  Providing artificial light and enhancing the quality of the respective light
sources is of continued interest in the fields of solid state-, condensed
matter, and semiconductor physics. A lot of research has been done to increase
luminous efficiency, lifetime and colour stability of such devices. However,
the emission characteristics of a given light source don't necessarily comply
with today's, often sophisticated applications. Here, beam-shaping deals with
the transformation of a given light distribution into a customized one. This is
achieved by secondary optical elements often sporting elaborate designs, where
the actual light source takes up only a small fraction of the system's volume.
Such designs limit the final light source to one permanent operation mode,
which can only be overcome by employing mechanically-adjustable optical
elements. Here, we show that organic light-emitting diodes (OLEDs) make
real-time regulation of a beam-shape possible, without relying on secondary
optical elements and without using any mechanical adjustment. For a red
light-emitting two-unit OLED architecture, we demonstrate the ability of
continuous tuning between strongly forward and strongly sideward emission,
where the device efficiency is maintained at an application relevant level
ranging between 6-8% external quantum efficiency (EQE) for any setting chosen.
In combination with additional optical elements, customizable and tunable
systems are possible, whereby the tuning stems from the light source itself
rather than from the secondary optics.
