Considerable effort is currently expounded on the development and improvement of the myriad display technologies that have come to the market place. In this paper, several key questions are addressed in the development of the future generation of large-area field-emission-based displays based on semiconducting amorphous carbon thin films and carbon nanotubes (CNTs). The development of carbon-based cathodes has to date proceeded along empirical lines, with attempts to correlate the variation of field-emission characteristics with changes in deposition or post-deposition processing parameters, often without a full explanation being forthcoming. In addition, there have been incidents of incorrect interpretation of some of the results, due to a lack of appreciation of the significant differences between the different types of amorphous carbon film that exist. It is only recently that a fuller understanding of the different electron-emission mechanisms has begun to emerge through an understanding of the roles played by the electrical and structural inhomogeneity at nanometre level. This 'intrinsic dielectric inhomogeneity' is shown to possess some remarkable electronic properties, which also have important consequences for extrinsic inhomogeneous nanometre systems such as CNT and CNT-polymer-composite-based displays. The future outlook for broad-area displays based on amorphous carbon and CNTs is also addressed.