OLED devices with protection cover

#This invention relates to an OLED device with a protection cover made of a moldable material, a corresponding OLED system with at least one of these OLED devices and a method to manufacture such OLED devices and OLED systems.

#Organic light emitting devices (OLED devices) comprise a layer stack on top of a substrate with at least one light emitting layer arranged between two electrodes to apply a driving voltage to the light emitting layer(s). OLED devices typically comprise glass substrates and an encapsulation (a cover lid) for protection against environmental atmospheres, typically another glass plate. Glass plates have sharp edges, which could be a protection issue during handling and are fragile when exposed to mechanical loads, especially for large area OLED devices. Furthermore, the glass plates (substrate and/or cover lid) make it difficult to apply conventional fastening methods such as screwing, clamping, drilling etc. to mount the OLED devices to any desired location, e.g. on walls.

#It is an object of the present invention to provide an OLED device and a corresponding OLED system with improved mechanical loading capacity and reduced risk of injuries during handling of the OLED devices and OLED systems.

#FIG. 1: OLED device according to the present invention partly coated with the protection cover in a side view

#FIG. 2: OLED device according to the present invention fully covered with a transparent protection cover in a side view

#FIG. 3: OLED system according to the present invention fully covered with a transparent protection cover in (a) side view and (b) front view

#FIG. 1 shows an example of an OLED device 1 according to the present invention comprising a light emitting layer stack 3 arranged on top of a flat glass substrate 2. The light emitting layer stack 3 is encapsulated against the environmental atmosphere with a flat encapsulating glass cover 4, which is sealed to the substrate 2 with gastight glass frit 6. Substrate 2 and encapsulating cover 4 may have different shapes in other embodiments, also the material of the substrate and the encapsulating cover might be different. However, substrate 2 and encapsulating cover 4 have sharp edges causing a risk of injuries during handling and a risk of damages due to the fragile glass used from substrate and encapsulating cover. OLED devices are scalable and especially large area OLED light sources are desired to illuminate rooms etc. For large area OLED devices, the risk of damages will increase with increasing size of OLED device. The example shown in FIG. 1 is a so-called bottom emitter emitting light 7 through the substrate 2. The edges of the substrate 2 and the encapsulating cover 4 are covered by the protection cover 5 applied via molding techniques. In this embodiment the light emitting surface 711 of the substrate 2 is not coated. The coverage of the emitting surface 711 must be avoided in case of non-transparent (opaque) protection covers 5. However, for the same shape of the protection cover 5, also transparent materials can be used. The protection cover 5 is molded over the bare OLED device by placing the finished bare OLED device into a form subsequently filled with moldable material to provide the protection cover, where the light emitting surface 711 is shielded from being coated with the molded material. The shielding is not shown here.

#FIG. 2 shows an alternative embodiment of an OLED device 1 according to the present invention, where a transparent protection cover 5 (e.g. silicone, polyurethane or PMMA as the moldable material) fully encloses the OLED structure. Due to the transparent protection cover 5, the OLED device could be manufactured as a so-called transparent OLED using a transparent substrate (e.g. glass), a transparent encapsulating cover (e.g. glass) as well as transparent substrate electrode and back electrodes (not shown in details here). Such a transparent OLED device 1 comprises two light emitting surfaces 711, where the light 71 is additionally emitted through the encapsulating cover 4.

#The shape of the protection covers 5 of the embodiments shown in FIGS. 1 and 2 provide an additional gas barrier to the OLED structure to improve the sealing quality, e.g. of the gastight glass frit 6.