ABSTRACT
In organic LEDs, electricity is directly converted into light. Therefore, the evaluation of the overall light output and its relation to the driving current are of fundamental interest though understanding and tailoring of their emission color also falls in central device physics and practical application problems. A large amount of effort has been expended preparing various material compositions, particularly of the binary and ternary systems, and measuring their emission spectra with the hope of finding new and useful organic LED emitters. The following section provides an overview of various type of EL spectra and a good sampling of the empiricism which characterizes the work at many laboratories. However, the main subject of the present chapter is in correlating the optical properties of organic LEDs to their electrical characteristics.
