An organic light emitting device composed of: a cathode; a layer including an organic electroluminescent material and a charge transport material; a layer including an electron accepting material; an anode capping layer; an anode; and a substrate in the sequence before the cathode or after the anode. First, a first frame is displayed on pixels at a first time. The cavity has a length, a first end, a second end, and a cavity wall with inner and outer surfaces. The locking assembly locks the position of the electrical contacts and restricts access to the actuating assembly. The evaporator unit comprises a liquid spraying device, preferably in the form of a piezoelectric spray nozzle.