ABSTRACT

This monograph deals with light emission at electrodes in electrochemical cells caused by energetic electron transfer (redox) reactions of electrogenerated species in solution. A typical system would involve a solution containing reactants A and D in a solution with supporting electrolyte, for example, MeCN with tetra-n-butylammonium perchlorate (TBAP), in an electrochemical cell with a platinum working electrode. The reaction sequence to generate an excited state and light emission is:

A + e− → A− • (reduction at electrode) (1) D − e− → D+ • (oxidation at electrode) (2) A− • + D+ •→ 1A* + D (excited state formation) (3) 1A* →A + hν (light emission) (4)

where A and D could be the same species, e.g., an aromatic hydrocarbon such as rubrene. The term electrogenerated chemiluminescence (ECL) was coined to describe this class of reaction [1,2] and to distinguish it from other systems where light is emitted from an electrode in electrochemical cells.