Aggregation induced emission of diketopyrrolopyrrole (DPP) derivatives for highly fluorescent red films.

A large number of diketopyrrolopyrrole (DPP) compounds showing aggregation induced emission (AIE) have been reported in the past few years. However, although DPP compounds exhibited AIE and excellent luminescence properties, their luminescence properties in solid or film states were not much focused on. Here we synthesized and characterized a series of DPP compounds with triphenylamine (TPA) moieties to investigate the AIE properties in the solid film state depending on the functional groups (TPA, BTPA, and MTPA) attached to the TPA moieties.

Simple modification of basic dyes with bulky &symmetric WCAs for improving their solubilities in organic solvents without color change.

A simple and easy solubility enhancement of basic dyes was performed with bulky and symmetric weakly coordinating anions (WCAs). The WCAs decreased the ionic character of the dyes by broadening the partial charge distribution and causing a screening effect on the ionic bonding. This new modification with WCAs has advantages in that it has no influence on the optical properties of the dyes.

Comparison between organic sensitizers containing stilbene and azo group as bridging unit for dye sensitized solar cells.

While azo dyes have been widely used in dye industry, the azo dyes have been seldom applied as sensitizers to dye sensitized solar cells. In this study, new metal-free organic sensitizers, ST and AZ, which are same structures except bridging units, were synthesized and evaluated. ST containing stilbene as bridging unit gave higher energy conversion efficiency than AZ containing azo group as bridging unit.

Influence of solvent and bridge structure in alkylthio-substituted triphenylamine dyes on the photovoltaic properties of dye-sensitized solar cells.

Three new triphenylamine dyes that contain alkylthio-substituted thiophenes with a low bandgap as a π-conjugated bridge unit were designed and synthesized for organic dye-sensitized solar cells (DSSCs). The effects of the structural differences in terms of the position, number, and shape of the alkylthio substituents in the thiophene bridge on the photophysical properties of the dye and the photovoltaic performance of the DSSC were investigated. The introduction of an alkylthio substituent at the 3-position of thiophene led to a decrease in the degree of redshift and the value of the molar extinction coefficient of the charge-transfer band, and the substituent with a bridged structure led to a larger redshift than that of the open-chain structure.