Photoluminescence study of light-induced modifications of (electro)chemically prepared polypyrrole

Permanent modification of polypyrrole (Ppy) after UV light irradiation were studied by photoluminiscence (PL), optical absorption and X-ray photoelectron spectroscopy (XPS). Ppy samples were prepared by electrochemical anodic oxidation and chemical oxidation. Influence of light exposure on polymer properties was studied under ambient condition, low pressure and after polymer annealing from 300K to 520K

The red and blue luminescence in silicon nanocrystals with an oxidized, nitrogen-containing shell

Traditionally, two classes of silicon nanocrystals (SiNCs) are recognized with respect to their light-emission properties. These are usually referred to as the “red” and the “blue” emitting SiNCs, based on the spectral region in which the larger part of their luminescence is concentrated. The origin of the “blue” luminescence is still disputed and is very probably different in different systems. One of the important contributions to the discussion about the origin of the “blue” luminescence was the finding that the exposure of SiNCs to even trace amounts of nitrogen in the presence of oxygen induces the “blue” emission, even in originally “red”-emitting SiNCs. Here, we obtained a different result. We show that the treatment of “red” emitting, already oxidized SiNCs in a water-based environment containing air-related radicals including nitrogen-containing species as well as oxygen, diminishes, rather than induces the “blue” luminescence