Ziming Zhou

Efficient quantum dot-sensitized solar cell with tunable energy band CdSexS(1−x) quantum dots

Tunable energy band CdSexS(1−x) quantum dots (QD) are developed for QD-sensitized solar cells(QDSSCs) by the successive ionic layer adsorption and reaction (SILAR) technique. The results indicated that the energy band and the light absorption of CdSexS(1−x) QDs could be controlled by the ratio of the sulphur (S) and the selenium (Se). Compared with the conventional CdS/CdSe system, its absorption spectrum and monochromatic incident photon-to-electron conversion efficiency (IPCE) spectrum show higher light harvest ability and a broader response wavelength region. As a result, a high energy conversion efficiency of 2.27% was obtained with the CdSexS(1−x) QDSSCs under AM 1.5 illumination of 100 mW cm−2. After being further treated with CdSe QDs, the CdSexS(1−x)/CdSe QDSSC yielded an energy conversion efficiency of 3.17% due to the enhanced absorption and the reduced recombination. It can be expected that tunable energy band QDs controlled by the ratio of atoms can contribute to higher efficiency QDSSCs.

Mesoporous nitrogen-doped TiO2 sphere applied for quasi-solid-state dye-sensitized solar cell

A mesoscopic nitrogen-doped TiO2 sphere has been developed for a quasi-solid-state dye-sensitized solar cell [DSSC]. Compared with the undoped TiO2 sphere, the quasi-solid-state DSSC based on the nitrogen-doped TiO2 sphere shows more excellent photovoltaic performance. The photoelectrochemistry of electrodes based on nitrogen-doped and undoped TiO2 spheres was characterized with Mott-Schottky analysis, intensity modulated photocurrent spectroscopy, and electrochemical impedance spectroscopy, which indicated that both the quasi-Fermi level and the charge transport of the photoelectrode were improved after being doped with nitrogen. As a result, a photoelectric conversion efficiency of 6.01% was obtained for the quasi-solid-state DSSC.