Unsymmetric platinum(ii) bis(aryleneethynylene) complexes as photosensitizers for dye-sensitized solar cells

Four new unsymmetric platinum(II) bis(aryleneethynylene) derivatives have been designed and synthesized, which showed good light-harvesting capabilities for application as photosensitizers in dye-sensitized solar cells (DSSCs). The absorption, electrochemical, time-dependent density functional theory (TD-DFT), impedance spectroscopic, and photovoltaic properties of these platinum(II)-based sensitizers have been fully characterized. The optical and TD-DFT studies show that the incorporation of a strongly electron-donating group significantly enhances the absorption abilities of the complexes. The maximum absorption wavelength of these four organometallic dyes can be tuned by various structural modifications of the triphenylamine and/or thiophene electron donor, improving the light absorption range up to 650nm. The photovoltaic performance of these dyes as photosensitizers in mesoporous TiO ₂ solar cells was investigated, and a power conversion efficiency as high as 1.57% was achieved, with an open-circuit voltage of 0.59 V, short-circuit current density of 3.63 mA cm ^-2, and fill factor of 0.73 under simulated AM 1.5G solar illumination.