The first thermally conductive layer 80 may be integrally formed without an additional pattern for effective heat dissipation. For example, heat dissipation efficiency increases as the area of the first thermally conductive layer 80 increases. Accordingly the first thermally conductive layer 80 may be integrally formed as shown in the plan view of FIG. 1.

In a modified embodiment, at least a part of the first thermally conductive layer 80 including the end surface 80E of FIG. 7 may be formed to have a pattern 80P. As described with reference to FIG. 3, the upper substrate 300, the seal 400, the lower substrate 100, and the first thermally conductive layer 80 on the lower substrate 100 may be simultaneously cut along the cutting line CL. In this case, cutting the first thermally conductive layer 80 including a metal may be more difficult than cutting other structures, and metal fragments in the cutting process could be introduced into the panel in this cutting process.

Accordingly, a process of cutting the first thermally conductive layer 80 may be facilitated by patterning a portion of the first thermally conductive layer 80 corresponding to the cutting line CL and removing a part of the first thermally conductive layer 80.

A part of the first thermally conductive layer 80 is shown in FIG. 7 as having a slit shape including the pattern 80P In some implementations, the first thermally conductive layer 80 may have other suitable shapes.