A thin film transistor array panel includes a substrate, a plurality of first and second signal lines crossing each other on the substrate, source electrodes connected to the first signal lines, drain electrodes connected to the second signal lines, pixel electrodes connected to the drain electrodes, a first partition formed on the source and drain electrodes and having a first opening, wherein a lower width of the first opening is wider than an upper width of the first opening, an organic semiconductor formed in the first opening and at least overlapping the portions of the source electrode and the drain electrode, and a gate electrode connected to the second signal line and at least overlapping the portion of the organic semiconductor.