Laser-engineered black rutile TiO2 photoanode for CdS/CdSe-sensitized quantum dot solar cells with a significant power conversion efficiency of 9.1 %

The research deals with fabrication of CdS/CdSe-sensitized quantum dot sensitized solar cells (QDSSCs) with laser-engineered black rutile TiO 2 nanoparticles (TiO 2 -NPs) as the photoanode material. Three QDSSC devices with pristine and two types of black rutile TiO 2 -NPs engineered respectively in water and ethanol by intense femtosecond laser propagating in the filamentation regime were prepared in the same architecture. Extremely different power conversion efficiencies (PCE) of 1.43 %, 3.68 % and 9.11 %, in which the black TiO 2 -NPs-based devices show respectively a two-fold and six-fold PCE higher than the pristine TiO 2 -NPs, were obtained. The absorption and electrochemical impedance spectroscopy analyses revealed that the device with the highest PCE has the highest absorption efficiency in the wide spectral range from UV to mid-infrared and shunt resistance ( R sh ) of 1364.9 Ω, but the smallest series resistance ( R s ) of 190.3 Ω, which are attributed to the surface modification on the structural and optical properties of TiO 2 -NPs by femtosecond laser pulses.