A new organic TFF based current programmed pixel circuit for driving active-matrix OLEDs

A new current-driving pixel circuit for active-matrix organic light-emitting diodes (AMOLEDs), composed of four organic thin-film transistors (OTFTs) and one capacitor, is proposed using a current scaling method. Designing pixel circuits with OTFTs has many problems due to the instability of the OTFT parameters with the material characteristics still unknown. Despite the problems in using OTFTs to drive the pixel circuit, our work could be set as a goal for future OTFT development. The simulation results show enhanced reliability between the OTFT parameters with improved linearity between input data and OLED luminescence at low current levels. Also, large variation of OTFT parameters such as threshold voltage and mobility was successfully compensated to reliable values.