Effect of Surface Protonation on Device Performance and Dye Stability of Dye-sensitized TiO2 Solar Cell

A flat thin TiO₂ film was employed as the photo-electrode of a dye sensitized solar cell (DSSC), on which only a geometrical mono-layer of dye was attached. The effect of sur-face protonation by HCl chemical treatment on the performance of DSSCs was studied. The results showed that the short-circuit current Jsc increased significantly upon the HCl treatment, while the open-circuit voltage Voc decreased slightly. Compared to the untreated DSSC, the Jsc and energy conversion efficiency was increased by 31% and 25%, respectively, for the 1 mol/L HCl treated cell. TiO₂ surface protonation improved electronic coupling between the chemisorbed dye and the TiO₂ surface, resulting in an enhanced electron in-jection. The decreased open-circuit voltage after TiO₂ surface protonation was mainly due to the TiO₂ conduction band edge downshift and was partially caused by increased electron recombination with the electrolyte. In situ Raman degradation study showed that the dye stability was improved after the TiO₂ surface protonation. The increased dye stability was contributed by the increased electron injection and electron back reaction with the electrolyte under the open-circuit condition.     

氧化石墨烯在缺氧氧化锌薄膜表面的自发分裂

第一次从实验上展现了氧化石墨烯在缺氧氧化锌薄膜表面的自发分裂,即完整的氧化石墨烯片会自发分裂成许多小片. 此现象的可能机制是：氧化石墨烯表面存在链状的环氧基团,缺氧氧化锌薄膜表面的氧空位能够吸收氧化石墨烯表面的环氧基团,影响氧化石墨烯表面的环氧基团链的稳定性,导致环氧基团链自发打开,从而使完整的氧化石墨烯片破裂成很多小片.