D-π-A Structured Porphyrin and Organic Dyes with Easily Synthesizable Donor Units for Low-Cost and Efficient Dye-Sensitized Solar Cells.

This study aimed to develop low-cost D-π-A structured porphyrin and organic dyes with easily synthesizable donor units instead of the conventional complex multistep synthetic donor unit of [bis(7-(2,4-bis(hexyloxy)phenyl)-9,9-dimethyl-9H-fluoren-2-yl)amine] used in and as well-known record cosensitizers with an extremely high power conversion efficiency (PCE). The design strategy concerned the easier synthesis of low-cost donor units with inversion structures in donor groups via donor structural engineering, particularly by changing the position of the fluorene and phenylene units in the donor moiety while keeping the π-bridge and acceptor unit unchanged, leading to the synthesis of two D-π-A structured porphyrins [ and ] and one D-π-A structured organic sensitizer [] for dye-sensitized solar cells (DSSCs). Specifically, porphyrin incorporated two hexyl chains into the 9-position of each fluorene, while and substituted two hexyloxy chain units to the terminal position of each fluorene in the donor groups of porphyrin dyes. The effect of the position of the fluorene and phenylene units in the donor moiety on the photochemical and electrochemical properties, as well as the photovoltaic performance, was compared with the reference dyes of and , previously reported by the research group. After optimizing the DSSC devices, and achieved a high PCE of 11.6 and 10.5%, respectively, while exhibited a little lower PCE of 10.3% under the standard AM 1.5G light intensity. The cell performance of DSSC devices based on and was inferior to the corresponding reference dyes of and due to their lower donating ability of than .