Tetrahydroquinoline dyes with different spacers for organic dye-sensitized solar cells

Novel organic dyes (C1-1, C1-5 and C2-1) with a tetrahydroquinoline moiety as the electron donor, different thiophene-containing electron spacers and a cyanoacrylic acid moiety as the electron acceptor have been designed and synthesized for the application in dye-sensitized solar cells (DSSCs). An interesting relationship between the dye structures, properties, and the performance of DSSCs based on these tetrahydroquinoline dyes is obtained. Although C2-1 dye, which has a rigid electron spacer, has the narrowest action spectrum among these dyes, it gives the highest solar-to-electricity conversion efficiency (η) of 4.49% (Voc = 600 mV, Jsc = 11.20 mA/cm2, ff = 0.67) of a DSSC under simulated AM 1.5 irradiation (100 mW/cm2). Under the same conditions, the η value of a DSSC based on N3 dye is 6.16%.