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[Display omitted] • Black rutile TiO 2 nanoparticles (NPs) is fabricated by fs laser filament processing. • CdS/CdSe quantum dot sensitized solar cells (QDSSCs) with black TiO 2 -NPs are assembled. • A power conversion efficiency of 9.1 % in QDSSCs is achieved. • The increase in PCE is ascribed to the formed amorphous shell on the surface of TiO 2 -NPs. 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. [ABSTRACT FROM AUTHOR]

Yttrium-doped ZnO nanorod arrays were applied to photoanodes of quantum dot-sensitized solar cells (QDSCs). The introduction of yttrium to ZnO nanostructures facilitates the growth of ZnO nanorods and increases the amount of QD deposition with a large surface area. Furthermore, lower electrical resistance and longer electron lifetime were achieved with yttrium-doping owing to fewer defects and trap sites on the surface of yttrium-doped ZnO nanorods. As a result, the conversion efficiency of 3.3% was achieved with the optimized concentration of yttrium. [ABSTRACT FROM AUTHOR]

Pursuit of an efficient strategy for quantum dot-sensitized photoanode has been a persistent objective for enhancing photovoltaic performances of quantum dot-sensitized solar cell (QDSC). We present here the fabrication of the indium sulfide (In 2 S 3 ) quantum dot-sensitized titanium dioxide (TiO 2 ) photoanode by combining successive ionic layer adsorption and reaction (SILAR) with solvothermal processes. The resultant QDSC consists of an In 2 S 3 sensitized TiO 2 photoanode, a liquid polysulfide electrolyte, and a Co 0.85 Se counter electrode. The optimized QDSC with photoanode prepared with the help of a SILAR method at 20 deposition cycles and solvothermal method yields a maximum power conversion efficiency of 1.39%. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new way of preparation of rGO-Cu 2 S counter electrode using electrochemical co-deposition. • Low cost, minimal time and simple procedure for the fabrication process. • Reduced R ct and R s values of rGO-Cu 2 S CE for QDSSCs application. • Cell efficiency significantly improved by enhancement of current density and fill factor. Reduced graphene oxide (rGO)-Cu 2 S as a counter electrode (CE) is synthesized by a novel electrochemical method for quantum-dot-sensitized solar cell (QDSSC) applications. One-step electrochemical co-reduction using cyclic voltammetry for various cycles (3, 5, and 7), followed by sulfurization, is employed to obtain rGO-Cu 2 S CEs on the surface of fluorine-doped tin oxide. Compared with Pt and Cu 2 S CEs, rGO-Cu 2 S CEs (5) display lower charge transfer resistance (R ct) and higher electrocatalytic activity. This is because the introduction of rGO along with Cu 2 S in the rGO-Cu 2 S surface enhances the surface area and charge transfer and improves the electrical contact between the CEs and substrate surface. An optimum power conversion efficiency (η) of 4.26% is recorded for rGO-Cu 2 S (5) in CdS/CdSe/ZnS QDSSCs using a polysulfide electrolyte. QDSSCs with rGO-Cu 2 S (5) showed the highest short-circuit current density (J sc) of 17.2 mA cm−2, open circuit voltage (V oc) of 0.57 V, and fill factor of 44%. The obtained results are superior to those for Cu 2 S (3.77%) and Pt (2.44%) CEs. Additionally, the preparation method of rGO-Cu 2 S CEs is more scientific, less time-consuming, economical, and easy. [ABSTRACT FROM AUTHOR]

• PbS nanoparticles were grown by SILAR technique on electrochemically synthesized Cu 2 S nanosheets. • FTO/Cu 2 S/PbS CE has the stepwise energy level configuration which enhances the fast charge transportation. • FTO/Cu 2 S/PbS CE has enhanced electrocatalytic activity as compared to the FTO/Cu 2 S CE. • FTO/Cu 2 S/PbS exhibited excellent electrochemical stability in polysulfide electrolyte. • QDSSC with the FTO/Cu 2 S/PbS (3 SILAR cycles) CE showed the highest efficiency. A new strategy has been successfully developed for highly efficient copper sulfide/lead sulfide (Cu 2 S/PbS) counter electrodes (CEs) for quantum-dot-sensitized solar cells (QDSSCs). PbS nanoparticles were grown by successive ionic layer adsorption and reaction (SILAR) technique for various cycles (from 1 to 4) on electrochemically deposited Cu 2 S nanosheets. All the Cu 2 S and Cu 2 S/PbS CEs showed petal-like morphology and nanosized PbS nanoparticles were deposited over the Cu 2 S nanosheets. All FTO/Cu 2 S/PbS CEs exhibited superior electrocatalytic activity than FTO/Pt and FTO/Cu 2 S CEs. In particular, QDSSCs with FTO/Cu 2 S/PbS CE (3 SILAR cycles) exhibited extremely high short-circuit current density (18.08 mA cm−2) and fill factor (53.55%), resulting in a significantly enhanced power conversion efficiency as high as 5.28%. This is because the FTO/Cu 2 S/PbS CE not only exhibits the cascaded, stepwise energy level configuration, which enhances the fast charge transportation, but also serves as a blocking layer to prevent electrons from returning from the electrolyte to the Cu 2 S. Furthermore, FTO/Cu 2 S/PbS exhibited excellent electrochemical stability unlike FTO/Cu 2 S, owing to the passivation of PbS. [ABSTRACT FROM AUTHOR]