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We developed a flexible active-matrix (AM) organic light-emitting diode (OLED) display driven by an organic thin-film transistor (TFT) (OTFT) using an air-stable organic semiconductor (OSC) of dinaphtho[2, 3 -b:2', 3' -f]thieno[ 3, 2 -b]-thiophene (DNTT) for the first time. We employed a low-temperature cross-linkable olefin-type polymer as the gate insulator (GI) and investigated the properties of the interface between DNTT and polymer GI. The top-contact TFT demonstrated a high mobility of up to 0.8 cm2/V·s and a near-zero turn-on voltage. DNTT has a deeper highest occupied molecular orbital level than other OSC materials, and this leads to large contact resistance between the source/drain (S/D) contact and OSC. Surface modifications to the S/D contact were investigated to enable efficient carrier injection to fabricate high-performance bottom-contact TFTs. The short-channel TFT we fabricated exhibited a high hole mobility of 0.5 cm2/V·s, a low subthreshold slope of 0.31, and excellent environmental and operational stability. The DNTT-based TFT also demonstrated good applications to processes with less deterioration. Finally, a 5-in flexible OLED display was successively fabricated by integrating the AM backplane with a phosphorescent OLED device. A high luminescence over 300 cd/ m2 was achieved by driving the DNTT-based OTFTs.