Impacts of electrogenerated chemiluminescence mechanism on the emission spectra and intensities.

Abstract

In this mini-review, recent progress in electrogenerated chemiluminescence (ECL) reported by our group is mainly introduced. First, the general principles of ECL and standard molecules for ECL are described, and then the ECL properties of thermally activated delayed fluorescence (TADF) molecules, pyrrolopyrrole aza-BODIPYs (PPABs), pyrene (Py) and its derivative, Eu(III) and Tb(III) complexes are introduced. The ECL efficiency of TADF molecules is increased by spin up-conversion from the T₁ to S₁ state, and that of PPABs is incremented kinetically due to the slower rate for the T₁ state formation than the S₁ state formation. The excimer formation mechanism of Py and its derivative in ECL is discussed. It is shown that very sharp ECL spectra can be obtained from Eu(III) and Tb(III) complexes. Furthermore, intense ECL for binary mixed systems using Ir(ppy)₃ and electron donor or acceptor molecules is described. These results provide insight into how the ECL mechanism affects emission intensity, efficiency, and spectrum.