Effect of quantum dot length on the degree of electron localization in polymer wires grown by molecular layer deposition

Abstract

Polymer multiple quantum dots were fabricated on glass substrates by molecular layer deposition. The quantum dot length was controlled by connecting three source molecules with monomolecular steps in designated sequences and was estimated from theoretical structures to be in the range 0.9–3.1 nm. With decreasing dot length, the absorption peak shifted to higher energy because of the quantum confinement effect; however, the photoluminescence peak shifted to lower energy due to a Stokes shift enhanced by increased π-electron localization. This suggests that π-electrons tend to be tightly confined in quantum dots with reduced lengths.