A Top-Emitting Organic Light-Emitting Diode Employing a Top-Cathode Connected to Amorphous Silicon TFTs

An active-matrix organic light-emitting diode (AMOLED) display employing hydrogenated amorphous silicon thin-film transistor (TFT) prefers a cathode-contact structure rather than an anode-contact structure. In this paper, a normal top-emitting OLED (TOLED) employing cathode-contact structure has been proposed. The TOLED employing a thin Cr and a highly reflective AlNd alloy as an anode was fabricated. The current efficiency of AlNd alloy with 3 nm thick Cr as a hole-injection layer could be improved to a level of 6.3 cdA due to a highly reflective anode. In order to implement the normal TOLED structure, the cathode layer on top is separated as subpixels by negative photoresist separator. The AMOLED employing cathode-contact structure shows longer lifetime compared to that,employing anode-contact structure.