Abstract

Photovoltaic properties of nano-sized zinc oxide (ZnO) films sensitized with a conventional ruthenium complex (N719) and two metal-free organic indoline dyes (D-149 and D-205) were compared. The ZnO nanoparticles were deposited on transparent conductive aluminum-doped ZnO coated glass substrates (AZO) by spray-coating deposition method and then annealed in air at 500 °C. Using the ZnO-coated AZO as transparent conductive substrates, dye-sensitized solar cells (DSCs) were prepared with the N719, D149 and D205 dyes as the sensitizers. The photoaction spectra of the incident photon-to-current conversion efficiency (IPCE) of the DSCs revealed that the indoline-sensitized solar cells were higher and broader than the ruthenium-sensitized solar cell in the photo-absorption behavior. Under AM 1.5 simulated sunlight (1000 W m^-2), the indoline-sensitized ZnO solar cells yielded solar-to-electric energy conversion efficiency of 3.02 and 2.26% for the D-205 and D-149 respectively, while the N719 sensitized ZnO recorded only 0.97%. The superior performance of the indoline-sensitized solar cells was attributed to mainly higher sunlight harvesting efficiency of these metal-free organic dyes.

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