Electroluminescent devices

An electroluminescent device comprising:

• a first charge carrier injecting layer for injecting positive charge carriers;
• a second charge carrier injecting layer for injecting negative charge carriers;
• and
• a light-emissive layer located between the charge carrier injecting layers and comprising:
• a first component for accepting positive charge carriers from the first charge carrier injecting layer;
• a second component for accepting negative charge carriers from the second charge carrier injecting layer;
• and
• a third, organic light-emissive component for generating light as a result of combination of charge carriers from the first and second components;
• the first, second and third components being combined into a single molecule;
• and
• at least one of the first, second and third components forming a type II semiconductor interface with another of the first, second and third components.