Abstract: An electroluminescent device (13), such as a light emitting diode, which has a light-reflecting surface (10) causing undesirable reflection of ambient light incident on the device is provided with a combination of a reflective circular polarizer (17) and an absorbing circular polarizer (23) to suppress the undesirable reflection of ambient light thus improving the contrast of the device when used under high intensity ambient lighting conditions while maintaining a satisfactory brightness. The reflection band of the reflective circular polarizer regions (17?) of the reflective circular polarizer (17) are preferably tuned to the corresponding emission band of the luminescent regions (9?) of the electroluminescent device to further increase the contrast of the device while substantially maintaining the same brightness.

Abstract: This invention relates to a method of driving a dual-function light-emitting and light-sensing device (5) comprising an organic electroluminescent layer (1), such as a polymer layer or a small molecule compound layer, which is sandwiched between a first and a second electrode (2,3), comprising the following steps:—applying, during a emission state (t1), a first emission signal (V1, J1) to said electroluminescent layer (1), said first signal being such that light is generated by and emitted from said electroluminescent layer (1), and—applying, during a sensing state (t2), a second driving signal (V2,J2) to said organic electroluminescent layer (1), said second driving signal being such that the power of said second driving signal has essentially a zero value for accurately detecting an electric current generated in said organic electroluminescent layer when said organic electroluminescent layer is hit by external light This invention also relates to a dual-function light-emitting and light-sensing device and a