low (e.g., less than or equal to 2-4 kV) excitation energies places considerable problems with brightness, efficacy, spectral response, long-term reliability, screen manufacture and materials synthesis, surface conditioning and outgassing protection, and low-cost manufacturing. The tradeoffs imposed by using phosphors designed for optimum performance in the 15-30 kV range at the low voltages employed by field-emission displays are presented and discussed.