Pronounced Light\nInsensitivity in Low-Voltage n‑Channel\nOrganic Field-Effect Transistors with Channel Layers of Dinitrobenzothiadiazole-Containing\nConjugated Polymer

A light insensitivity in organic field-effect transistors\n(OFETs)\nis crucial for use under ambient light conditions that can cause additional\ncurrent flow in devices leading to unexpected noises. Here, we report\nlow-voltage driving n-channel OFETs, featuring very low light sensitivity,\nwith a channel layer consisting of dinitrobenzothiadiazole-containing\nconjugated polymer, poly[{2,5-bis(2-octyldodecyl)-3,6-bis(thien-2-yl)-pyrrolo[3,4-<i>c</i>]pyrrole-1,4-diyl}-<i>co</i>-{2,2′-(5,6-dinitro-2,1,3-benzothiadiazole)-5,5′-diyl}]\n(PODTPPD-DNBT). The PODTPPD-DNBT polymer, synthesized via the Stille\nreaction of two comonomers, showed an optical absorption up to 1100\nnm and a lowest unoccupied molecular orbital (LUMO) energy of 4.41\neV. The OFET devices with the PODTPPD-DNBT channels exhibited n-channel-mode\ntransistor behaviors at a low voltage (≤5 V) and very slightly\nincreased drain current under illumination with strong near-infrared\n(NIR, wavelength = 905 nm, intensity = 5.96 mW/cm<sup>2</sup>) and\nsimulated solar light (intensity = 100 mW/cm<sup>2</sup>). The PODTPPD-DNBT\nchannel layers delivered very low photoresponsivity of 6.95 mA/W under\nthe NIR light, which is less than 1% compared to the theoretical maximum\nvalue of 730 mA/W, and 2800% lower photoresponsivity (0.3 mA/W) compared\nto the same backbone polymer (PODTPPD-BT) without dinitro groups under\nthe simulated solar light.