Recently, new wide-band energy gap semiconductors can be grown by ALD, PLD, sputtering, or MOCVD. They have great potential for the fabrication and application to TFTs. Inorganic semiconductors have good stability against environmental degradation over their organic counterparts, whereas organic materials are usually flexible, transparent, and when solution-processed at low temperatures, are prone to degradation when exposed to heat, moisture, and oxygen. For this Special Issue, we invited researchers to submit papers discussing the development of new functional and smart materials, and inorganic as well as organic semiconductor materials, such as ZnO, InZnO, GaO, AlGaO, AnGaO, AlN/GaN, conducting polymers, molecular semiconductors, perovskite-based materials, carbon nanotubes, carbon nanotubes/polymer composites, and 2D materials (e.g., graphene, MoS2) and their potential applications in display drivers, radio frequency identification tags, e-paper, gas, chemical and biosensors, to name but a few.