Particular attention has been focused on n-channel thin-film transistors (OTFTs) during the last few years the potentially cost-effective circuitry-based applications in flexible electronics, such as flexible radio-frequency identity tags, smart labels, and simple displays, will benefit from this fast development. This article reviews recent progress in performance and molecular design of n-channel semiconductors in the past five years, and limitations and practicable solutions for n-channel OTFTs are dealt with from the viewpoint of OTFT constitution and geometry, molecular design, and thin-film growth conditions. Strategy methodology is especially highlighted with an aim to investigate basic issues in this field.